Corvette C2 1963 1967 User Manual

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REPAIR & TUNE-UP GUIDE

CORVETTE 1963 to 1983

All U.S. and Canadian 305 « 327 • 350 • 396 * 427 • 454 models; including fuel injection

President, Chilton Enterprises David S. Loewith

Senior Vice President Ronald A. Hoxter

Publisher and Editor-in-Chief Kerry A. Freeman, S.A.E.

Managing Editors Peter M. Conti, Jr. a W. Calvin Settle, Jr., S.A.E.

Assistant Managing Editor Nick D'Andrea

Senior Editors Debra Gaffney a Ken Grabowski, A.S.E., S.A.E. Michael L.

Grady a Richard J. Rivele, S.A.E. Richard T. Smith n Jim Taylor Ron Webb

Director of Manufacturing Mike D'lmperio

Editor Tony Molla, S.A.E.

1BOOK

^COMPANY

ONE OF THE DIVERSIFIED PUBLISHING COMPANIES, A PART OF CAPITAL CITIES/ABC, INC.

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SAFETY NOTICE

Proper service and repair procedures are vital to the safe, reliable operation of all motor vehicles, as well as the personal safety of those performing repairs. This book outlines procedures for servicing and repairing vehicles using safe, effective methods. The procedures contain many NOTES, CAUTIONS and WARNINGS which should be followed along with standard safety procedures to eliminate the possibility of personal injury or improper service which could damage the vehicle or compromise its safety.

It is important to note that repair procedures and techniques, tools and parts for servicing motor vehicles, as well as the skill and experience of the individual performing the work vary widely. It is not possible to anticipate all of the conceivable ways or conditions under which vehicles may be serviced, or to provide cautions as to all of the possible hazards that may result. Standard and accepted safety precautions and equipment should be used when handling toxic or flammable fluids, and safety goggles or other protection should be used during cutting, grinding, chiseling, prying, or any other process that can cause material removal or projectiles.

Some procedures require the use of tools specially designed for a specific purpose. Before

substituting another tool or procedure, you must be completely satisfied that neither your personal safety, nor the performance of the vehicle will be endangered.

Although information in this guide is based on industry sources and is as complete as possible at the time of publication, the possibility exists that the manufacturer made later changes which could not be included here. While striving for total accuracy, Chilton Book Company cannot assume responsibility for any errors, changes, or omissions that may occur in the compilation of this data.

PART NUMBERS

Part numbers listed in this reference are not recommendations by Chilton for any product by brand name. They are references that can be used with interchange manuals and aftermarket supplier catalogs to locate each brand supplier's discrete part number.

SPECIAL TOOLS

Special tools are recommended by the vehicle manufacturer to perform their specific job. Use has been kept to a minimum, but where absolutely necessary they are referred to in the text by the part number of the tool manufacturer. These tools can be purchased, under the appropriate part number, through the Service Tool Division, Kent-Moore Corporation, 29784 Little Mack, Roseville, Ml 48066-

2298. In Canada, contact Kent-Moore of Canada, Ltd., 2395 Cawthra Mississauga, Ontario, Canada L5A 3P2. Before substituting any tool for the one recommended, read the SAFETY NOTICE at the top of this page.

ACKNOWLEDGMENTS

The Chilton Book Company expresses its appreciation to the Chevrolet Motor Division, General Motors Corporation for their generous assistance.

Information has been selected from Chevrolet shop manuals, owners manuals, service bulletins, and technical training manuals.

Published in Radnor, Pennsylvania 19089 by Chilton Book Company

Manufactured in the United States of America Tenth Printing, November 1994

Chilton's Repair & Tune-Up Guide: Corvette 1963-83

ISBN 0-8019-7681- 2 pbk.

Library of Congress Cataloging Card No. 85-47981

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CONTENTS

Troubleshooting

Emission Controls

and Fuel System

General Information

14 Routine Maintenance and Lubrication

Procedures 40 Tune-Up Specifications

and Maintenance

1 How to Use this Book

2 Tools and Equipment

Tune-Up and

Performance

Maintenance

39 Tune-Up

Drive Train

226

Driveshaft and U-Joints

227 Rear Axle

Suspension 242 Rear Suspension 253 Steering

Suspension and Steering

230 Front

Engine and Engine Rebuilding

61 Engine Electrical

System

88 Engine Service and Specifications

134 Emission Control System and Service 147 Fuel System Service

199 Lights, Fuses and Flashers

211 Manual Transmission 220 Automatic Transmission

Chassis Electrical

190 Accessory Service 195 Instruments Panel

Service

Clutch and Transmission

206 Clutch

Brakes

262 Brake System 269 Drum Brakes 271 Disc Brakes 274 Parking Brake

279 Problem Diagnosis

311 Mechanic's Data 312 Index

156Chilton's Fuel Economy

and Tune-Up Tips

284 Chilian's Body Repair

Tips

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Specifications Vehicle

Fill in this chart with the most commonly used specifications for your vehicle. Specifications can be found in Chapters 1 through 3 or on the tune-up decal under the hood of the vehicle.

Firing Order _______________________ '_______________________________ , _______________

Spark Plugs:

Type ----------------------------------------- ,---------------------------------------------------------: --------- '

Gap (in.)___________________________________________________________________ Point Gap (in.)__________________________________________________________________ Dwell Angle (°)_________________________________________________________________ Ignition Timing (°) ______________________________________________________________

Vacuum (Connected/Disconnected) ________________________________; __________ Valve Clearance (in.)

Intake ___________________

: ________

Exhaust.

Capacities

Engine Oil (qts)

With Filter Change__________ Without Filter Change_______

Cooling System (qts) ____________ Manual Transmission (pts)_

Type-----------------------_

Automatic Transmission (pts)_

Type-----------------------------

Front Differential (pts)_

Type ------------------

Rear Differential (pts)_

Type----------------_

Transfer Case (pts)_

Type---------------

FREQUENTLY REPLACED PARTS

Use these spaces to record the part numbers of frequently replaced parts.

PCV VALVE

Manufacturer ___________._ Manufacturer ______________ Manufacturer. Part No------------------------------Part No. _______________________ Part No.____

OIL FILTER

AIR FILTER

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General Information

and Maintenance

HOW TO USE THIS BOOK

Chilton's Repair & Tune-Up Guide for the Corvette is intended to help you learn more about the inner workings of your vehicle and save you money on its upkeep and operation.

The first two chapters will be the most used, since they contain maintenance and tune-up information and procedures. Studies have shown that a properly tuned and maintained car can get at least 10% better gas mileage than an out-of- tune car. The other chapters deal with the more complex systems of your car. Operating systems from engine through brakes are covered to the extent that the average do-it-yourselfer becomes mechanically involved. This book will not explain such things as rebuilding the differential for the simple reason that the expertise required and the investment in special tools make this task uneconomical. It will give you detailed instructions to help you change your own brake pads and shoes, replace points and plugs, and do many more jobs that will save you money, give you personal satisfaction, and help you avoid expensive problems.

A secondary purpose of this book is a reference for owners who want to understand their car and/or their mechanics better. In this case, no tools at all are required.

Before removing any bolts, read through the entire procedure. This will give you the overall view of what tools and supplies will be required. There is nothing more frustrating than having to walk to the bus stop on Monday morning because you were short one bolt on Sunday afternoon. So read ahead and plan ahead. Each operation should be approached logically and all procedures thoroughly understood before attempting any work.

All chapters contain adjustments, maintenance, removal and installation procedures, and repair or overhaul procedures. When repair is not considered practical, we tell you how to remove the part and then how to install the new or rebuilt replacement. In this way, you at least save the labor costs. Backyard repair of such components as the alternator is just not practical.

Two basic mechanic's rules should be mentioned here. One, whenever the left side of the car or engine is referred to, it is meant to specify die driver's side of ihe car. Conversely, the right side of the car means the passenger's side. Secondly, most screws and bolts are removed by turning counterclockwise, and tightened by turning clockwise.

Safety is always the most important rule. Constantly be aware of the dangers involved in working on an automobile and take the proper precautions. (See the section in this chapter "Servicing Your Vehicle Safely" and the SAFETY NOTICE on the acknowledgement page.)

Pay attention to the instructions provided. There are 3 common mistakes in mechanical work:

1. Incorrect order of assembly, disassembly or adjustment. When taking something apart or putting it together, doing things in the wrong order usually just costs you extra time; however, it CAN break something. Read the entire procedure before beginning disassembly. Do everything in the order in which the instructions say you should do it, even if you can't immediately see a reason for it. When you're taking apart something that is very intricate (for example, a carburetor), you might want to draw a picture of how it looks when assembled at one point in order to make sure you get everything back in its

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2 GENERAL INFORMATION AND MAINTENANCE

proper position. (We will supply exploded view whenever possible). When making adjustments, especially tune-up adjustments, do them in order; often, one adjustment affects another, and you cannot expect even satisfactory results unless each adjustment is made only when it cannot be changed by any other.

2. Overtorquing (or undertorquing). While it is more common for overtorquing to cause damage, undertorquing can cause a fastener to vibrate loose causing serious damage. Es pecially when dealing with aluminum parts, pay attention to torque specifications and uti lize a torque wrench in assembly. If a torque figure is not available, remember that if you are using the right tool to do the job, you will probably not have to strain yourself to get a fastener tight enough. The pitch of most threads is so slight that the tension you put on the wrench will be multiplied many, many times in actual force on what you are tight ening. A good example of how critical torque is can be seen in the case of spark plug instal lation, especially where you are putting the plug into an aluminum cylinder head. Too lit tle torque can fail to crush the gasket, causing leakage of combustion gases and consequent overheating of the plug and engine parts. Too much torque can damage the threads, or dis tort the plug, which changes the spark gap.

There are many commercial products available for ensuring that fasteners won't come loose, even if they are not torqued just right (a very common brand is "Loctite®"). If you're worried about getting something together tight enough to hold, but loose enough to avoid mechanical damage during assembly, one of these products might offer substantial insurance. Read the label on the package and make sure the product is compatible with the materials, fluids, etc. involved before choosing one.

3. Crossthreading. This occurs when a part such as a bolt is screwed into a nut or casting at the wrong angle and forced. Cross thread ing is more likely to occur if access is difficult. It helps to clean and lubricate fasteners, and to start threading with the part to be installed going straight in. Then, start the bolt, spark plug, etc. with your fingers. If you encounter resistance, unscrew the part and start over again at a different angle until it can be in serted and turned several turns without much effort. Keep in mind that many parts, espe cially spark plugs, use tapered thread s so that gentle turning will automatically bring the part you're threading to the proper angle if

you don't force it or resist a change in angle. Don't put a wrench on the part until it's been turned a couple of turns by hand. If you suddenly encounter resistance, and the part has not been seated fully, don't force it. Pull it back out and make sure it's clean and threading properly.

Always take your time and be patient; once you have some experience, working on your car will become an enjoyable hobby.

TOOLS AND EQUIPMENT

Naturally, without the proper tools and equipment it is impossible to properly service your vehicle. It would be impossible to catalog each tool that you would need to perform each or any operation in this book. It would also be unwise for the amateur to rush out and buy an expensive set of tools on the theory that he may need one or more of them at sometime.

The best approach is to proceed slowly, gathering together a good quality set of those tools that are used most frequently. Don't be misled by the low cost of bargain tools. It is far better to spend a little more for better quality. Forged wrenches, 10 or 12 point sockets and fine tooth ratchets are by far preferable to their less expensive counterparts. As any good mechanic can tell you, there are few worse experiences than trying to work on a car or truck with bad tools. Your monetary savings will be far outweighed by frustration and mangled knuckles.

Begin accumulating those tools that are used most frequently; those associated with routine maintenance and tune-up.

In addition to the normal assortment of screwdrivers and pliers you should have the following tools for routine maintenance jobs:

1. SAE (or Metric) or SAE/Metric wrenches—sockets and combination open end/box end wrenches in sizes from % in. (3 mm) to % in. (19 mm) and a spark plug socket (13/ie or % in. depending on plug type).

If possible, buy various length socket drive extensions. One break in this department is that the metric sockets available in the U. S. will all fit the ratchet handles and extensions you may already have (¥4, %, and Yi in. drive);

2. Jackstands—for support;

3. Oil filter wrench;

4. Oil filler spout—for pouring oil;

5. Grease gun—for chassis lubrication;

6. Hydrometer—for checking the battery;

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COMPRESSION GAUGE

WRENCH

DWELL TACHOMETER

BEAM-TYPE TORQUE WRENCH

GENERAL INFORMATION AND MAINTENANCE 3

FROM TOP: BATTERY TERMINAL TOOL; FEELER GAUGES; OIL SPOUT; FILTER

ALLEN WRENCHES

DWELL/TACHOMETER

VACUUM GAUGE

TIMING LIGHT

You need only a basic assortment of hand tools and test instruments for most maintenance and repair Jobs

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4 GENERAL INFORMATION AND MAINTENANCE

7. A container for draining oil;

8. Many rags for wiping up the inevitable

mess.

In addition to the above items there are several others that are not absolutely necessary, but handy to have around. These include oil dry, a transmission funnel and the usual supply of lubricants, antifreeze and fluids, although these can be purchased as needed. This is a basic list for routine maintenance, but only your personal needs and desire can accurately determine your list of tools. If you are serious about maintaining your own car, then a floor jack is as necessary as a spark plug socket. The greatly increased utility, strength, and safety of a hydraulic floor jack makes it pay for itself many times over through the years.

The second list of tools is for tune-ups. While the tools involved here are slightly more sophisticated, they need not be outrageously expensive. There are several inexpensive tach/dwell meters on the market that are every bit as good for the average mechanic as a $100.00 professional model. Just be sure that it goes to at least 1,200-1,500 rpm on the tach scale and that it works on 4, 6 or 8 cylinder engines. A basic list of tuneup equipment could include:

1. Tach-dwell meter.

2. Spark plug wrench.

3. Timing light (a DC light that works from the car's battery is best, although an AC light that plugs into 110V house current will suf fice at some sacrifice in brightness);

4. Wire spark plug gauge/adjusting tools.

5. Set of feeler blades.

Here again, be guided by your own needs. A feeler blade will set the points as easily as a dwell meter will read dwell, but slightly less accurately. And since you will need a tachometer anyway . . . well, make your own decision.

In addition to these basic tools, there are several other tools and gauges you may find useful. These include:

1. A compression gauge. The screw-in type is slower to use, but eliminates the possibility of a faulty reading due to escaping pressure.

2. A manifold vacuum gauge.

3. A test light, volt-ohm meter.

4. An induction meter. This is used for de termining whether or not there is current in a wire. These are handy for use if a wire is broken somewhere in a wiring harness.

As a final note, you will probably find a

torque wrench necessary for all but the most

basic work. The beam type models are perfectly adequate, although the newer click type are more precise.

Special Tools

Normally, the use of special factory tools is avoided for repair procedures, since these are not readily available for the do-it-yourself mechanic. When it is possible to perform the job with more commonly available tools, it will be pointed out, but occasionally, a special tool was designed to perform a specific function and should be used. Before substituting another tool, you should be convinced that neither your safety nor the performance of the vehicle will be compromised.

Some special tools are available commercially from major tool manufacturers. Others can be purchased from your car dealer. NOTE: Chevrolet special tools referred to in

this guide are available through the Service Tool Division, Kent-Moore Corporation, 29784 Little Mack, Roseville, Ml 48066-

2298. In Canada, contact Kent-Moore of Canada, Ltd., 2395 Cawthra Mississauga, Ontario, Canada L5A 3P2.

SERVICING YOUR VEHICLE SAFELY

It is virtually impossible to anticipate all of the hazards involved with automotive maintenance and service but care and common sense will prevent most accidents.

The rules of safety for mechanics range from "don't smoke around gasoline," to "use the proper tool for the job." The trick to avoiding injuries is to develop safe work habits and take every possible precaution.

Do's

• Do keep a fire extinguisher and first aid

kit within easy reach.

• Do wear safety glasses or goggles when cutting, drilling, grinding or prying, even if you have 20-20 vision. If you wear glasses for the sake of vision, then they should be made of hardened glass that can serve also as safety glasses, or wear safety goggles over your reg ular glasses.

• Do shield your eyes whenever you work around the battery. Batteries contain sul phuric acid; in case of contact with the eyes or skin, flush the area with water or a mixture

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GENERAL INFORMATION AND MAINTENANCE 5

of water and baking soda and get medical attention immediately.

• Do use safety stands for any undercar service. Jacks are for raising vehicles; safety stands are for making sure the vehicle stays raised until you want it to come down. Whenever the vehicle is raised, block the wheels remaining on the ground and set the parking brake.

• Do use adequate ventilation when work ing with any chemicals. Like carbon monox ide, the asbestos dust resulting from brake lining wear can be poisonous in sufficient quantities.

• Do disconnect the negative battery cable when working on the electrical system. The primary ignition system can contain up to 40,000 volts.

• Do follow manufacturer's directions whenever working with potentially hazard ous materials. Both brake fluid and antifreeze are poisonous if taken internally.

• Do properly maintain your tools. Loose hammerheads, mushroomed punches and chisels, frayed or poorly grounded electrical cords, excessively worn screwdrivers, spread wrenches (open end), cracked sockets, slip ping ratchets, or faulty droplight sockets can cause accidents.

• Do use the proper size and type of tool for the job being done.

• Do when possible, pull on a wrench han dle rather than push on it, and adjust your stance to prevent a fall.

• Do be sure that adjustable wrenches are tightly adjusted on the nut or bolt and pulled so that the face is on the side of the fixed jaw.

• Do select a wrench or socket that fits the nut or bolt. The wrench or socket should sit straight, not cocked.

• Do strike squarely with a hammer—avoid glancing blows.

• Do set the parking brake and block the drive wheels if the work requires that the en gine be running.

Dont's

• Don't run an engine in a garage or any where else without proper ventilation— EVER! Carbon monoxide is poisonous; it takes a long time to leave the human body and you can build up a deadly supply of it in your system by simply breathing in a little every day. You may not realize you are slowly poisoning yourself. Always use power vents, windows, fans or open the garage doors.

• Don't work around moving parts while wearing a necktie or other loose clothing. Short sleeves are much safer than long, loose sleeves and hard-toed shoes with neoprene soles protect your toes and give a better grip on slippery surfaces. Jewelry such as watches, fancy belt buckles, beads or body adornment or any kind is not safe working around a car. Long hair should be hidden under a hat or cap.

• Don't use pockets for toolboxes. A fall or bump can drive a screwdriver deep into your body. Even a wiping cloth hanging from the back pocket can wrap around a spinning shaft or fan.

• Don't smoke when working around gas oline, cleaning solvent or other flammable material.

• Don't smoke when working around the battery. When the battery is being charged, it gives off explosive hydrogen gas.

• Don't use gasoline to wash your hands; there are excellent soaps available. Gasoline may contain lead, and lead can enter the body through a cut, accummulating in the body until you are very ill. Gasoline also removes all the natural oils from the skin so that bone dry hands will suck up oil and grease.

• Don't service the air conditioning system unless you are equipped with the necessary tools and training. The refrigerant, R-12, is extremely cold and when exposed to the air, will instantly freeze any surface it comes in contact with, including your eyes. Although the refrigerant is normally non-toxic, R-12 becomes a deadly poisonous gas in the pres ence of an open flame. One good whiff of the vapors from burning refrigerant can be fatal.

HISTORY

The 1963 Corvette Stingray is a complete departure from the Corvettes which preceded it. The body, frame, and front and rear suspensions are all of new design. Engines and transmissions are the only components that were shared with the older models. Stingray body styling evolved from the original William Mitchell Stingray sports/racing car which competed in 1959-60. Fiberglass bodywork was retained, but included a steel, reinforcing framework around the passenger compartment. The convertible model, with or without hardtop, was retained and a new body style added, the fastback coupe. Retractable

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6 GENERAL INFORMATION AND MAINTENANCE

headlights, rotated by two electric motors, were also a new feature for the Corvette.

The frame is a ladder type with five crossmembers. The wheelbase has been reduced from the 102 in. of previous models to a more compact 98 in., and the rear track shortened by 2 in. This, coupled with component relocation, resulted in a 48/52 percent front/rear weight distribution; a marked improvement over the 53 percent front weight bias of earlier model Corvettes. Overall body height was reduced by 2 in. Front and rear suspensions are both independent and newly designed for the Stingray. The short/long arm front suspension has the upper arm tilted at an angle of 9° for an anti-dive effect under braking. Steering knuckles pivot in ball joints, instead of the king pins and bushings of the early Corvettes. The fully independent rear suspension is sprung with a nine-leaf transverse spring. Universal-jointed axle driveshafts transmit power to the wheels. Steering gear is recirculating ball type and the linkage includes a hydraulic damper. Power steering and brakes both became optionally available for the first time on a Corvette. Brake drums were enlarged and the brakes were made selfadjusting. Air conditioning became optionally available in kte 1963.

1964 saw detail body changes: functional passenger-compartment exhaust vents and elimination of the split rear window on the coupe, removal of the non-functional vents on the hood, and new wheel covers. The Muncie four-speed transmission, introduced in mid-year 1963 to repkce the Borg-Warner T10, became the optional four-speed. The solid lifter engines received larger intake and exhaust valves, and horsepower increased from 340 to 365 and from 360 to 375 for the carburetted and fuel-injected engines respectively. Transsistorized, breakerless ignition became optionally available on high performance engines in 1964.

In 1965, the big change was the introduction of four-wheel disc brakes. Braking power and fade resistance were greatly increased over the drum brakes. A flat hood replaced the 1964 hood which had twin indentations and other body changes included restyled wheel covers and functional exhaust vents behind the front wheels. A new version of the 327 cubic inch engine was introduced, the 350 horsepower, hydraulic-cam option. In midyear, a 396 cubic inch 425 horsepower engine was made available in the Corvette. 396 Corvettes were distinguished by the domed hood

required for carburetor clearance. Cars equipped with the 396 received a larger front stabilizer bar and the addition of a rear stabilizer bar. Side-mounted exhausts with chambered mufflers joined the option list in

1965. The 250, 365, and 375 horsepower engines

were dropped in 1966. The 300 horsepower, 327 cubic inch engine became the standard power plant and the standard three-speed transmission was synchronized in all forward gears. The 396 was bored out to 427 cubic inches and offered in two versions, a 425 horsepower and a milder 390 horsepower model. A heavy-duty, four-speed transmission was introduced for use with the high performance 427. Body changes included a new, egg-crate grille, restyled wheel covers, and the addition of backup lights.

1967 body styling changes included a hood scoop on 427 Stingrays, more subdued exhaust vents on the front fenders, and a center back-up light. Wheels were widened % inch to 6 inches and were slotted. The full wheel covers of former models were discarded for trim rings and center caps. The handbrake was changed to the pull-up type, and relocated to the center console. The 300, 350, and 390 horsepower engines remained the same for 1967. A triple-two barrel carburetor setup was added to the 390 horsepower 427 engine which added an additional 10 horsepower. Also, the same carburetor arrangement was added to the former 425 horsepower engine along with large port aluminum cylinder heads and a matching large port intake manifold. The three-two barrel carburetion also added 10 horsepower to this engine.

For the 1968 Corvette, a completely redesigned body and interior were installed on a basically unchanged chassis. Many of the styling features of the new body had been previewed on the Mako Shark show car. Overall body width and height were reduced, while front and rear tread increased with the use of one inch wider wheels. The convertible model was retained and the fastback coupe was replaced with a hardtop model featuring removable roof panels and rear window. Headlights on 1968 and later cars are raised automatically, with vacuum power when the lights are switched on. Wide oval F70-15 tires repkced the 7.75-15 tires of previous years. The two-speed, Powerglide automatic transmission was superseded by the three-speed Turbo Hydra-Matte, a significant improvement for general driving and

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GENERAL INFORMATION AND MAINTENANCE 7

performance usage. Engines remained the same, except for the addition of the air-injection reactor pump to control exhaust emissions. Corvettes sold in California have been equipped with the A.I.R. system since 1966.

Body styling remained die same for 1969 except for the addition of a Stingray script above the engine exhaust vent. The doors were slightly reshaped, widening the cockpit by one inch at shoulder height. Wheel width was increased to 8 inches, which also increased front and rear tread. The anti-theft ignition, steering, and transmission lock were introduced in 1969, with the ignition switch mounted on the steering column. Side exhausts were offered for the first time on the new body in 1969. Headlight washers were now included in the standard equipment. The small block stroke was increased to give a displacement of 350 cubic inches; however, horsepower ratings remained the same. 427 engine options remained the same for 1969 with the exception of the redesigned L88 engine. The 2nd design L88 used a large-port aluminum intake manifold with a single 850 cfin Holley carburetor, aluminum large-port open chamber cylinder heads, special camshaft with solid lifters, and redesigned HD connecting rods with 7/ie rod bolts. Also, the rare ZL-1 427 engine was an option on models of this year. The ZL-1 had the same horsepower rating of the L88 (430 hp) and shared many internal components with the L88. The rarity of the ZL-1 engine comes with the fact that it used an aluminum cylinder block with cast iron cylinder liner sleeves.

A new grille, larger parabolic reflector turn signals, and wheel well flares were added to the Stingray body for 1970. Cast metal grilles were added over the engine compartment exhaust vents and the tailpipe exits were made retangular. The seats were redesigned, lowering them one inch for more headroom and making the headrests integral. The 427 stroke was increased for 1970 to give a displacement of 454 cubic inches. Triple, two-barrel carburetion was dropped from the big blocks in

1970. A 370 horsepower 350 cubic inch engine, the LT-1, was introduced to answer the need for a solid lifter, high rpm small block engine. The three-speed, manual transmission was discontinued in 1970, and the fourspeed transmission and Positraction rear axle were made standard equipment.

Horsepower was decreased in 1971 through an across-the-board compression reduction. The 350 horsepower, hydraulic-cam version

of the small block was deleted from the option list.

1972 saw very few changes made to the Corvette. Rated horsepower was again down, due mostly to a new rating system which uti lizes net instead of gross power outputs. The audio alarm antitheft system is not a standard item, and the fiber optic light monitors have been discontinued. Only three engines are offered for 1972, two 350 cubic inch engines and one 454 cubic inch engine. There were no body changes, except for the addition of four new colors.

1973 saw the Corvette receive a new front end with a resilient body color bumper. The cool air induction hood covers the windshield wipers, allowing the wiper door and mecha nism to be eliminated. New body mounts and extra soundproofing were also added for 1973. GR70-15 steel-belted radial tires are stan dard equipment. As far as the small-block en gines are concerned, the LT-1 engine was discontinued for this model year. The succes sor to the LT-1 engine was the L82 high per formance engine which used the same short block as the LT-1 but through the use of a hydraulic camshaft and a Quadrajet carbu retor, the engine was again down on power. The 454 Turbo-jet was also available with a rating of 275 horsepower.

1974 was a year of very little change for the Corvette. A resilient rear section was added similar to the front system introduced in 1973. Three engines continued to be available, ex cept in California where only the two 350s were available.

Changes to the 1975 Corvette include a catalytic reactor to reduce emissions, a fuel cell-type fuel tank, and the dropping of the 454 engine.

Only one Corvette body style was available

for 1976, the convertible was dropped. The Turbo Hydra-Matic 350 replaced the 400 on the base engine. A partial steel underbody replaced the traditional fiberglass, which both improved body strength and heat protection from the exhaust system.

1977 was a year of refinements and a

slight appearance change from the 1976 model.

The 1978 Corvette received its most extensive change since its introduction of the current series in 1968 with a new fastback roof line resulting in a new cockpit design and a larger cargo area. A larger 24 gallon fuel cell type fuel tank is used for greater fuel capacity. Increased horsepower and torque ratings

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8 GENERAL INFORMATION AND MAINTENANCE

are achieved for the special performance engine over the base engine as a result of improvements of the induction and exhaust systems. The base engine uses a Muncie 4-speed manual transmission while the special performance engine uses a Borg-Warner. Both engines use the same Turbo Hydra-Matic transmission.

1979 was a year of very little change with

slight refinements of performance and appearance.

In 1980, the Corvette weight reduction plan was initiated. The following components were lightened to reduce the weight of the Corvette: front and rear bumper systems, hood, door panels, windshield and door glass (reduced thickness), selected frame members, and exhaust system. Appearance changes for 1980 include an integral front air dam, deeply recessed front grilles with integral parking lamps, cornering lamps, integral rear spoiler and functional black louvers on the front fenders. Transmission changes include the use of a locking torque convertor with the automatic transmission, and new gear ratios for the 4-speed manual transmission. Engine availability remains unchanged except for California models. California powertrain availability is limited to the new (to the Corvette) 305 engine with an automatic transmission. Miscellaneous components relating to drive train weight loss include the use of an aluminum intake manifold on the L82 engine, stainless steel exhaust manifolds on the 305 California engine, and a new aluminum differential mounting for all models.

The 1981 Corvette has only slight improvements in appearance and convenience items compared to the previous year. Both 350 engines (L48 and L82) and the 305 have been discontinued for 1981. A new L81 3504 bbl. engine is the only engine available for

1981. The Corvette recorded an industry first this year through the introduction of an FRP (Fiberglass Reinforced Plastic) rear spring which replaces the previous mutli-leaf metal rear spring assembly.

In 1982, appearance and convenience item changes are again minimal. The 350 4-bbl. engine has been discontinued and a 350 engine with twin-throttle body fuel injection (TBI) was introduced. The twin TBI system, referred to as "Cross-fire Injection" by the Chevrolet marketing force, is said to improve both throttle response and fuel economy as compared to the previous 4-bbl. carburetion system. Also, a new 4-speed automatic overdrive transmission with a locking torque con-

vertor is the only transmission available in

1982.

There is no 1983 Corvette model, but the 1984 Corvette is the first completely new design in over fifteen years. A new uniframe design body structure incororates high technology components such as forged aluminum suspension arms and fiberglass transverse leaf springs. The much-improved performance and handling characteristics of the 1984 Corvette continues the tradition of the ultimate American sport car. The L83 350 V8 with Cross Fire Fuel Injection is the only available engine in the 1984 Corvette, but two transmissions are offered. The THM 700 R4 automatic is standard, with an 83 mm 4 speed manual with automatic overdrive optional. The power rack and pinion steering and Z-51 sus pension package combine to provide precision and predictability at all speeds, along with the highest lateral acceleration figure (.95G) ever recorded for a production model at the CM Proving Grounds.

Corvettes have proven themselves in all types of automotive competition, and the Stringray has continued to bear the Corvette standard in many forms of racing. A Stingray coupe won the first race entered in October 1962 at Riverside Raceway. Since then, Corvettes have continued their winning ways in road racing in the SCCA A and B-Production classes. Corvettes have also taken numerous trophies in drag racing, in both the stock and modified classes. Sebring, Daytona, and Le Mans have witnessed many Corvette entries; Corvettes have placed well overall and succeeded in winning the GT class several times at these endurance races. The aerodynamic Stingray has also been utilized several times in setting Grand Touring class records during the Bonneville Speed Weeks. Just recently, a stock-bodied 1968 Corvette roadster equipped with a twin-turbocharged 430 cid big-block engine broke the stock-bodied record at Bonneville with two 240+ mph runs. That racing improves the breed has certainly proved to be true in the case of the Corvette, with many race-proven pieces having become standard equipment or options on production Corvettes.

SERIAL NUMBER IDENTIFICATION

Vehicle

The 1963 through 1967 Corvette vehicle serial number, body style, body trim number,

Page 13

GENERAL INFORMATION AND MAINTENANCE 9

5645

and paint combination is located on the instrument panel reinforcing member directly under the glove compartment. The vehicle serial number plate is located on the top left of the instrument panel (1968—76) and on the inside left windshield pillar post (1977-82). The body, trim, and paint number plate is located on the upper left hand door hinge pillar (1968-78) and on the upper horizontal surface of the shroud (1979—84). The vehicle serial number identifies die body style, model year, assembly plant, engine usage (1976-84), and production number.

1963-67 vehicle serial number location

INTERPRETING THE SERIAL NUMBER

A typical vehicle serial number tag yields manufacturer's identity, vehicle type, model year, engine type, assembly plant and production unit number when broken down as shown in the following charts.

Engine

All Corvette engine identification numbers are stamped on a pad of the engine block which is located at the lower front edge of the right side cylinder head. The first letter designates the plant in which the engine was manufactured and the numbers which follow identify the production date. The two or three letter suffix identifies the engine type and related equipment. On 1972 and later models, if the engine in the vehicle is known to be original, the fifth digit (1972-80) and the eighth digit (1981-84) of the serial number may also identify the engine used in the vehicle.

Serial number location on the drivers side windshield pillar—1977-82 models

|VIEW|A| Typical engine serial number

location

Mir Identity

V.I.N. Chart 1963-71

Body

Style

Model

Year

assigned to all Chevro let built vehicles

Model identification

Last number of model year (1968)

F-Flint

Unit numbering will start at 100,001 at all plants

Manufacturer's identity number

Assy Plant"

Unit

No. 100025

Page 14

10 GENERAL INFORMATION AND MAINTENANCE

1G1

Restraint Basic

Mfr.

Identity

Manufacturers identity number assigned to all Chevrolet built passenger cars

A—Non-passive restraint with manual seat belts

Y—Corvette

"87—Two door hardtop coupe

Engine code : 6(1981), 8(1982-84)

Manufacturers use only

B—1981, C—1982, E—1984, etc.

S—St. Louis, 5—Bowling Green

9—Unit numbering varies depending upon model

System

Type

Car

Model

V.I.N. Chart 1972-80

Mfr Series Iden- Code Body Engine Model bly Num flty1 Letter2 Style3 Model4 Year5 Plant6 her

assigned to all Chevro let built vehicles

Model identification

"Engine code

Last number of model year (1974) 6F-

Flint

Unit numbering will start at 000001 or 100,001 depend-

ing on the model

Manufacturer's identity number

Engine Identification

1963-64 327

cubic inch engine

Manual transmission RC Manual transmission and high performance RD

Special high performance RE Manual transmission and fuel injection RF Powerglide SC Powerglide and high performance SD

cubic inch engine

Manual transmission and A/C RP Manual transmission, high performance, RQ

A/C

Manual transmission, special high perfor- RR

mance, A/C Manual transmission and transistor ignition RT Fuel injection and transistor ignition RX Manual transmission, transistor ignition, A/C RU Powerglide and A/C SK Powerglide, high performance, A/C SL

cubic inch engine

Manual transmission HE High performance HF Fuel injection HG Special high performance HH

A/C HI

High performance and A/C HJ

1964 327

1965 327

V.I.N. Chart 1981-84

100025

Engine Model

Body

Type"

400.001

Assem- Unit

Check Digit"

Model Year

Engine Identification (cont.)

cubic inch engine

Special high performance and A/C HK

Transistor ignition HL Transistor ignition and A/C HM Fuel injection and transistor ignition HN Powerglide HO Powerglide and high performance HP Powerglide and A/C HQ Powerglide, high performance, A/C HR Special high performance and hydraulic HT

lifters

Special high performance, hydraulic lifters, HU

A/C

Special high performance, hydraulic lifters, HV

transistor ignition

Special high performance, hydraulic lifters, HW

transistor ignition, A/C

396 cubic inch engine

Special high performance IF

cubic inch engine

Manual transmission HE A.I.R. HH A.I.R. and Powerglide HR Special high performance and A.I.R. HD

Powerglide HO Special high performance HT

Power steering, special high performance, HP

A.I.R.

Special high performance, A/C, A.I.R. KH

427 cubic Inch engine

Special high performance and hydraulic IK

lifters High performance IL A.I.R. IM Special high performance IP Powerglide IQ Powerglide and A.I.R. IR

cubic inch engine

Manual transmission HE

A.I.R. HH

1965 327

1966 327

1967 327

Assy.

Plant

Unit

Number

Page 15

GENERAL INFORMATION AND MAINTENANCE 11

CTL

CTM

CTN

CTO

CTP

CTQ

CTR

CRI

CJL

CGY

CPJ

CPX

CKW

CRS

Engine Identification (cont.)

1967 327 cubic

Inch engine

A.I.R. and Powerglide HR Special high performance and A.I.R. HD Powerglide HO Special high performance HT Power steering, special high performance, HP

A/C

Special high performance, A/C, A.I.R. KH

427 cubic Inch engine

4-speed or Powerglide IL Triple carburetion JC A.I.T., special high performance, triple JE

carburetion Heavy duty IT Aluminum heads ID A.I.R. IM A.I.R. and triple carburetion JF A.I.R. and aluminum heads JH Powerglide IQ Powerglide and triple carburetion JD A.I.R. and Powerglide IR A.I.R., triple carburetion, Powerglide JG A.I.R., special high performance, triple JA

carburetion

1968 327 cubic

inch engine

Manual transmission HE Turbo Hydra-Matic HO Power steering and A/C HP Special high performance HT

427 cubic inch engine

High performance IL High performance and triple carburetion IM High performance, triple carburetion, Turbo IO

Hydro-Malic

Turbo Hydra-Matic IQ

Special high performance and triple car- IR

buretion High performance IT Special high performance, triple carbure- ID

tion, aluminum heads

1969 350 cubic

inch engine

High performance HW High performance and A/C HX

Manual transmission HY Turbo Hydra-Matic HZ

427 cubic inch engine

High performance, Turbo Hydra-Matic LL High performance LM

Triple carburetion, high performance, Turbo LN

Hydra-Matic

Heavy duty (L88) LO

Aluminum heads LP Triple carburetion and high performance LQ Triple carburetion and special high perfor- LR

mance

Engine Identification (cont.)

427 cubic inch engine

Triple carburetion, special high performance, heavy duty clutch Heavy duty and Turbo Hydra-Matic Triple carburetion, special high performance, Turbo Hydra-Matic

1970 350 cubic

inch engine

Manual transmission Turbo Hydra-Matic High performance High performance and A/C/ High performance and transistor ignition High performance, transistor ignition, A/C Special high performance Special high performance and transistor ig-

nition

Special high performance, transistor ignition,

4-speed

High performance, 4-bbl carburetor, Turbo

Hydra-Matic

High performance, 4-bbl carburetor, transistor

ignition

454 cubic inch engine

High performance, 4-bbl carburetor, Turbo

Hydra-Matic High performance and 4-bbl Heavy duty with 4-bbl Heavy duty with 4-bbl and Turbo Hydra-Matic High performance, 4-bbl, transistor ignition

1971 350 cubic

inch engine

270 hp, 4-speed 270 hp, THM 330 hp, 4speed 330 hp, THM 330 hp, 4-speed (HD)

454 cubic inch engine

365 hp, THM 365 hp, 4-speed 425 hp, 4speed 425 hp, THM

1972 350 cubic

inch engine

200 hp with 4-speed 200 hp with 4-speed and NOX control

(Calif.) 200 hp with Turbo Hydra-Matic 200 hp with Turbo Hydra-Matic and NOX

control (Calif.) 255 hp with 4-speed 255 hp with Turbo Hydra-Matic 255 hp with 4-speed and A.I.R. 255 hp with Turbo Hydra-Matic and A.I.R.

CTU

CTV CZN

CGW CZU

CZL CZN

CRI

CGT CGZ CJK

CPH CPW

CDH CKX

CDJ CKY

CKZ CRT

Page 16

12 GENERAL INFORMATION AND MAINTENANCE

350 (L83)

CLR

CLS

CUT

CMS

ZAC

ZAA

ZAB

ZAD

ZBA

ZBB

ZCA

ZAM

ZAK

ZBD

ZBC

ZDA

ZDC

ZDD

ZDB

ZBA

ZBC

Engine Identification (cont.)

454 cubic Inch engine

270 hp with 4-speed CPH 270 hp with Turbo Hydra-Matic CPJ 270 hp CSR.C

inch engine

190 hp with 4-speed CKZ

190 hp with 4-speed (Calif.) CLB

190 hp with Turbo Hydra-Malic CLA

190 hp with Turbo Hydra-Matic (Calif.) CLC 250 hp with 4-speed CLR 250 hp with 4-speed (Calif.) CIS 250 hp with Turbo Hydra-Matic CLD 250 hp with Turbo Hydra-Malic (Calif.) CLH

454 cubic inch engine

275 hp with 4-speed CWM 275 hp with 4-speed (Calif.) CWT 275 hp with Turbo Hydra-Matic CWR 275 hp with Turbo Hydra-Matic (Calif.) CWS

cubic inch engine

195 hp with 4-speed CKZ 195 hp with 4-speed (Calif.) CLB 195 hp with Turbo Hydra -Matic CLA 195 hp with Turbo Hydra-Matic (Calif.) CLC

250 hp with 4-speed CLR 250 hp with 4-speed (Calif.) CLS 250 hp with Turbo Hydra-Matic CLD 250 hp with Turbo Hydra-Matic (Calif.) CLH

454 cubic inch engine

270 hp with 4-speed CWM 270 hp with 4-speed (Calif.) CWT 270 hp with Turbo Hydra-Matic CWR 270 hp with Turbo Hydra-Matic (Calif.) CWS

cubic inch engine

195 hp with 4-speed CRJ, CUA, CUB

195 hp with Turbo Hydra-Matic CRK 250 hp with 4-speed CRL, CUT, CUD 250 hp with Turbo Hydra-Matic CRM

cubic inch engine

180 hp, 210 hp

cubic inch engine

180 hp, 210 hp

inch engine

185 hp (Calif.) 185 hp (high altitude)

1973 350 cubic

1974 350

1975 350

1976 350

CLM, CLR, CLS, CKW, CKX, CLS, CHC, CHR, CKC

1977 350

CKZ, CLA, CLB, CLC, CHD, CKD, CLD, CLF

1978 350 cubic

Engine Identification (cont.)

inch engine

185 hp AT. (Fed.) 185hpM.T. 225 hp M.T. 225hpA.T.

195 hp (Calif.) 195 hp with 4-speed 195 hp with Turbo Hydra-Matic

195 hp (High altitude) 225 hp with 4-speed 225 hp with Turbo Hydra -Matic

305 engine Std. 350 eng. (L48) w/M.T. Std. 350 eng. (L48) W/A.T. Hi Pert. 350 eng. (L82) w/M.T. Hi pert. 350 eng. (L82) w/A.T.

Federal models w/M.T. Calif, models w/M.T. Federal models w/AT. Calif, models w/A.T.

Federal models Calif, models

1978 350 cubic

1979

1980

1981

1982

1984

CLM CMR

ZFC, ZFD, ZFF, ZFN, ZFM

Transmission

5.7L EFI

number is located on a boss above the filler

plug. The Borg-Warner T-16, 3-speed serial

number is located on a boss at the right rear

corner of the transmission extension.

FOUR-SPEED MANUAL

Serial numbers of 4-speed transmissions used in models prior to 1979 are located at one of the three following locations: left side cover flange; left side of the case to the rear of the cover; or the left side of the case below the side cover.

1979 and later transmission I.D. numbers

are located on a flange at the right side top of the case.

TURBO HYDRA-MATIC

1978 and prior THM 350 serial numbers are

located on the right side vertical face of the

transmission oil pan.

THREE-SPEED MANUAL

The Muncie 3-speed serial

Page 17

GENERAL INFORMATION AND MAINTENANCE 13

3.55 Positraction

3.08 Positraction

3.55 Positraction

4.11 Positraction

396 engine

3.36

Positraction with

3.36 Positraction

3.08 Positraction

427 engine

3.36

427 engine

4.1 1

427 engine

4.56

Positraction with

3.55 Positraction

4.11 Positraction

1979 and later 3-speed automatic transmissions are coded either on the right side of the case above the front of the oil pan or on the case above the left rear of the oil pan. The THM 400 and the THM 700-R4 4-speed automatic transmissions serial number is located on a tag attached to the transmission case above the right rear corner of the oil pan.

Muncie 4-speed serial number location

Typical automatic transmission stamped serial number location (1) and VIN number location (2)

Rear Axle

All Corvette Stingrays have the rear axle serial number located on the bottom surface of the carrier at the cover mounting flange. The two or three-letter prefix in the serial number identifies the rear-axle gear ratio.

Rear axle serial number

Rear Axle Ratio Identification

Year

1963-64

1965

1966

1967

Axle Ratio and Type

Prefix

CA CJ

CB CC

CD CE CF

CZ CX

AK AL

AM AN AO AP AQ AR

AS AT

AU AZ FA FB FC

AL AM AN AO AP AR

AS AT

AU AZ

FA FB FC

AK AL AM AN AO AP

AS AT

AU AZ

3.36 with 3-speed

3.08 Positraction

3.36 Positraction

3.70 Positraction

4.11 Positraction

4.56 Positraction

3.08 with 4-speed

3.70 with 4-speed

3.36

3.36 Positraction

3.70 Positraction

4.56 Positraction

3.08

3.70 with 4-speed 3.08 Positraction with

Positraction with 396 engine 3.55 Positraction with 396 engine 3.70 Positraction with 396 engine 4.11

396 engine 4.56 Positraction with 396 engine

3.36

3.08 Positraction

3.55 Positraction

3.70 Positraction

4.11 Positraction

3.70 with 4-speed 3.08 Positraction with

Positraction with

427 engine 3.55 Positraction with 427 engine 3.70 Positraction with

Positraction with

427 engine

3.36

3.08 Positraction

3.36 Positraction

3.70 Positraction

3.70 with 4-speed 3.08 Positraction with 427 engine 3.36 Positraction with 427 engine 3.55 Positraction with 427 engine

Page 18

14 GENERAL INFORMATION AND MAINTENANCE

427 engine

4.1 1 Positraction with

427

engine

4.36 Positraction with

1968

3.36"

3.08 'Positraction

3.36 Positraction

3.55 Positraction

3.70 Positraction

4.11 Positraction

3.70

3.08 Heavy duty Positraction

3.36

HeaVy duty Positraction

3.08 Posjtraction

1969

3.08 Positraction

3.36 Positraction

3.55 Positraction

3.70 Positraction

4.11 Positraction

3.70

3.08 Heav

y duty Positraction

3.36 Heavy duty Positraction

3.08 Heavy duty Positraction

2.73 Heavy duty Positraction

3.55 Heavy duty Positraction

3.70 Heavy duty Positraction

4.11 Heavy duty Positraction

3.08 Positraction

CAM

3.36 Positraction

3.55 Positraction

3.70 Positraction with

high performance 350

and close

ratio 4

speed

CAP

4.11 Positraction

3.08 Positraction

3.36 Positraction

CAV

3.08 Positraction

3.08 Positraction with

Turbo Hydra

Matic

CAY

2.73 Positraction

3.36 Positraction with

Turbo Hydra

Matic

CAZ

3.70 Positraction

4.11 Positrac

tion

CFC

4.56 Positraction

3.55 Positraction

3.70 Positraction

4.11 Positraction

4.56 Positraction

3.08 Positraction

Rear Axle Ratio Identification

Year

1970

CAK

1971

AK AL

AN AO

AS AT

AW AK

AL AM AN

AP AS AT AU

AW AY AZ

FB FC

CAL CAN,

CAO,

CAS

CAT CAU

CAW

CAX

CFA CFB

CLR

AB AD

AW AX.LR

Prefix

(cont.)

Axle Ratio and Type

3.70 Positraction with

427 engine

3.08 Heavy duty Positraction

3.36

4.56 Positraction

3.36

3.36 Positraction

Rear Axle Ratio Identification

(cont.)

Year Prefix

1972 -75

1976-77

1978

1979

1980 DANA 1981

1982 DANA 1984 DANA

AX, LR AC AB AA AW AV

OA LR, OD OB OC

OK OM OH OJ

OH OJ

OJ OK

Axle Ratio and Type

3.36 Positraction

4.11 Positraction

3.70 Positraction

3.55 Positraction

3.08 Positraction

2.73 Positraction

3.08 Positraction

3.36 Positraction

3.55 Positraction

3.70 Positraction

3.08 Positraction

3.36 Positraction

3.55 Positraction

3.70 Positraction

3.36 Positraction

3.55 Positraction

3.70 Positraction

3.07 Positraction

2.87 Positraction w/A.T.

2.72 Positraction w/M.T.

2.87 Positraction

3.07 Positraction

3.31 Positraction

ROUTINE MAINTENANCE Air Cleaner

The air cleaner consists of a metal housing for a replaceable paper filter or permanent polyurethane element and the necessary hoses connecting it to the crankcase ventilation system. The air cleaner cover is held by a wing nut on all models. If your Corvette is equipped with a paper element, the factory recommends it should be replaced once every 12,000 miles (1963-72), every 24,000 miles (1973-74), every 30,000 miles (1975-84). Inspection and replacement should come more often when the car is operated under dusty conditions. To check the effectiveness of your paper element, remove the air cleaner assembly and, if the idle speed increases noticeably, the element is restricting airflow and should be replaced. Some high-performance models or cars equipped with optional air cleaners use a polyurethane element that must be removed, cleaned, and reoiled at 12,000 mile or 12 month intervals. Remove the filter and clean it in kerosene. Do not use paint thinner or similar solvent and then squeeze it dry. Allow it to soak in SAE 30 oil

Page 19

GENERAL INFORMATION AND MAINTENANCE 15

Remove and discard the old filter

—

PCV VALVE

The PCV valve is located in the rocker arm cover

on later models

Unscrew the wing nut and remove the cover

1. Air cleaner assembly 7. Manifold vacuum hose

2. Gasket 8. Air filter element

3. Hose clamp 9. Hood seal

4. Heat stove adapter 10. Air cleaner cover

5. Heat stove 11. Knurl nuts

6. Heat stove tube

Air cleaner assembly—1984 TBI shown

Check the small crankcase breather

Using a clean rag or a paper towel, wipe out the inside of the air cleaner

and again squeeze it dry using a clean cloth to remove excess oil. Clean the inside of the air cleaner housing before reinstalling either type of filter.

Positive Crankcase Ventilation (PCV)

The PCV valve is screwed into the carburetor or located in the ventilation hose on 1963 models. 1964 and 1965 models are not equipped with a PCV valve, but use a metered orifice fitting instead. This is not replaced, as it is a permanent part of the system, but it should be cleaned with solvent as a part of regular maintenance. The PCV valve

AIR CLEANER

Page 20

16 GENERAL INFORMATION AND MAINTENANCE

BATTERY TOP

BATT

ERY TOP

BATTERY TOP

STARTED

is located in the hose or in the rocker cover on later models. Replace the PCV valve and if so equipped the PCV filter, located in the air cleaner, every 12,000 miles (1963-71), every 24,000 miles (1972-74), every 30,000 miles (1975-84).

Evaporative Emissions Control System

This system, standard since 1970, eliminates the release of unburned fuel vapors into the atmosphere. The only periodic maintenance required is an occasional check of the connecting lines of the system for kinks or other damage and deterioration. Lines should be replaced only with quality fuel line or special hose marked "evap." Every 12,000 miles or 12 months (1970-71), every 24,000 miles or 24 months (1972-74), every 30,000 miles or 24 months (1975-81), the filter in the bottom of the carbon canister which is located in the engine compartment should be removed and replaced. This service is not required on 1982 and later models.

Battery

The major cause of slow engine cranking or a "no-start" condition is battery terminals which are loose, dirty, or corroded. Every 3 months or so, disconnect the battery and clean the terminals of both the battery and the cables. Cleaning tools for this purpose are available at most any auto parts store. When you buy a cleaning tool, be sure to specify whether you have a top terminal or side terminal battery, as the type of tool differs depending upon the style of battery. After you clean the terminals and reconnect the battery, apply a corrosion inhibitor to the terminals. Stay away from using any substance which is not meant specifically for this purpose. Do not apply the corrosion inhibitor to the mating surfaces of the terminals unless specified by the chemical manufacturer.

Batteries themselves can be cleaned using a solution of baking soda and water. Surface coatings on battery cases can actually conduct electricity which will cause a slight voltage drain, so make sure the battery case is clean.

Unless you have a "maintenance-free" bat-

tery, check the electrolyte level in the battery (see Battery under Fluid Level Checks in this chapter). Be sure that the vent holes in the caps and the vent tubes are not blocked with grease or dirt. The vent system allows

DARKENED INDICATOR (WITH GREEN

DOT)

MAY BE JUMP

Maintenance-free batteries contain their own built-in hydrometer

DARKENED

INDICATOR (NO

GREEN DOT)

MAY BE JUMP

STARTED

hydrogen gas, formed by the chemical reac-

tion in the battery, to escape freely. If your

vehicle is equipped with a Delco Freedom®

or Freedom II® battery, check the color of

the battery condition indicator (which is ac-

tually a built-in hydrometer). If the indicator is green, the battery is sufficiently charged and in good condition. If the indicator is

darkened, the battery is discharged. In this

case, the reason for die discharge should be

determined (e.g.—low alternator output,

voltage draw, etc.) then the battery itself

should be tested and recharged. If the indi-

cator is light without a green dot visible or if

it is yellow in color, the battery must be replaced—DO NOT attempt to test or re-

charge a battery with this indicator condition. Test the electrical system after the battery has been replaced. CAUTION: On

later models with electronic engine

controls, the electrical system and control

unit can be quickly damaged by improper

connections, high-output battery chargers or

incorrect service procedures.

Check the battery cables for signs of wear or chafing. If corrosion is present on the cable or if the cable is visible through the cable jacket, the cable assembly should be replaced. If cable replacement is necessary, it is best to purchase a high-quality cable that has the cable jacket sealed to tite terminal ends. See "Jump Starting" for more informa tion.

REPLACEMENT BATTERIES

The cold power rating o of a battery measures battery starting performance and provides an approximate relationship between battery size and engine size. The cold power rating of a replacement battery should match or exceed your engine size in cubic inches. Replace the battery tray, if corroded excessively.

DO NOT JUMP

START

Page 21

GENERAL INFORMATION AND MAINTENANCE 17

A/C COMPRESSOR

A.I.R. PUMP

PUMP

WATER PUMP

Heat Riser

The heat riser is a thermostatically or vacuum operated valve in the exhaust manifold. Not all engines have one. It closes when the engine is warming up, to direct hot exhaust gases to the intake manifold, in order to preheat the incoming fuel/air mixture. If it sticks shut, the result will be frequent stalling during warmup, especially in cold and damp weather. If it sticks open, the result will be a rough idle after the engine is warm. There is only one heat riser on a V8. The heat riser should move freely. If it sticks, apply GM Manifold Heat Control Solvent or something similar (engine cool) to the ends of the shaft. Sometimes rapping the end of the shaft sharply with a hammer (engine hot) will break it loose. If this fails, components must be removed for further repairs. See "Exhaust Manifold" for removal procedures.

Drive Belts

CHECKING AND ADJUSTING TENSION

Check the drive belts every 6,000 miles for evidence of wear such as cracking, fraying, and incorrect tension. Determine the belt tension at a point halfway between the pulleys by pressing on the belt with moderate thumb pressure. The belt should deflect about V* inch at this point. If the deflection is found to be too much or too little, loosen the mounting bolts and make the adjustments.

On all 1984 and later engines, a single serpentine belt is used to drive all accessories formerly driven with V-belts. Belt tension is maintained by a spring loaded tensioner which has the ability to maintain belt tension over a broad range of belt lengths. There is an indicator to make sure the tensioner is adjusted to within its operating range. The belt tension is adjusted with a Vz inch breaker bar inserted into the square hole in the tensioner arm and a belt tension gauge (BT 7825 or equivalent) to 120—140 Ibs, as read on the

Measuring fan belt tension

LOCATING SLOT =. A/C COMPRESSOR ^ BRACKET

Serpentine drive belt tensioner—1984 and later

CRANKSHAFT

TENSIONER / GENERATOR

Serpentine drive belt installation

LOCATING TAB

OPERATING RANGE

„,-.„

TENSIONER

BRACKET

POWER STEERING i \

tension gauge installed between the alternator and the A.I.R. pump.

Cooling System

CAUTION: Do not perform any coolant

system services on a hot engine.

At least once every 2 years, the engine cooling system should be inspected, flushed, and refilled with fresh coolant. If the coolant is left in the system too long, it loses its ability to prevent rust and corrosion. If the coolant has too much water, it won't protect against freezing.

The pressure cap should be looked at for signs of age or deterioration. Fan belt and other drive belts should be inspected and adjusted to the proper tension. (See checking belt tension).

Hose clamps should be tightened, and soft

or cracked hoses replaced. Damp spots, or accumulations of rust or dye near hoses, water

Page 22

18 GENERAL INFORMATION AND MAINTENANCE

HOW TO SPOT WORN V-BELTS

V-Belts are vital to efficient engine operation—they drive the fan, water pump and other accessories. They require little maintenance (occasional tightening) but they will not last forever. Slipping or failure of the V-belt will lead to overheating. If your V-belt looks like any of these, it should be replaced.

This belt has deep cracks, which cause it to flex. Too much flexing leads to heat build-up and premature failure. These cracks can be caused by using the belt on a pulley that is too small. Notched belts are available for small diameter pulleys.

Cracking or weathering

Oil and grease on a belt can cause the belt's rubber compounds to soften and separate from the reinforcing cords that hold the belt together. The belt will first slip, then finally fail altogether.

Softening (grease and oil)

Glazing

Worn cover

Glazing is caused by a belt that is slipping. A slipping belt can cause a run-down battery, erratic power steering, overheating or poor accessory performance. The more the belt slips, the more glazing will be built up on the surface of the belt. The more the belt is glazed, die more it will slip. If the glazing is light, tighten the belt.

The cover of this belt is worn off and is peeling away. The reinforcing cords will begin to wear and the belt will shortly break. When the belt cover wears in spots or has a rough jagged appearance, check the pulley grooves for roughness.

This belt is on the verge of breaking and leaving you stranded. The layers of the belt are separating and the reinforcing cords are exposed. It's just a matter of time before it breaks completely.

Separation

Page 23

GENERAL INFORMATION AND MAINTENANCE 19

HOW TO SPOT BAD HOSES

Both the upper and lower radiator hoses are called upon to perform difficult jobs in an inhospitable environment. They are subject to nearly 18 psi at under hood temperatures often over 280°F., and must circulate nearly 7500 gallons of coolant an hour—3 good reasons to have good hoses.

A good test for any hose is to feel it for soft or spongy spots. Frequently these will appear as swollen areas of the hose. The most likely cause is oil soaking. This hose could burst at any time, when hot or under pressure.

Swollen hose

Cracked hoses can usually be seen but feel the hoses to be sure they have not hardened; a prime cause of cracking. This hose has cracked down to the reinforcing cords and could split at any of the cracks.

Cracked hose

Frayed hose end (due to weak clamp)

Weakened clamps frequently are the cause of hose and cooling system failure. The connection between the pipe and hose has deteriorated enough to allow coolant to escape when the engine is hot.

Debris, rust and scale in the cooling system can cause the inside of a hose to weaken. This can usually be felt on the outside of the hose as soft or thinner areas.

Debris In cooling system

Page 24

20 GENERAL INFORMATION AND MAINTENANCE

heck the radiator cap's rubber gasket and metal

pump or other areas, indicate possible leakage, which must be corrected before filling die system with fresh coolant.

CHECK THE RADIATOR CAP

While you are checking me coolant level, also check the condition of the radiator cap gasket and the seal inside of the cap (if your vehicle uses a coolant recovery system). The radiator cap is designed to seal the cooling system under normal operating conditions which allows the system to build-up a certain amount of pressure (this pressure rating is stamped or printed on the cap). The pressure in the system raises the boiling point of the coolant to help prevent overheating. If the radiator cap does not seal, the boiling point of the coolant is lowered and overheating will occur. If the cap must be replaced, purchase the new cap according to the type of system you have (with or without a coolant recovery tank) and the pressure rating which is specified for your vehicle.

CLEAN RADIATOR OF DEBRIS

Periodically clean any debris—leaves, paper, insects, etc.—from the radiator fins. Pick the large pieces off by hand. The smaller pieces can be washed away with water pressure from a hose.

Carefully straighten any bent radiator fins with a pair of needle nose pliers. Be careful— the fins are very soft. Don't wiggle the fins back and forth too much. Straighten them once and try not to move them again.

DRAIN AND REFILL THE COOLING SYSTEM

Completely draining and refilling the cooling system every two years at least will remove accumulated rust, scale and other deposits. Coolant in late model cars is a 50-50 mixture of ethylene glycol and water for year round

SEAL

seal for deterioration at least once a year

GASKET

use. Use a good quality antifreeze with water pump lubricants, rust inhibitors and other corrosion inhibitors along with acid neutralizers.

1. Drain the existing antifreeze and cool ant. Open the radiator and engine drain petcocks, or disconnect die bottom radiator hose, at the radiator outlet.

NOTE: Before opening the radiator pet-

cock, spray it with some penetrating lubricant.

2. Close the petcock or re-connect the lower hose and fill the system with water.

3. Add a can of quality radiator flush.

4. Idle the engine until the upper radia tor hose gets hot.

5. Drain the system again.

6. Repeat this process until the drained water is clear and free of scale.

7. Close all petcocks and connect all the hoses.

8. If equipped widi a coolant recovery system, flush die reservoir witii water and leave empty.

9. Determine die capacity of your cool ing system (see capacities specifications). Add a 50/50 mix of quality antifreeze (ethylene glycol) and water to provide die desired pro tection.

10. Run die engine to operating tempera

ture.

11. Stop die engine and check die coolant

level.

12. Check die level of protection with an anti-freeze tester, replace die cap and check for leaks.

Air Conditioning

SAFETY PRECAUTIONS

There are two particular hazards associated widi air conditioning systems and diey bodi relate to die refrigerant gas.

First, die refrigerant gas is an extremely cold substance. When exposed to air, it will instantly freeze any surface it comes in contact widi, including your eyes. The odier hazard relates to fire. Ahhough normally nontoxic, refrigerant gas becomes highly poisonous in die presence of an open flame. Inhalation of die vapor formed by burning refrigerant can be fetal. Keep all forms of fire (including cigarettes) well clear of die airconditioning system.

Any repair work to an air conditioning system should be left to a professional. Do not, under any circumstances, attempt to loosen

Page 25

GENERAL INFORMATION AND MAINTENANCE 21

or tighten any fittings or perform any work other than that outlined here.

CHECKING FOR OIL LEAKS

Refrigerant leaks show up as oily areas on the various components because the compressor oil is transported around the entire system along with the refrigerant. Look for oily spots on all the hoses and lines, and especially on the hose and tubing connections. If there are oily deposits, the system may have a leak, and you should have it checked by a qualified repairman.

NOTE: A small area of oil on the front of

the compressor is normal and no cause for alarm.

CHECK THE COMPRESSOR BELT

Refer to the section in this chapter on "Drive Belts."

KEEP THE CONDENSER CLEAR

Periodically inspect the front of the condenser for bent fins or foreign material (dirt, buts, leaves, etc.) If any cooling fins are bent, straighten them carefully with needlenosed pliers. You can remove any debris with a stiff bristle brush or hose.

OPERATE THE AIC SYSTEM PERIODICALLY

A lot of A/C problems can be avoided by simply running the air conditioner at least once a week, regardless of the season. Simply let the system run for at least 5 minutes a week (even in the winter), and you'll keep the internal parts lubricated as well as preventing the hoses from hardening.

REFRIGERANT LEVEL CHECK

There are two ways to check refrigerant level, depending on how your model is equipped.

With Sight Glass

The first order of business when checking the sight glass is to find the sight glass. It will either be in the head of the receiver/drier, or in one of the metal lines leading from the top of the receiver/drier. Once you've found it, wipe it clean and proceed as follows:

1. With the engine and the air conditioning system running, look for the flow of refrigerant through the sight glass. If the air conditioner is working properly, you'll be able to see a continuous flow of clear refrigerant through the sight glass, with perhaps an occasional bubble at very high temperatures.

Air conditioning sight glass

2. Cycle the air conditioner on and off to make sure what you are seeing is clear refrig erant. Since the refrigerant is clear, it is pos sible to mistake a completely discharged sys tem for one that is fully charged. Turn the system off and watch the sight glass. If there is refrigerant in the system, you'll see bub bles during the off cycle. If you observe no bubbles when the system is running, and the air flow from the unit in the car is delivering cold air, everything is OK.

3. If you observe bubbles in the sight glass while the system is operating, the system is low on refrigerant. Have it checked by a professional.

4. Oil streaks in the sight glass are an in dication of trouble. Most of the time, if you see oil in the sight glass, it will appear as a series of streaks, although occasionally it may be a solid stream of oil. In either case, it means that part of the charge has been lost.

Without Sight Glass

On vehicles that are not equipped with sight glasses, it is necessary to feel the temperature difference in the inlet and outlet lines at the receiver/drier to gauge the refrigerant level. Use the following procedure:

1. Locate the receiver/drier. It will gen erally be up front near the condenser. It is shaped like a small fire extinguisher and will always have two lines connected to it. One line goes to the expansion valve and the other goes to the condenser.

2. With the engine and the air conditioner running, hold a line in each hand and gauge their relative temperatures. If they are both the same approximate temperature, the sys tem is correctly charged.

3. If the line from the expansion valve to the receiver/drier is a lot colder than the line from the receiver/drier to the condenser, then the system is overcharged. It should be noted that this is an extremely rare condition.

Page 26

22 GENERAL INFORMATION AND MAINTENANCE

4. If the line that leads from the re ceiver/drier to the condenser is a lot colder than the other line, the system is under charged.

5. If the system is undercharged or over charged, have it checked by a professional air conditioning mechanic.

Windshield Wipers

Intense heat from the sun, snow and ice, road oils and the chemicals used in windshield washer solvents combine to deteriorate the rubber wiper refills. The refills should be replaced about twice a year or whenever the blades begin to streak or chatter.

WIPER REFILL REPLACEMENT

Normally, if the wipers are not cleaning the windshield properly, only the refill has to be replaced. The blade and arm usually require replacement only in the event of damage. It is not necessary (except on new Tridon refills) to remove the arm or the blade to replace the refill (rubber part), though you may have to position the arm higher on the glass. You can do this turning the ignition switch on and operating the wipers. When they are positioned where they are accessible, turn the ignition switch off.

There are several types of refills available and your vehicle could have any kind, since aftermarket blades do not necessarily use the same refill as original equipment blades. The two most popular original equipment types are what we refer to .as the first and the third types. The remaining styles are used mainly as aftermarket replacements.

The first type of blade uses a release button that is pushed down to allow the refill to slide out of the yoke jaws. The new refill slides in and locks in place.

The second type of refill is removed by lo-

cating where the metal backing strip (or where the refill) is wider and inserting a small screwdriver between the frame and the metal backing strip. Press down to release the refill from the retaining tab.

The third type of refill is replaced by

squeezing the two metal tabs located at the end of the refill and sliding the refill out of the frame jaws. When the new refill is installed, the tabs will click into place and lock the refill.

The fourth type of refill is termed the "polycarbonate type." The refill of this type is held into place by a locking lever which is pushed

downward out of the groove in the arm to free the refill. The new refill will lock into place automatically as it is installed.

The fifth type of refill is used with the Tridon blade. The Tridon refill has a plastic backing strip with a notch about an inch from the end. Hold the blade (frame) on a hard surface so that it is tightly bowed. Grip the tip of the backing strip and pull upward while twisting counterclockwise. The backing strip will snap out of the retaining tab. Do this for the remaining tabs until the refill is free of the arm. The refills must be replaced with identical new refills.

No matter what type of refill is used, be sure that all of the frame claws engage the refill. Before operating the wipers, be sure that no part of the metal frame contacts the windshield glass.

Fluid Level Checks

ENGINE OIL

The engine oil level is checked with the dipstick, which is located either on the left side of the engine (small-blocks) or the right side of the engine (big-blocks).

NOTE: The oil should be checked before

the engine is started or five minutes after

the engine has been shut off. This gives the

oil time to drain back to the oil pan and

prevents an inaccurate oil level reading.

Remove the dipstick from its tube, wipe it

clean, and insert it back into the tube. Remove it again and observe the oil level. It should be maintained between the "full" and "add" marks without going above "full" or

CAUTION: Do not overfiU the crankcase.

It may result in oil-fouled spark plugs, oil leaks caused by oil seal failure, or engine damage due to foaming of the oil.

MANUAL TRANSMISSION FLUID

Remove the filler plug from the side of the transmission (the upper plug if the transmission has two plugs). The oil should be level with the bottom edge of the filler hole. This should be checked at least once every 6,000 miles and more often if any leakage or seepage is observed. Fill with SAE 80 or 90 multipurpose gear lubricant.

NOTE: The 4 speed overdrive transmis-

sion uses two types of fluid. See "Lubrication" for details.

below "add."

Page 27

GENERAL INFORMATION AND MAINTENANCE 23

AUTOMATIC TRANSMISSION FLUID

Run the engine until it reaches normal operating temperature. Park the car on a level surface. With the transmission in Park and the engine idling, the fluid level on the dipstick should be between the "foil" mark and Vt inch below "foil" mark. Repkce the dipstick making sure that it is pushed folly into the filler tube.

CAUTION: Do not overfill the automatic

transmission. Use Dexron® or Type A automatic transmission fluid or any other equivalent fluid. One pint raises the level from' 'add'to"full"

(65 -85'F.) (18 -29 C.)

COOL HOT

ADD 1 PT.—J ° <,

NOTE: DO NOT OVERf ILL. It

takes only one pint to raise level from ADD to FULL with a hot transmission.

Automatic transmission dipstick

i—FULL HOT

BRAKE MASTER CYLINDER

Once every 6,000 miles or four months, check the brake fluid level in the master cylinder. The master cylinder is mounted on the firewall and is divided into two reservoirs and the fluid level in each reservoir must be maintained at V4 inch below the top edge. Use only heavy-duty brake fluid (DOT 3 or 4), which is recommended for disc brake applications. See "Brakes" for details.

neck, or the line on expansion tank-equipped models.

CAUTION: Allow the engine to cool con-

siderably and then add water while the engine is running.

STANDARD REAR AXLE

The rear axle oil level should be checked when the chassis is lubricated. Remove the plug from the side of the housing. The lubricant level should be maintained at the bottom of the filler plug hole. When repkcing oil, use SAE 80 or 90 multipurpose hypoid gear lubricant.

POSITRACTION REAR AXLE

Lubricant level should be checked at each

chassis lubrication and maintained at the bot-

tom of the filler plug hole. Special Positrac-

tion oil must be used in this differential.

CAUTION: Never use standard differential

lubricant in a Positractton differential.

MANUAL STEERING GEAR

Check the lubricant by removing the center bolt on the side cover of the steering gear. Grease must be up to the level of this bolt hole.

POWER STEERING RESERVOIR

Maintain the proper fluid level as indicated on the cap of the reservoir. Check this level with the engine off and warm. Use GM power steering fluid or its equivalent. Note: Avoid

using automatic transmission fluid in power steering units except in an emergency.

Checking the master cylinder fluid level

LEVEL CYLINDER

Power steering dipstick

COOLANT

Check the coolant level when the engine is cold. The level of coolant should be maintained 2 in. below the bottom of the filler

Tires

INFLATION PRESSURE

Tire inflation is the most ignored item of auto maintenance. Gasoline mileage can drop as

Page 28

24 GENERAL INFORMATION AND MAINTENANCE

454

350

4.0

8©

Year

1963

1964

1965

1966

1967

1968

1969

1970

1971

Engine

Model (cu

In.) ©

327 (hyd.

Crankcase

Add 101 for

New Filter

lifters) 327 HP (solid

lifters) 327 (hyd.

lifters) 327 HP (solid

lifters) 327 (hyd.

lifters) 327 (solid

lifters) 327 (300

hp)

327 HP

(350 hp) 427 5

327 (300 hp)

327 HP (350 hp)

4 5

427 5

427 HP 327 (300

hp) 327 HP

(350 hp)

5 4

427 5

427 HP 350 (all)

5 4

427 5

427 HP 350 (all) 454 (all)

350 (270 hp)

350 HP (330 hp)

5 4 5 4

454 5

454 HP

Capacities & Pressure

Transmission Pts to Refill after Draining

Manual

3-spd 4-spd

2 2.5 — 2.5 2 2.5 — 2.5

2 2.5 2 2.5 3 3.0 — 3.0 — 3.0

3 3.0 — 3.0 — 3.0

— 3.0 3 3.0

— 3.0 — 3.0

— 3.0 — 3.0 — 3.0 — 3.0 — 3.0 — 3.0 — 3.0

— 3.0 — 3.0

— 3.0

Automatic

18 3.7 20 17 13

— 3.7 20 17 13

18 3.7 20 17 13

— 3.7 20 17 13

18 3.7 20 17 13 18 3.7 20 17 13 18 3.7 20 19 15

— 3.7 20 19 15 — 3.7 20 22 15

19 3.7 20 19 15

— 3.7 20 19 15

19 3.7 20 22 15

— 3.7 20 22 15

22 3.7 20 15 15

— 3.7 20 15 15

22 3.7 20 22 15

— 3.7 20 22 15 8® 4.0 20 15 15 8© 4.0 20 22 15 8© 4.0 20 22 15 8® 4.0 20 ® 15 22 4.0 20 22 15 22 4.0 18 15 15

— 4.0 18 18 15 22 4.0 18 22 15

22 4.0 18 20 15

(pts)

Fuel

Tank

(gai)

Cooling System

(qts)

Max

Coolant

Pressure

(psi)

1972 350 (all)

— 3.0

22 4.0 18 ® 15

Page 29

1973

454 8© 18 24 15 4.0

— 3.0

Is"

Page 30

GENERAL INFORMATION AND MAINTENANCE 25

1984®

20 15 15

Model

Year

1974

1975-76

350 4

1977

350 4

1978

350 4

1979 1980 1981

350 4

1982

350 4

® "HP" denotes high performance engine; "hp" denotes horsepower © For pan removal and filter change only © 15 qts. for standard engine, 18 qts. with special high performance (L82) engine ® With automatic transmission and air conditioning add 1 qt. © With optional close-ratio transmission, subtract 1A qt. ® See "Manual Transmission" for details on 4 speed overdrive

(cuin.)©

350 4

454 5

350.

305, 350

—

350

Capacities & Pressure (cont.)

Transmission Pis to Refill

Engine

Crankcase

Add 1 at far

New Filler

3-spd 4 -spd

— 3.0 — 3.0 — 3.0 — 3.0 — 3.0

— 3.0®

— —

4.0

after Draining

Manual

Automatic

8® 4.0 18 17 17 8® 4.0 18 22 23 8© 4.0 18 17 17 8© 6©

6© 6® 4.0 24 21® 15 6® 4.0 24 21® 15

10© 4.0 24 21® 15

10®

Fuel Tank (gal)

(pts)

3.75

17 21 15

3.75

4.0

Cooling System

(qts)

21.6

Max

Coolant

Pressure

(psl)

much as .8% for every 1 pound per square inch (psi) of under inflation.

Two items should be a permanent fixture in every glove compartment; a tire pressure gauge and a tread depth gauge. Check the tire air pressure (including the spare) regularly with a pocket type gauge. Kicking the tires won't tell you a thing, and the gauge on the service station air hose is notoriously inaccurate.

The tire pressures recommended for your car are usually found on the glove-box door or in the owner's manual. Ideally, inflation pressure should be checked when the tires are cool. When the air becomes heated it expands and the pressure increases. Every 10° rise (or drop) in temperature means a difference of 1 psi, which also explains why the tire appears to lose air on a very cold night. When it is impossible to check the tires "cold," allow for pressure build-up due to heat. If the "hot" pressure exceeds the "cold" pressure by more than 15 psi, reduce, your speed, load or both. Otherwise internal heat is created in the tire. When the heat approaches the temperature at which the tire was cured, during manufacture, the tread can separate from the body.

CAUTION: Never counteract excessive

pressure build-up by bleeding affair pressure (letting some air out.) This will only

further raise the tire operating temperature.

Before starting a long trip with lots of luggage, you can add about 2—4 psi to the tires to make them run cooler, but never exceed the maximum inflation pressure oil the side of the tire.

TREAD DEPTH

All tires made since 1968, have 8 built-in tread wear indicator bars that show up at W wide smooth bands across the tire when Vie" of

Tread wear Indicators will appear when the tire Is worn out

Page 31

26 GENERAL INFORMATION AND MAINTENANCE

tread remains. The appearance of tread wear indicators means that the tires should be replaced. In feet, many states have laws prohibiting the use of tires with less than Vie" tread. You can check your own tread depth with an inexpensive gauge or by using a Lincoln head penny. Slip the Lincoln penny into several tread grooves. If you can see the top of Lincoln's head in 2 adjacent grooves, the tires have less than Vie" tread left and should be replaced. You can measure snow tires in the same manner by using the "tails" side of the

Tread depth can be checked with an Inexpensive gauge

A penny works as weli as anything for checking tread depth; If the top of Lincoln's head Is vlsable In two or more adjacent grooves, the tires should be replaced

Lincoln penny. If you can see the top of the Lincoln memorial, it's time to replace the snow tires.

TIRE ROTATION

Tire wear can be equalized by switching the position of the tires about every 6000 miles. Including a conventional spare in the rotation pattern can give up to 20% more tire life. CAUTION: Do not include the new "Space-

Saver®' or temporary spare tires in the rotation pattern.

There are certain exceptions to tire rotation, however. Studded snow tires should not be rotated, and radials should be kept on the same side of the car (maintain the same direction of rotation). The belts on radial tires get set in a pattern. If the direction of rotation is reversed, it can cause rough ride and vibration.

NOTE: When radials or studded snows are

taken off the car, mark them, so you can

maintain the same direction of rotation.

BIAS PLY TIRE 4-

WHEEL ROTATION

BIAS PLY TIRE S-

WHEEL ROTATION

Tire rotation diagrams; note that radlals should not be cross-switched

RADIAL PLY TIRES

4-WHEEL ROTATION

RADIAL PLY TIRES

5-WHEEL ROTATION

Page 32

GENERAL INFORMATION AND MAINTENANCE 27

TIRE STORAGE

Store the tires at proper inflation pressures if they are mounted on wheels. All tires should be kept in a cool, dry place. If they are stored in the garage or basement, do not let them stand on a concrete floor; set them on strips of wood.

ALUMINUM WHEELS

CAUTION: If your vehicle has aluminum wheels, whether they are the early "turbine" style or the late (76 and up) slotted style, be VERY careful when using any type of cleaner on either the wheels or the tires. Read the label on the package of the cleaner to make sure that it will not damage aluminum.

An optional knock-off wheel was introduced with the 1963 Stingray. This wheel option consisted of 15 x 6L cast aluminum wheels, knock-off locking nuts, and wheel adapters. The latter bolt to the hub, using the existing wheel hub bolts. The flange of the adapter had five pins that fitted into corresponding holes in the optional wheels and located the wheel to the hub. The securing device was the single, center, knock-off nut.

Each Corvette delivered with the optional, knock-off aluminum wheels, was equipped with a special knock-off hammer. Owners of these cars were urged to tighten the knockoff nut every 100 miles for the first 500 miles. The suggested method was to strike the ears of the nut eight hard blows.

Should adapter pin replacement become necessary, remove the wheel and tire assembly and remove the adapter from the wheel hub. Select a socket of suitable size that will

Knock-off wheel adapter

Removing adapter pin

slip over the adapter pin. Position the socket over the back of the pin and clamp the entire assembly in a vise so that the socket acts as a spacer to receive the damaged pin. Tighten the vise and press the pin from the adapter. Position the replacement pin and start it into the hole by tapping lightly. Position the spacer socket on the opposite side and again clamp the assembly in the vise. Press the replacement pin into the adapter. Check to see that it seats firmly against its bore. Install the adapter and wheel.

NOTE: The optional 16 in. cast aluminum

wheels on 1984 models are designated for right, left, front or rear installation depending on the cooling fins. Rear wheels are one inch wider than the front.

Fuel Filter

The filter in Carter WCFB, Rochester Quadrajet, Holley 2300, and Holley 4150 carburetors is located in the fuel inlet connection and should be replaced at least every 12,000 miles or sooner if engine flooding occurs. The Carter AFB uses an in-line filter, which should be replaced every 24,000 miles. The Rochester and Throttle Body fuel injection uses an in-line filter, which should be replaced every 15,000 miles.

To replace an in-line filter, disconnect the fitting at each end of the filter canister, discard the old filter, and install the replacement in the reverse order of removal.

To replace a fuel inlet filter:

1. Using an open-end wrench (preferably a line wrench), disconnect the fuel line con nection from the larger fuel filter nut.

2. Remove the larger nut from the carbu retor.

Page 33

28 GENERAL INFORMATION AND MAINTENANCE

Most late models have this bronze fuel filter lo

rolet recommends doing this for vehicles which see severe usage (racing, etc.), it is also a wise move for street-driven vehicles. The small, carburetor mounted filter clogs more easily than a large in-line filter. The clogged filter can cause a drastic drop in fuel pressure which will generally cause the engine to run leaner; engine damage can result from an excessively lean fuel mixture. Another negative view of a carburetor mounted filter is that if a fuel pressure problem is encountered, a clogged carburetor mounted filter would not show a pressure loss during a fuel pressure

Inline fuel filter

3. Remove the filter element and spring

from the carburetor.

4. Check the bronze element for dirt blockage by blowing on the cone end. If the element is good, air should pass through eas-

fly.

5. If the car has a paper element instead of a bronze element, check by blowing into the fuel inlet end. If air does not pass through easily replace the element. Do not attempt to clean these elements.

6. Install the spring and then the element into the carburetor, making sure that the small end of the bronze cone is facing out ward.

7. Install a new gasket on the large nut and tighten securely.

8. Insert the fuel line and tighten the nut with a line wrench.

If your vehicle is equipped with a small filter mounted in die carburetor fuel inlet, it may be wise to consider replacing this filter with a larger "in-line" filter. Although Chev-

test since the filter is mounted after the fuel pressure test connection. In-line fuel filters are relatively inexpensive and easy to install. The added filtering protection and longer filter life offered by the in-line filter more than make up for its slight additional cost.

NOTE: Do not perform this operation on

1976 and later models, as special fuel filters with anti-spillage valves are used. If you

decide to install an in-line fuel filter, first remove and discard the carburetor mounted filter. Position the in-line fuel filter against the fuel line to judge where the fuel line has to be cut. Do not mount the in-line filter straight up as this could allow fuel vapors to block the filter outlet (vapor-lock). Preferably, the filter should be mounted on a 45° angle and be positioned an inch away from surrounding engine components. Mark where the fuel line must be cut, disconnect the line from the fuel pump and remove the fuel line. Using either a "mini" tubing cutter or a hack-

cated behind the fuel fitting

1. Carburetor fitting

2. Cut fuel line here

3. Fuel-resistant connecting hoses

4. Install clamps here

5. Fuel pump fitting

Typical in-line fuel filter installation

Page 34

Maintenance

1963-67

Maintenance Intervals

1968- 71

1972-74 1975-79

1980-84

bath Paper elem ent © PCV Valve (Replace) 12 mo/1 2,000 mi 12 mo/1 2,000 mi 12 mo/1 2,000 mi 15,000 mi

12,000 mi 1 2,000 mi

(replace)

—

Replace filter

Check Replace Engine Oil Filter (Replace) every oil change every oil change every oil change every oil change every oil change

Replace 12,000 mi 12,000 mi 12,000 mi 15,000 mi 15,000 mi. Check Replace

Each fuel stop 4

mo/6,000 mi

6,000 mi

24,000 mi

12,000 mi (replace) 24,000 mi (replace) 30,000 mi (replace)

12 mo/1 2,000 mi.

(1970-71)

each fuel stop 4

mo/6,000 mi

6,000 mi

24,000 mi

12 mo/1 2,000 mi 24 mo/30,000 mi 24 mo/30,000 mi.

each fuel stop 4

mo/6,000 mi

each fuel stop 6

mo/7,500 mi

— — —

30,000 mi (replace)

30,000 mi.

each fuel stop 12 mo/7500 mi.®

—

Turbo Hydra-Matic Fluid & Filter Check fluid Change fluid Replace

Check lubricant Add lubricant

Battery Lubricate terminal felt washer Clean terminals Check electrolyte level Coolant level Each fuel stop each fuel stop each fuel stop each fuel stop each fuel stop

6,000 mi as

necessary

6,000©

6,000 mi Twice

monthly

6,000 mi

24,000 mi 24,000 mi

6,000 mi as

necessary

6,000©

6,000 mi twice

monthly

6,000 mi

24,000 mi 24,000 mi

6,000 mi as

necessary

as necessary twice monthly

6,000 mi

30,000 mi 30,000 mi

7,500 mi as

necessary

as necessary

twice monthly ®

each eng. oil change 100,000 mi.® 100,000 mi.®

7500 mi. as necessary

as necessary not necessary

z m

> o

z m

o m

Lubricate 24,000 mi 24,000 mi 24,000 mi 30,000 mi 30,000 mi

l Bearings

Page 35

30 GENERAL INFORMATION AND MAINTENANCE

" c (fl

g>0) 0) §

•5 "5

CO m

,§•

O C

Cu (A

- c 10

-s

_g 'cr

* 1 -

Page 36

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GENERAL INFORMATION AND MAINTENANCE 31

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Page 37

32 GENERAL INFORMATION AND MAINTENANCE

saw with a fine-toothed blade, cut the fuel line and make sure to clear the line of metal particles left from the cutting. Reinstall the line but do not yet tighten the fittings. Install the in-line filter (if the filter is marked "in" and "out," install the "out" side towards the carburetor), fuel-resistant connecting hoses, and the clamps. Tighten the hose clamps and the fuel line fittings at the fuel pump and carburetor. Start the engine and check for leaks.

LUBRICATION

Oil and Fuel Recommendations

For 1980 and earlier vehicles, oils having one of the following service ratings MUST be used: SE, SE/CC, or SF. For 1981 and later vehicles, use ONLY SF rated oils; it is O.K. to use an SF oil with a combination rating, such as SF/CC. Under the classification system developed by the American Petroleum Institute, the SF rating designates the highest quality oil for use in passenger cars. In view of this, it is recommended that you use an SF rated oil an ANY Corvette. In addition, Chevrolet recommends the use of an SF/Energy Conserving oil. Oils labeled "Energy Conserving (or Saving)," "Fuel (Gas or Gasoline) Saving," etc. are recommended due to their superior lubricating qualities (less friction = easier engine operation) and fuel saving characteristics. Pick your oil viscosity with regard to the anticipated temperatures during the period before your next oil change. Using the accompanying chart, choose the oil viscosity for the lowest expected temperature. You will be assured of easy cold starting and sufficient engine protection.

NOTE: Some fuel additives contain chem-

icals that can damage the catalytic converter and/or oxygen sensor on late model engines. Read all labels carefully before using any additive in the engine or fuel system.

Fuel should be selected for the brand and octane which performs best with your engine. Judge a gasoline by its ability to prevent "pinging," its engine starting capabilities (cold and hot), and general all-weather performance. As far as octane rating is concerned, refer to the "General Engine Specifications" chart in Chapter 3 to find your engine and its compression ratio. If the compression ratio is 9.0:1 or lower, in most cases a regular grade of gasoline can be used.

Oil Viscosity Selection Chart

Multigrade

Singlegrade

Anticipated Temperature Range

Above 32°F

May be used as low as -10°F

Consistently below 10°F

Above 32°F

Temperature between +32°Fand -10°F

SAE

Viscosity

10W-

10W20W20W-

10W-30

10W-

10W-40

5W5W-30

10W

If the compression ratio is 9.0:1-10.0:1, use a

premium grade of fuel. Vehicles with a compression ratio higher than 10.0:1 (1970 and prior—check the engine chart) should use a premium leaded fuel, if it is available. Most oil companies have discontinued leaded pre-

mium gasoline; if you cannot find leaded premium, it has been recommended by several enthusiast publications to mix regular leaded

and unleaded premium in a 1:3 proportion (1 part regular leaded to 3 parts unleaded premium). This mixture will give you the lubricating properties of lead and the added performance of a premium gasoline. Also, mixing

leaded and unleaded fuels will increase the

total octane rating by 1 or more points, de-

pending on the ratings of the gas which is ac-

tually used. DO NOT use straight unleaded

gas in a vehicle designed to use leaded; ex-

cessive valve and valve seat wear will result.

CAUTION: Unleaded fuel MUST be used

in 1975 and later vehicles equipped with catalytic converters. Use of leaded fuel in these vehicles will render the catalytic con-

verter ineffective and damage the oxygen

sensor, if equipped.

Fluid Changes

ENGINE OIL AND FILTER

The mileage figures given in your owner's manual are the Chevrolet recommended intervals for oil and filter changes assuming average driving. If your Corvette is being used under dusty, polluted, or off-road conditions, change the oil and filter sooner than specified. The same thing goes for cars driven in stop-and-go traffic or only for short distances. Always drain the oil after the engine has

Page 38

GENERAL INFORMATION AND MAINTENANCE 33

been running long enough to bring it to operating temperature. Hot oil will flow easier and more contaminants will be removed along with the oil than if it were drained cold. You will need a large capacity drain pan, which you can purchase at any store which sells automotive parts. Another necessity is containers for the used oil. You will find that plastic bottles, such as those used for bleach or fabric softener, make excellent storage jugs. One ecologically desirable solution to the used oil disposal problem is to find a cooperative gas station owner who will allow you to dump your used oil into his tank. Another is to keep the oil for use around the house as a preservative on fences, railroad tie borders, etc.

Chevrolet recommends changing both the oil and filter during the first oil change and the filter every other oil change thereafter. For the small price of an oil filter, it's cheap insurance to replace the filter at every oil change. One of the larger filter manufacturers points out in its advertisements that not changing the filter leaves one quart of dirty oil in the engine. This claim is true and should be kept in mind when changing your oil.

CHANGING YOUR OIL

1. Run the engine until it reaches normal

operating temperature.

2. Jack up the front of the car and sup

port it on safety stands.

3. Slide a drain pan of at least 6 quarts

capacity under the oil pan.

4. Loosen the drain plug. Turn the plug out by hand. By keeping an inward pressure on the plug as you unscrew it, oil won't es cape past the threads and you can remove it without being burned by hot oil.

NOTE: Dispose of waste oil properly; don't

pollute the environment. Avoid prolonged skin contact with used oil either directly or from oil-saturated clothing.

5. Allow the oil to drain completely and

then install the drain plug. Don't overtighten the plug, or you'll be buying a new pan or a trick replacement plug for damaged threads.

6. Using a strap wrench, remove the oil filter. Keep in mind that it's holding about one quart of dirty, hot oil.

1963-67 Corvettes use a cartridge type oil filter. On these models, loosen the center bolt on the filter housing and remove the housing along with the filter. If possible, replace the housing-to-block seal during installation and do not overtighten the housing bolt. Aftermarket adaptors are available to adapt the new

style spin-on filters to earlier engines. Some prefer the convenience of a spin-on filter, though the cartridge type filter actually offers a greater filtering area.

7. Empty the old filter into the drain pan

and dispose of the filter.

8. Using a clean rag, wipe off the filter adapter on the engine block. Be sure that the rag doesn't leave any lint which could clog an oil passage.

9. Coat the rubber gasket on the filter with fresh oil. Spin it onto the engine by hand; when the gasket touches the adapter surface give it another Vz-% turn. No more, or you'll squash the gasket and it will leak.

10. Refill the engine with the correct amount of fresh oil. See the "Capacities" chart.

11. Crank the engine over several times and then start it. If the oil pressure gauge shows zero, shut the engine down and find out what's wrong.

12. If the oil pressure is OK and there are no leaks, shut the engine off and lower the car.

13. Wait a few minutes and check the oil level. Add oil, as necessary, to bring the level up to Full.

MANUAL TRANSMISSION

No intervals are specified for changing the transmission lubricant, but after extended heavy duty operation it may be a good idea. The vehicle should be on a level surface and the lubricant should be at operating temperature.

1. Position the vehicle on a level surface.

2. Place a pan of sufficient capacity under

the transmission drain plug.

3. Remove the upper (fill) plug to provide

a vent opening.

4. Remove the lower (drain) plug and let

the lubricant drain out.

5. Replace the drain plug.

6. Add lubricant with a suction gun or squeeze bulb. The correct lubricant is SAE 80W-90 GL-5 Gear Lubricant, or SAE SOW GL-5 for cold climates. Refer to the Capaci ties and Pressures Chart for the correct quan tity.

AUTOMATIC TRANSMISSION

NOTE: The fluid should be drained while

the transmission is warm.

1. Using a jack, raise the front of the ve-

hicle and support it safely with jackstands. If the transmission pan has no drain plug, visu-

Page 39

34 GENERAL INFORMATION AND MAINTENANCE

ally check that you can gain access to all of the transmission pan bolts. If you can, proceed to step 8; if not, proceed to step 2.

2. Place a jack under the transmission with a block of wood (a piece of a 2x4 will do) between the jack and the transmission pan.

3. Raise the jack until the wood block contacts the transmission pan.

4. Remove the crossmember -to-transmission mount bolts and the crossmemberto-frame bolts.

5. Raise the transmission SLIGHTLY— just enough to take the weight of the trans mission off of the crossmember.

6. Turn the crossmember sideways and remove it.

7. Place a jackstand close to the transmis sion tailshaft. Lower the jack until the trans mission rests on the stand. Remove the jack and the wood block.

8. Place a drain pan under the transmis sion pan. If the pan has a drain plug, remove it and allow the fluid to drain.

9. If the pan does not have a drain plug, remove the pan bolts from one side of the pan and loosen the rest of the bolts. This will allow the pan to partially drain. Remove the remaining pan bolts and carefully lower the pan away from the transmission.

NOTE: If the transmission fluid is dark or

has a burnt smell, transmission damage is indicated. Have the transmission checked professionally. CAUTION: If the pan sticks, carefully tap sideways on the pan with a rubber mallet or a plastic hammer to break the pan loose. DO NOT dent the pan. Avoid prying the pan off with a screwdriver—this can bend the pan or crack the transmission case.

10. Empty the pan, remove the gasket material, and clean the pan with solvent (car buretor cleaner works well).

11. Remove any gasket material which may remain on the transmission case.

12. Remove the transmission filter from the valve body. The filter may have either a fi brous or screen filtering element and is re tained by one or two fasteners.

13. Install a new filter using a new gasket or O-ring (TH400's).

NOTE: If the transmission uses a filter

having a fully exposed screen, it may be cleaned and re-used.

14. Install the pan using a new gasket. Tighten the bolts to 12-14 ft. Ibs. in a criss cross pattern. Recheck the bolt torque after all of the bolts have been tightened once.

15. Add either Dexron or Dexron II trans mission fluid through the filler tube. See the Capacities Chart to determine the proper amount of fluid to be added.

CAUTION: DO NOT OVERFILL the

transmission; foaming of the fluid and subsequent transmission damage due to slippage will result.

16. With the gearshift lever in PARK, start die engine and let it idle. Do not race the engine.

17. Move the gearshift lever through each position, holding the brakes. Return the le ver to PARK, and check the fluid level with the engine idling. The level should be be tween the two dimples on the dipstick, about Vs. in. below the ADD mark. Add fluid, if necessary.

18. Check the fluid level after the vehicle has been driven enough to thoroughly warm up the transmission. Details are given under Fluid Level Checks earlier in the Chapter. If the transmission is overfilled, the excess must be drained off-

REAR AXLE

Refer to the Maintenance Intervals chart for information on when to change the fluid.

1. Run the vehicle so the lubricant reaches

operating temperature.

2. Position a drain pan under the rear axle.

3. Remove the axle housing cover and gas

ket and drain the lubricant.

4. Clean the gasket sealing surfaces and

install the cover with a new gasket.

5. Torque the cover bolts in a crosswise

pattern to 20 ft. Ibs.

6. Add 4 oz. of rear axle lubricant additive

(GM 1052358).

7. Use a suction gun or a squeeze bulb and refill the differential housing to a level within %" of the filler plug with rear axle lubricant (GM 1052271) or equivalent. (See the Capac ities Chart),

8. Install the filler plug.

COOLANT

Refer to the Cooling System Section under Routine Maintenance. Observe the recommended specifications for aluminum, if necessary.

Chassis Greasing

Chassis greasing can be performed with a pressurized grease gun or it can be performed at home by using a hand-operated

Page 40

GENERAL INFORMATION AND MAINTENANCE 35

LUBRICATE EVERY 6,000 MILES

REPLACE EVERY 24,000 MILES

LUBRICATE EVERY 34,000 MILES

* REFILL POSITRACTION REAR AXLE

WITH SPECIAL LUBRICANT ONLY

GL-MULTI-PURPOSE OR

UNIVERSAL GEAR

LUBRICANT*

WB-WHEEL BEARING LUBRICANT

Lubrication points—1963 -74

grease gun. Wipe the grease fittings clean before greasing in order to prevent the possibility of forcing any dirt into the component.

Wheel Bearings

Once every 24,000 miles, clean and repack wheel bearings with a wheel bearing grease. Use only enough grease to completely coat the rollers. Remove any excess grease from the exposed surface of the hub and seal.

It is important that wheel bearings be properly adjusted after installation. Improperly adjusted wheel bearings can cause steering instability, front-end shimmy and wander, and increased tire wear. For complete adjustment procedures, see the "Wheel Bearing" section in Chapter 8.

CL-CHASSIS LUBRICANT

TRANSMISSION FLUID

BF-BRAKE FLUID

S AT-DEXRON AUTOMATIC

PUSHING AND TOWING

Corvettes equipped with either the Powerglide or Turbo Hydra-Matic automatic transmissions cannot be push-started. To pushstart a Corvette that has either a three-speed or four-speed manual transmission, switch on the ignition, select the highest forward gear and keep the clutch pedal depressed until suitable speed has been provided by the pushing vehicle. When this speed, approximately 15 mph, is reached, slowly release the clutch to start the engine.

Corvettes may be towed at speeds up to 35 mph and distances not over 50 miles with the driveshaft in place, if no engine/drive-line damage is present. If engine/drive-line damage is known or suspected, the driveshaft should be disconnected before towing. Towing connections should not be made on

Page 41

36 GENERAL INFORMATION AND MAINTENANCE

LUBRICATE EVERY7.500MILES LUBSICATE FIRST 12,000 MILES

REPLACE EVERY 30,000«ILtS

CHECK FOR GREASE LEAKAGE

EVERY 30,000 MILES

REFILL POSITRACTION REAR AXLE

WITH SPECIAL LUBRICANT ONLY

1. Front suspension

2. Steering linkage

3. Steering gear

4. Air cleaner

5. Front wheel bearings

6. Transmission

GL-MULTI-PURPOSE OR

UNIVERSAL GEAR

LUBRICANT'

WB-WHEEL BEARING LUBRICANT

7. Rear axle

8. Oil filter

9. Battery

10. Parking brake

11. Brake master cylinder

12. Rear wheel inner bearing

CL-CHASSIS LUBRICANT

AT-DEXRON-H® AUTOMATIC TRANSMISSION FLUID

BF-BRAKE FLUID SG-STEERING

GEAR LUBRICANT

Lubrication points—1975-82 typical

Front towing point Rear towing point

Page 42

GENERAL INFORMATION AND MAINTENANCE 37

bumpers, only on the spindle struts at the rear and the frame crossmember or lower control arm at the front.

JUMP STARTING

The following procedure is recommended by the manufacturer. Be sure that die booster battery is 12 volt with negative ground. CAUTION: Do not attempt this procedure

on a frozen battery; it will probably explode. Do not attempt it on a sealed Delco Freedom battery showing a light color in the charge indicator. Be certain to observe correct polarity connections. Failure to do so will result in almost immediate alternator and regulator destruction. Never allow the jumper cable ends to touch each other.

1. Position the 2 vehicles so that they are not touching. Set the parking brake and place automatic transmissions in Park and manual transmissions in Neutral. Turn of the lights, heater and other electrical loads.

2. Remove the vent caps from both the booster and discharged battery. Lay a cloth over the open vent cells of each battery. This isn't necessary on batteries equipped with sponge type flame arrestor caps, and it isn't possible on sealed Freedom batteries.

3. Attach one cable to the positive (+) ter minal of the booster battery and the other end to the positive terminal of the discharged bat tery.

4. Attach one end of the remaining cable to the negative (—) terminal of the booster battery and the other end to the alternator bracket. Do not attach to the negative ter minal of discharged batteries.

5. Start the engine of the vehicle with the booster battery. Start the engine of the vehi cle with the discharged battery. If the engine will not start, disconnect the batteries as soon as possible. If this is not done, the two bat teries will soon reach a state of equilibrium, with both too weak to start an engine. This will not be a problem if the engine of the booster vehicle is kept running fast enough. Lengthy cranking can also overheat and dam age the starter.

6. Reverse the above steps to disconnect the booster and discharged batteries. Be cer tain to remove negative connections first.

7. Reinstall the vent caps. Dispose of the cloths; they may have battery acid on them.

CAUTION: The use of any "hot shot" type

of jumper system in excess of 12 volts can damage the electronic control units on late model engines with computer controls.

JACKING AND HOISTING

The jack supplied with the Corvette was meant for changing tires. It was not meant to support a vehicle while you crawl under it and work. Whenever it is necessary to get under a vehicle to perform service opera-

DRIVE-ON HOIST, TWO-POST HOIST

WITH DRIVE-ON ADAPTORS

FLOOR JACK, JACKSTANDS,

CENTER POST HOIST

Jacking and hoisting points

JACK STANDS

Page 43

38 GENERAL INFORMATION AND MAINTENANCE

tions, always be sure that it is adequately supported, preferably by jackstands at the proper points. Always block the wheels when changing tires.

Since the Corvette is equipped with a Positraction rear axle, do not run the engine for any reason with one rear wheel off the ground. Power will be transmitted through the rear wheel remaining on the ground, possibly causing the vehicle to drive itself off the jack.

Some of the service operations in this book require that one or both ends of the vehicle be raised and supported safely. The best arrangement for this, of course, is a grease pit or a vehicle lift, but these items are seldom found in the home garage. However, small hydraulic, screw, or scissors jacks are satisfactory for raising the vehicle.

Heavy wooden blocks or adjustable jackstands should be used to support the vehicle while it is being worked on. Drive-on trestles, or ramps, are also a handy and a safe way to raise the vehicle, assuming their capacity is adequate. These can be bought or constructed from suitable heavy timbers or steel.

In any case, it is always best to spend a

little extra time to make sure that your Corvette is lifted and supported safely.

CAUTION: Concrete blocks are not rec-

ommended. They may crumble if the load is not evenly distributed. Boxes and milk crates of any description must not be used. Shake the vehicle a few times to make sure the jack stands are securely supporting the weight before crawling under.

Page 44

Tune-Up and

COLDER

HOTTER

Spark plug heat range, the higher the number the

hotter the plug

Performance Maintenance

TUNE-UP PROCEDURES

This section gives specific procedures on how to tune-up your Corvette. It is intended to be as complete and as basic as possible. Those who are familiar widi die steps involved in a tune-up may wish to slap die following procedures and use die generalized section in chapter 10. However, it is felt that nothing would be lost by first reading over tins section. Perhaps the best procedure to follow would be to read botii sections before starting your tune-up.

Spark Plugs

A typical spark plug consists of a metal shell surrounding a ceramic insulator. A metal electrode extends downward through the center of die insulator and protrudes a small distance. Located at the end of the plug and attached to die side of die outer metal shell is the side electrode. The side electrode bends in at a 90° angle so diat its tip is even witii, and parallel to, the tip of the center electrode. The distance between diese two electrodes (measured in tiiousandths of an inch) is called the spark plug gap. The spark plug in no way produces a spark but merely provides a gap across which the current can arc. The coil produces anywhere from 20,000 to 40,000 volts which travels to die distributor where it is distributed through die spark plug wires to die spark plugs. The current passes along die center electrode and jumps die gap to die side electrode, and, in so doing, ignites die air/fuel mixture in die combustion chamber.

die fartiier it extends into die engine), die hotter the plug will operate; the shorter the insulator die cooler it will operate. A plug tiiat absorbs littie heat and remains too cool will quickly accumulate deposits of oil and carbon since it is not hot enough to burn diem off. This leads to plug fouling and consequendy to misfiring. A plug diat absorbs too much heat will have no deposits, but, due to die excessive heat, die electrodes will burn away quickly and in some instances, preignition may result. Preignition takes place when plug tips get so hot diat diey glow sufficiendy to ignite die fuel/air mixture before die actual spark occurs. This early ignition will usually cause a pinging during low speeds and heavy loads.

The general rule of tiiumb for choosing die correct heat range when picking a spark plug is: if most of your driving is long distance, high speed travel, use a colder plug; if most of your driving is stop and go, use a hotter plug. Original equipment plugs are compromise plugs, but most people never have oc-

SPARK PLUG HEAT RANGE

Spark plug heat range is the ability of die plug to dissipate heat. The longer die insulator (or

Page 45

40 TUNE-UP AND PERFORMANCE MAINTENANCE

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Page 47

Year

1971

1972

1973

1974

1975-76

1977

1978

1979

Tune-Up Specifications (cont.)

Spark Plugs

Model

270 hp 330 hp

365 hp 425 hp

R44®

200 hp

R44T

255 hp

R44T

270 hp

R44T

190hp

R44T

250 HP

R44T

270 hp

R44T

195hp

R44T

250 hp

R44T

270 hp

R44T

165 hp

R44TX

205 hp

R44TX

180 hp

R45TS

210hp

R45TS

185 hp

R45TS

220 hp

R45TS

195 hp

R45TS

225 hp

R45TS

Type

R44TS R43TS

R43TS

Gap

(In.)

0.035

0.035 29-31 0.019

0.035

0.035 28-30 0.019

0.035

0.060

0.045

Distributor

Point Point Dwell Gap (deg) (In.)

28-32 0.019

Transistor

Ignition

28-32 0.019

Transistor

Ignition

29-31 0.019

29-31 0.019 29-31 0.019 29-31 0.019 29-31 0.019 29-31 0.019 29-31 0.019

Electronic Electronic

Electronic Electronic Electronic Electronic Electronic Electronic

Valves

Basic Ignition

Timing (deg

BTDC)

Clearance (In.)

Intake Exhaust (deg BTDC)

llrtake

Idle

Speed

(rpm)

4® ® ® 26 600®

8© 0.024 0.030 36 700

8 ® ® 56 600

8 0.024 0.028 44 700

8 © © 26 800®

4 0.024 0.030 36 900

8 ® © 56 750® 12 ® ® 26© 900®® 8 ® ® 40 900®® 10 ® ® 56 900®® 8® ® ® 26© 900® 8 © © 40 900® 10 © © 56 800®

6 © © 26 800®

12 © © 40 900®

8 ® ® 26 800®

12 ® © 40 900®

6© © ® 26

12 ® ® 40

6© © ® 26 ®

12 ® © 40 ®

(® fiS

Normal Fuel Pressure (psl)

7V2-9

7'/2-9

7Va-9 7Va-9

7V2-9 7V2-9 7Vz-9

71/2-9 7V2-9 7V2-9

71/2-9

71/z-9 7Va-9

71/a-9 7Va-9 7V2-9

71/2-9

71/a-9 7'/2-9

71/2-9

m c

•o m

O m

o m

Page 48

1980

6 ® a

® ® a

1981 190 hp® R45TS 0.045 Electronic 1982 200 hp R45TS 0.045 Electronic 1984 205 hp R45TS 0.045 Electronic

If the specifications listed on the tune-up sticker under the hood differ from those listed here, the sticker specifications take precedence. ATDC — After top dead center BTDC — Before top dead center TDC — Top dead center ® Hydraulic lifters — one turn down from zero lash ® W/automatic transmission — 450 © W/automatic transmission — 2°ATDC ® W/automatic transmission and A.I.R. — 4°ATDC ©W/automatic transmission and A.I.R. — 700 © W/automatic transmission and A.I.R. — 750 © W/automatic transmission — 600 ® W/automatic transmission — 4°BTDC ® W/automatic transmission — 8°BTDC ® W/automatic transmission — 550 © W/automatic transmission — 12°BTDC ©California models— 44°BTDC ©California models— 4°BTDC O450 rpm w/idle solenoid disconnected ® Models with aluminum cylinder heads use A.C. R43XL ®W/automatJc transmission — 750 ©California with automatic transmission — 8°BTDC ® Use the specification listed on the tune-up sticker under the hood ©California only ©Estimated ©High altitude models with automatic transmission — 8°BTDC @ High altitude models with automatic transmission — 650 ©W/automatic transmission — 500 ram

Note: Idle speeds of automatic transmission vehicles are checked with the transmission in Drive. Note: Spark plugs listed are original equipment A.C. Delco. These listings are not recommendations by Chilton for any product by name.

180hp® (305 eng.)

190 hp (350 eng.)

230 hp (350 eng.)

R45TS 0.045 Electronic R45TS 0.045 Electronic R45TS 0.045 Electronic

4 ® a

6© ® a

12 ® a

® ® a

) 28 ® 71/a-9 ) 26 600® 71/z-9 ) 40 800 7Va-9 ) 38 700® 71/2-9

) NA ® 9-13 ) NA ® 9-13

Page 49

44 TUNE-UP AND PERFORMANCE MAINTENANCE

casion to change their plugs from the factoryrecommended heat range.

REPLACING SPARK PLUGS

Normally, a set of spark plugs requires replacement about every 10,000 miles on cars with conventional ignition systems (incl. Transistorized) and 20,000-30,000 miles on cars equipped with an H.E.I. (High Energy Ignition) system. Some earlier high performance engines may require more frequent plug changes, especially if idled or operated at low rpm's for extended periods. Any vehicle which is subjected to severe conditions will need more frequent plug replacement.

In normal operation, plug gap increases about 0.001 in. for every 1,000-2,500 miles. As the gap increases, the plug's voltage requirement also increases. It requires a greater voltage to jump the wider gap and about two to three times as much voltage to fire a plug at high speeds than at idle.

When you're removing spark plugs, you should work on one at a time. Don't start by removing the plug wires all at once, because unless you number tiiem, they may become mixed up. Take a minute before you begin and number the wires with tape. The best location for numbering is near where the wires come out of the cap.

1. Remove the radio interference shields which cover the spark plugs and wires (in some models).

2. Twist the spark plug boot and remove the boot and wire from the plug. Do not pull on the wire itself as diis will ruin the wire.

3. If possible, use a brush or rag to clean the area around the spark plug. Make sure that all the dirt is removed so that none will enter the cylinder after the plug is removed.

4. Remove the spark plug using the proper

Check the gap with a round wire gauge

size socket. (13/ie in. through 1971, % in. 1972 and later.) Turn the socket counterclockwise to remove the plug. If the engine has aluminum cylinder heads, be extremely careful when removing the plugs. If any plug turns with difficulty, spray a penetrating lubricant (Liquid Wrench, WD-40, etc.) around the plug threads and turn the plug back in. Wait a couple of minutes for the oil to work its way through the threads and then "nurse" the plug out about V-t turn at a time. Be sure to hold the socket straight on the plug to avoid breaking the plug, or rounding off the hex on the plug.

5. Once the plug is out, check it against die plugs shown in chapter 11 to determine engine condition. This is crucial since plug readings are vital signs of engine condition.

6. Use a round wire feeler gauge to check die plug gap. The correct size gauge should pass through the electrode gap with a slight drag. If you're in doubt, try one size smaller, and one larger. The smaller gauge should go through easily while the larger one shouldn't go through at all. If the gap is incorrect, use the electrode bending tool on the end of the gauge to adjust the gap. When adjusting the gap, always bend the side electrode. The center electrode is non-adjustable.

7. If die engine has cast-iron heads, squirt a DROP of penetrating oil onto die plug threads and install the plug. If the engine has aluminum heads, apply a small amount of antisieze compound to die plug threads and care fully install the plugs. Turn the plugs in by hand until diey are snug.

8. When the plug is finger tight, tighten it with a wrench.

9. Install die plug boot firmly over the plug. Proceed to the next plug.

CHECKING AND REPLACING SPARK PLUG CABLES

Visually inspect the spark plug cables for burns, cuts, or breaks in die insulation. Check die spark plug boots and die nipples on die distributor cap and coil. Replace any damaged wiring. If no physical damage is obvious, the wires can be checked widi an ohmmeter for excessive resistance. (See die tune-up and troubleshooting section.)

When installing a new set of spark plug cables, replace the cables one at a time so there will be no mixup. Start by replacing the longest cable first. Install die boot firmly over die spark plug. Route die wire exacdy die same as the original. Insert the distributor end of

Page 50

TUNE-UP AND PERFORMANCE MAINTENANCE 45

The points are retained by screws; use a mag

netic screwdriver to avoid losing them

the wire firmly into the tower on the distributor cap, then seat the boot over the tower. Repeat the process for each cable.

NOTE: Always replace the points and con-

denser together. Uniset@ points are available which combine the point set and condenser, greatly simplifying installation.

Breaker Points and Condenser

REMOVAL AND REPLACEMENT

Point alignment is preset at the factory and requires no adjustment. Point sets using the push-in type wiring terminal should be used on those distributors equipped with an R.F.I, (radio frequency interference) shield (1970—

74). Points using a lockscrew type terminal may short out due to the shield contacting the screw.

NOTE: The optional magnetic pulse dis-

tributor and the HEI (High Energy Ignition) system used on some 1974 and all 1975—79 models requies no maintenance other than checking the condition of the cap and wires. There are no points to wear out or adjust.

1. Remove the radio interference shield from around the distributor. Unlatch and re move the distributor cap.

2. Remove the rotor.

3. If so equipped, remove the two-piece R.F.I. shield.

4. Loosen the two mounting screws and slide the contact point set from the breaker plate.

5. Remove the two wires which are con nected to the point set.

6. Loosen the condenser bracket screw and slide the condenser from the bracket.

7. Install the new point set and con denser and then tighten the mounting screws.

The condenser is held In place by a screw and a damp

8. Install the wires to the terminal so that they will not interfere with the cap, weight base, or breaker advance plate. Install the half of the R.F.I. shield which covers the points first.

9. Have an assistant "tap" the ignition key to turn the engine until the rubbing block of the point set is centered on one of the distrib utor cam lobes. Turn the ignition key off.

10. Using a ¥s in. alien wrench, make an

initial point setting of 0.019 in.

11. The cam lubricator (if so equipped) must be replaced after 12 months or 12,000 miles. The end of the lubricator should be adjusted to just touch the cam lobes. Addi tional grease should not be applied to the lu bricator.

12. Install the rotor. The two lugs on the bottom of the rotor are shaped differently, so that it can only be installed one way. Tighten the screws. Start the engine and check the point dwell and the ignition timing.

Dwell Angle

Dwell angle is the amount of time (measured in degrees of distributor cam rotation) that the contact points remain closed. Initial point gap (0.019 in.) determines dwell angle. If the points are too wide they open gradually and dwell angle (the time they remain closed) is small. This wide gap causes excessive arcing at the points and, because of this, point burning. This small dwell doesn't give the coil sufficient time to build up maximu m energy and so coil output decreases. If the points are set too close, the dwell is increased but the points may bounce at higher speeds and the idle becomes rough and starting is made harder. The wider the point opening, the smaller the dwell and the smaller the gap, the larger the dwell. Adjusting the dwell by making the initial point gap setting with a feeler gauge is sufficient to

Page 51

46 TUNE-UP AND PERFORMANCE MAINTENANCE

OUTSIDE OF DISTRIBUTOR CAP

INSUFFICIENT

ROTOR INSPECTION

CLEANING IGNITION

WINDOW

WRENCH

TERMINAL

LATCH

'CONNECTOR

THIS TERMINAL

INSPECTION OF DISTRIBUTOR CAP

TOWERS

CLEANING & INSPECTION OF I

TOR TIP

CORROD

ED.

ROTOR CONTACT SPRING TENSION

______

CPU

UOWING OUT INSIDE OF DISTRIBUTOR

CAP ft INSPECTION OF INSERT

________

TERMINALS

___________

Distributor cap and rotor checkpoints

ADJUSTING \ V

SCREW ^

Adjusting point gap (dwell angle) with 1/e in. alien wrench

_______

"HEX" TYPE

get the car started but a finer adjustment should be made. A dwell meter is needed to check the adjustment.

NOTE: The ignition timing must be checked

and adjusted any time the point set is replaced or the dwell is changed. When the dwell is increased, the ignition timing decreases, and vice-versa.

1. Run the engine to normal operating

temperatures and then let it idle.

2. Raise the adjusting window on the dis tributor cap and insert a Vs in. alien wrench into the adjusting screw.

3. Turn the adjusting screw until the spec-

CLEANING 1 INSPECTION OF INSIDE OF DISTRIBUTOR CAP

REPLACING DISTRIBUTOR

CAP

_______

INSPECTION OF CAIBON I

aOTOa BUTTON I

ified dwell angle is obtained on the dwell meter.

HEI SYSTEM TACHOMETER HOOKUP

Connect one tach lead to the "TACH" terminal on the side of the distributor and the other to ground. Some tachometers must be connected to the "TACH" terminal and the battery positive terminal. Not all tachometers will operate correctly with the HEI system. Check with the manufacturer if there is any doubt.

CAUTION: The "TACH" terminal should

never be connected to ground.

IGNITION WIRE (BATTERY FEED)

(4)

CONNECT TACHOMETER Ti

Hook up one tach lead to the tachometer terminal on the HEI system

Page 52

TUNE-UP AND PERFORMANCE MAINTENANCE 47

When hooking up a remote starter switch,

disconnect the "BAIT" terminal.

Ignition Timing Adjustment

1963-80

Except 1980 California

1. Warm the engine to normal operating temperature and check the idle speed. Ad just the idle speed to specifications, if neces sary.

2. If so equipped, disconnect and plug the vacuum advance hose from the distributor.

3. Connect a timing light according to the timing light manufacturers instructions. DO

Timing mark location—typical

1. Positive (+) connection at the alternator BAT terminal

2. Negative (-) connection at a good engine

ground

12VDC timing light power connections on a typical, externally regulated Delcotron

Page 53

48 TUNE-UP AND PERFORMANCE MAINTENANCE

1982 EST BYPASS wire connector location. On these models, this connector must be separated prior to setting the ignition timing—see text

NOT use a timing light which requires piercing of the spark plug lead. Timing lights which have a lead that must be installed between the plug and the plug wire may be used with conventional ignition systems. On HEI ignition systems, use ONLY an inductive pickuptype timing light.

NOTE: Timing lights requiring a 12 volt

DC power source (battery) may be connected as follows: Connect the positive timing light lead to the BAT terminal of the alternator; the negative timing light lead to a good engine ground. CAUTION: Be careful not to ground the positive lead to the alternator case.

4. Locate the timing tab (metal tab marked

in graduations) which is attached to the tim ing cover. Locate the single mark on the vi bration damper (one groove). Clean both the timing tab and the damper marking. Use chalk to accentuate the marks if necessary.

5. Be sure that all wiring and tools are clear of the fan and belts. Start the engine and al low it to idle. Aim die timing light at the marks and note where the vibration damper mark aligns with die timing tab.

NOTE: The "O" marking on the tab is the

top dead center (TDC) mark and all the before top dead center (BTDC) marks are on

the "before" (advance] sice of the zero, or the "A" (advance] side of zero. Later models are marked to indicate Before and After.

6. Loosen the distributor clamp (holddown) bolt and slowly rotate the distributor as necessary until the damper mark is aligned with the specified mark of the timing tab. Tighten the hold-down bolt and recheck the timing.

7. Turn the engine off and remove the timing light.

8. If so equipped, unplug and reconnect the vacuum advance hose to the distributor.

7980 CALIFORNIA

Refer to the underhood emissions label for the proper timing adjustment procedure.

1981

Refer to the underhood emissions label for the proper timing adjustment procedure.

7982-84

The ignition timing of 1982-84 models is adjusted in basically the same manner as previously described (1963-80). The exception to this is that the EST BYPASS wire from the distributor must be disconnected prior to the timing adjustment. Trace the four wires from

Page 54

TUNE-UP AND PERFORMANCE MAINTENANCE 49

CHECK ENGINE lamp location. This lamp will be illuminated while the EST BYPASS wire is disconnected

the distributor housing which join at a common multi-connector, close to the distributor. Follow the tan wire with a black stripe (EST BYPASS wire) from the multi-connector. Past the multiconnector, the EST BYPASS wire has its own, single connector. NOTE: On 1984 models, disconnect the 4

terminal EST connector to operate in the bypass timing mode.

Separate this connector before adjusting the timing. While the EST BYPASS wire is disconnected, the CHECK ENGINE light on the instrument panel will illuminate. After adjusting the timing, reconnect the EST BYPASS connector; the CHECK ENGINE light will go out.

NOTE: It is not necessary to adjust the idle

speed on 1982—84 models prior to the timing

adjustment, though the engine must be at

normal operating temperature. 1984

models incorporate an Electronic Spark

Control (ESC) into the distributor which

retards the spark advance when engine detonation occurs. If the controller fails, the result could be no ignition, no retard or full re-

tard. Some engines will also have a magnetic

timing probe hole for use with electronic timing equipment. Consult the manufacturer's

instructions for the use of this equipment.

Valve Lash

ADJUSTMENT

Engines equipped with hydraulic lifters VERY rarely need adjustment of the valve lash. If the vehicle runs well and there is no audible "clicking" in the valvetrain, leave it alone. This is because removal of the valve covers on vehicles equipped with air conditioning, various emission controls, cruise control, etc., can be a major project in itself.

On air conditioned models, the A/C compressor must be moved out of the way to gain access to one of the valve covers. Do not disconnect the refrigerant lines to move the compressor. After the cover is removed, either move the compressor to retighten the belt or remove the belt completely so that it will not tangle while the engine is running.

On early models equipped with fuel injection, removal of the left valve cover requires removal of the air cleaner hose, air meter adaptor, and pyrometer housing.

If wiring is attached to metal clips on the valve cover, carefully bend each clip to free the wire from the valve cover. If corrugated plastic tubing containing wiring is attached to the valve cover with plastic clips, the clips can be undone by gently twisting the upper

Page 55

50 TUNE-UP AND PERFORMANCE MAINTENANCE

Adjusting the valve lash on a hydraulic lifter en

part of the clip while holding the lower section. If the clip must be removed, press the lowermost arms of the clips together with needle nose pliers and push upward.

If the vehicle uses a PCV valve pressed into the valve cover grommet, pull the valve from the grommet and remove the valve from the hose. Plug the hose with an old bolt to prevent a vacuum leak. Models having a hose running from the air cleaner to the exhaust manifold require removal of the air cleaner assembly and the hose. Plug any vacuum lines which must be disconnected.

Should it be necessary to remove additional components to gain access to the valve covers, note the wire and/or vacuum hose connection locations and sizes of the bolts which retain the components).

1. Purchase oil stopper clips for the rocker arms. These are available at most auto parts stores. These clips are installed either over (metal style) or in (plastic style) the rocker arm oiling hole located at the pushrod end of the rocker arm. If these clips are not installed, both you and your Corvette will become oil soaked when the engine is started.

2. Start the engine and allow it to reach normal operating temperature.

3. Remove the valve covers. If you have only 8 oil stopper clips, remove only one valve cover and adjust the valves. Then adjust the valves on the other side after the first cover has been reinstalled.

4. Start the engine and allow it to idle.

5. HYDRAULIC LIFTER ENGINES: Slowly loosen the rocker arm nut until the rocker arm starts to clatter. Tighten the nut

Adjusting the solid valve lifters

(clockwise) just until the clatter stops. This position is what is termed "zero lash". Slowly tighten the nut VA turn then wait about ten seconds for the idle to smooth out. Repeat this until the nut is tightened one full turn past zero lash.

CAUTION: You must wait until the engine

smooths out after each V* turn past zero

lash. Impatience in this case can cause en-

gine damage due to valve interference.

Repeat step 5 for each remaining valve. 5A.

MECHANICAL (SOLID) LIFTER ENGINES: Find your intake and exhaust valve adjusting specs in the Tune-Up chart.

Use feeler gauges the same thickness as the adjusting specs. Insert the appropriate feeler

gauge between the rocker arm and the valve.

The feeler gauge should fit with a slight drag.

If the gauge does not fit, loosen the rocker adjusting nut until it does. Tighten the adjusting nut until the gauge can be moved with

a slight pull. Repeat step 5A for each remain-

6. Remove the oil stopper clips and rein

stall the valve covers.

7. Reinstall and/or reconnect and related

items.

ing valve.

gine

idle Speed and Mixture Adjustment

Idle mixture and speed adjustments are critical aspects of exhaust emission control. It is

Page 56

TUNE-UP AND PERFORMANCE MAINTENANCE 51

HOLLEY4150

important that all tune-up instructions be carefully followed to ensure satisfactory engine performance and minimum exhaust pollution. The different combinations of emission systems application on the different engine models have resulted in a great variety of tune-up specifications. See the "TuneUp Specifications" chart at the beginning of this chapter. Beginning in 1968, all models have a decal conspicuously placed in the engine compartment giving tune-up specifications.

When adjusting a carburetor with two idle

mixture screws, adjust them alternately and evenly, unless otherwise stated.

In the following adjustment procedures the term "lean roll" means turning the mixture adjusting screws in (clockwise) from optimum setting to obtain an obvious drop in engine speed (usually 20 rpm).

NOTE: Due to the camshaft design of some

special high performance engines (350/LT.I, 427IL88,454/LS6, etc.) it is normal for these engines to have a "lopey" idle.

1963-67 WITHOUT A.I.R.

NOTE: Adjust with air cleaner removed. 1.

Connect a tachometer and vacuum

gauge to the engine, then set the parking brake and shift the manual transmission into Neutral, automatic into Drive.

2. Turn the idle mixture screw(s) in until

lightly seated, then back out IVz turns.

3. With engine running, adjust the idle

speed screw to obtain the specified rpm.

4. Adjust the idle mixture screw(s) to ob tain the highest steady manifold vacuum at the specified speed. If necessary, reset the idle speed screw while adjusting mixture.

NOTE: On air conditioned models, the air

conditioner is turned on and the hot idle compensator valve is held closed while adjusting idle speed and mixture.

5. Final adjustment should be made with

the air cleaner installed.

6. Remove tachometer and vacuum gauge.

1966-67 WITH A.I.R.

Adjust with air cleaner removed.

1. Connect a tachometer to the engine,

place manual transmission in Neutral, auto matic in Drive.

2. Turn idle mixture screw(s) in until

lightly seated, then back out 3 turns.

IDLE MfXTURE |

SCREWS SCREW

Carter WCFB idle mixture and speed adjustment screws screws

IDLE MIXTURE /"

ADJUSTING SCREWS

Carter AFB idle mixture and speed adjustment screws

IDLE SPEED /

ADJUSTING SCREW

DLE

SPEED

Holley 4150 idle mixture and speed adjustment

Rochester Quadrajet idle mixture and speed adjustment screws

ROCHESTER 4MV

Page 57

52 TUNE-UP AND PERFORMANCE MAINTENANCE

Holley 2300 idle mixture and speed adjustment

screws

3. With engine running, adjust the idle

speed screw to obtain the specified idle speed.

4. Adjust the idle mixture screw(s) in to "lean roll" position, then back them out (rich) V* turn. Readjust the idle speed screw to keep the engine at the specified idle speed while adjusting the mixture.

NOTE: On air conditioned cars, turn the

air conditioner off with 327 cu in. engines. Air conditioner must be on and hot idle compensator held closed with 427 cu in. engines.

5. Final adjustment should be made with

the air cleaner installed.

6. Remove the tachometer.

1968-69

Adjust with air cleaner installed.

1. Turn the idl e mixture screw(s) in until

lightly seated, then back out 3 turns.

2. With engine at operating temperature,

adjust idle speed screw to obtain specified rpm, manual transmissiopn in Neutral and automatic in Drive.

NOTE: On all 1968 models except 350 H.P.

327 cu. in. with manual transmission, the air conditioner is turned off. On the abovementioned vehicles the air conditioner is left on. On 1969 models, turn the air conditioner either on or off according to the instructions on the tune-up decal.

3. Adjust one idle mixture screw to obtain

the highest steady idle speed.

4. Adjust the idle speed screw to the speed

specified on the tune-up decal.

NOTE: On models equipped with an idle

solenoid, adjust the solenoid plunger hex to obtain 600 rpm. Disconnect the wire at the solenoid to deenergize it, allowing the throttle lever to contact the carburetor idle speed screw. Adjust the carburetor idle

HOLLEY 2300C (PRIMARY)

speed screw. Adjust the carburetor idle screw to obtain 400 rpm.

5. Adjust the mixture screw in to "lean roll"

position, then back out (rich) % turn.

6. Repeat Steps 3, 4, and 5 for the other

idle mixture screw.

7. Readjust the idle speed screw to obtain

final specified rpm, if necessary.

1970

Adjust with air cleaner installed.

If the vehicle is equipped with Evaporative Emission, disconnect the fuel tank line from the vapor canister while making the idle speed and mixture adjustments. Warm up the engine and leave it running while adjusting. The choke valve and, if applicable, air cleaner damper door should remain open. Leave the air conditioning off.

350 (300, 350 and 370 hp) Engines

1. Adjust the idle mixture screws equally

to obtain maximum idle speed.

2. On the 300 H.P. engine width manual transmission in Neutral adjust the idle speed screw to obtain 700 rpm. On the 300 H.P. engine with automatic transmission in Drive, adjust the idle speed screw to obtain 600 rpm.

3. On the 350 and 370 H.P. engines, ad just the idle speed screw to obtain 750 rpm with the manual transmission in Neutral.

454 (450 hp) Engine

1. Remove the air cleaner.

2. Disconnect the distributor vacuum hose

at the distributor and plug the hose.

3. Adjust the mixture screws for maximum

idle speed.

4. With manual transmission in Neutral,

adjust the carburetor idle speed screw to ob tain 750 rpm. With automatic transmission in Drive, adjust the carburetor idle speed screw to obtain 700 rpm.

5. Turn one idle mixture screw to obtain a

20 rpm drop in idle speed, then back the screw out % turn. Repeat for the second idle mixture screw.

6. Repeat Step 4 above.

7. Reconnect the distributor vacuum hose

and install the air cleaner.

454 (345 hp) and 454 (390 hp) Engines

1. Disconnect the distributor vacuum hose

at the distributor and plug the hose.

2. Turn the idle mixture screws in until

Page 58

TUNE-UP AND PERFORMANCE MAINTENANCE 53

Rochester Quadrajet

speed screw

they are lightly seated, then back them out 4 turns.

3. With automatic transmission in Drive, adjust the carburetor idle speed screw to ob tain 630 rpm. Adjust the idle mixture screws in equally to obtain 600 rpm.

4. With manual transmission in Neutral, adjust the carburetor idle speed screw to ob tain 700 rpm. Turn one of die mixture screws in until the engine speed drops 40 rpm. Readjust the idle speed screw to obtain 700 rpm. Turn in the other mixture screw until die engine speed drops 40 rpm. Readjust the idle speed screw to obtain 700 rpm.

5. Reconnect the distributor vacuum hose.

1971

Adjust with air cleaner installed.

The following initial idle adjustments are part of the normal engine tune-up. There is a tune-up decal placed conspicuously in the engine compartment outlining the specific procedure and settings for each engine application. Follow all of the instructions when adjusting the idle. These tuning procedures are necessary to obtain the delicate balance of variables for the maintenance of both reliable engine performance and efficient exhaust emission control.

NOTE: All engines except the 350 (330

hp) and 454 (425 hp) have limiter caps on the mixture-adjusting screws. The idle mixture is preset and the limiter caps installed at the factory in order to meet emission control standards. Do not remove these limiter caps unless all other possible causes of poor idle condition have been thoroughly checked out.

The solenoid used on 1971 carburetors is

different from the one used on earlier models.

IDLE MIXTURE

SOLENOID SCREW

CARBURETOR (IDLE SPEED) SCREW

Holley 4150 (with idle solenoid) idle mixture and speed adjustment locations

Combination Emission Control System (C.E.C. solenoid) valve regulates distributor vacuum as a function of transmission gear position.

CAUTION: The C.E.C. solenoid is ad-

justed only after: 1) replacement of the solenoid, 2) major carburetor overhaul, or 3) after the throttle body is removed or replaced.

All initial adjustments described below are

made:

1. With the engine warmed up and run

ning.

2. With the choke fully open.

3. With die fuel tank gas cap removed.

4. With die vacuum hose disconnected at

the distributor and plugged.

Be sure to reconnect the distributor vacuum hose and to connect the fuel tank to evaporative emission canister line or install die gas cap when idle adjustments are complete.

350 (4-BBL Quadrajet) Engines

Adjust the carburetor idle speed screw (NOT die solenoid plunger) to obtain 600 rpm (manual transmission in Neutral widi the air

IDLE SPEED (SOLENOID) SCREW

(with idle solenoid) idle

IDLE MIXTURE SCREWS

Rochester Quadrajet (with idle solenoid) idle mixture screws

Page 59

54 TUNE-UP AND PERFORMANCE MAINTENANCE

conditioner off) or 550 rpm (automatic transmission in Drive with the air conditioner on).

350 and 454 (4-BBL Holley) Engines

1. Adjust the carburetor idle speed screw (NOT the solenoid plunger) to obtain 700 rpm (manual transmission in Neutral or automatic transmission in Drive).

2. Adjust the idle mixture screws alter nately to obtain the maximum smooth idle speed.

3. Adjust one of the idle mixture screws to obtain a 20 rpm drop ("lean roll"), then back it out %, turn.

4. Repeat Step 4 above for the other idle mixture screw.

5. Readjust the carburetor idle speed screw to obtain 700 rpm if necessary.

454 (4-BBL Quadrajet) Engines

Turn the air conditioner off. Adjust the carburetor idle speed screw (NOT the solenoid plunger) to obtain 600 rpm (manual transmission in Neutral or automatic transmission in Drive).

1972

NOTE: All carburetors are equipped with idle limiter caps and idle mixture is preset at the factory and should not require adjustment.

1. Remove the fuel filler cap but do not

remove the vapor line.

2. Detach the distributor va cuum hose and

plug the hose.

3. Set the parking brake and turn the air conditioner (if so equipped) off. On cars equipped with an automatic transmission, check the wheels.

4. Allow the engine to reach normal oper ating temperature. Be sure that the choke is open.

5. If the car has an automatic transmis sion, set the selector in Drive. If the car has a manual transmission keep die transmission in Neutral.

6. Adjust the anti-dieseling solenoid to the higher of the two rpm figures given in the specifications.

CAUTION: Do not turn the solenoid more

than one complete turn unless the electrical lead is disconnected (solenoid deenergized).

7. Disconnect the solenoid lead and set the idle speed to the lower of the two figures given in the specifications. Use the normal idle speed adjusting screw.

NOTE: If no lower figure is given, adjust

the idle to 450 rpm.

8. Reconnect all of the wires and hoses

which were disconnected in order to perform these adjustments.

1973

Ah1 models are equipped with idle limiter caps and idle solenoids. Disconnect the fuel tank line from die evaporative canister. The engine must be running at operating temperature, choke off, parking brake on, and rear wheels blocked. Disconnect the distributor vacuum hose and plug it. After adjustment, reconnect the vacuum and evaporative hoses.

Four-barrel 350 and 454 cu in. V8s

1. Adjust the idle stop solenoid screw for

900 rpm on manual, 600 rpm on automatic.

2. Connect the distributor vacuum hose and position the fast idle cam follower on the top step of the fast idle cam (turn air condi tioning off) and adjust die fast idle to 1300 rpm on manual transmission 350 engines; 1600 on manual 454 engines and all automat ics (in Park).

Optional 350 cu in. (L82) V8

1. Adjust the idle stop solenoid screw (air conditioning off) for a speed of 900 rpm on manual transmission; 700 rpm on automatic (in Drive).

2. Connect the distributor vacuum hose and position the fast idle cam follower on the top step of the cam (turn air conditioning off) and adjust the fast idle to 1300 rpm on man ual; 1600 rpm on automatic.

1974

The same preconditions as for 1973 apply.

Four-barrel 350 cu in. V8

1. Turn the air conditioning off. Adjust the idle stop solenoid screw for 900 rpm on man ual transmission models; 600 rpm on auto matic (in Drive).

2. Connect the distributor vacuum hose. Position the fast idle cam follower on the top step of the fast idle cam and adjust the fast idle speed to 1300 rpm on manual; 1600 on automatic (in Park).

Optional 350 cu in. (L82) V8

1. Turn the air conditioning off. Adjust the idle stop solenoid for 900 rpm on manual; 700 rpm on automatic (in Drive).

2. Connect the distributor vacuum hose.

Page 60

TUNE-UP AND PERFORMANCE MAINTENANCE 55

TURN IDLE SPEED SCREW TO

SPECIFICATIONS

A/C OFF

IDLE SPEED ADJUSTMENT

WITHOUT SOLE

NOID

y SOLENOID ENERGIZED

DRIVE.

M/T IN NEUTRAL

PREPARE VEHICLE FOR ADJUSTMENTS

LEAD AFTER ADJ

USTMENT!

ELECTRICAL

I/ TURN IDLE SPEED SCREW TO

SPECIFICATIONS

A/CO*F

5OLENOI

A/C IDLE SPEED ADJUSTMENT

WITH SOLENOID

Position the fast idle cam follower on the top step of the cam and adjust the fast idle to 1300 rpm on manual; 1600 rpm on automatic (in Park).

454 cu in. V8

1. Shut off the air conditioning. Adjust the idle stop solenoid screw for 800 rpm on man ual; 600 rpm on automatic (in Drive).

2. Connect the distributor vaccuum hose and position the fast idle cam follower on the top step of the cam and adjust the fast idle to 1600 rpm on manual; 1500 rpm on automatic (in Park).

1975-76

The same preconditions as for 1973 apply.

1. Turn the air conditioning off.

2. Disconnect the idle speed solenoid. Turn the idle speed screw to adjust for the lower of the two idle speeds specified on the underhood tune-up decal. Adjust automatic transmission cars in Drive with wheels blocked; manual transmission cars in Neu tral.

3. Connect the idle speed solenoid. Open the throttle to extend the solenoid plunger.

4. Use the solenoid plunger to adjust the idle speed to the higher of the two speeds on the underhood tune-up decal.

1977-IDLE SPEED

Run the engine to normal operating temperature, A/C off, vacuum advance line disconnected and plugged, FUEL TANK line at the canister disconnected. Place the manual transmission in neutral; automatic transmission in drive. Connect a tachometer to the engine.

NOTE: Make sure the parking brake is on

and the drive wheels are sufficiently blocked when placing the transmission in drive.

5. Turn the solenoid screw to higher of the two idle speeds specified on the underhood tune-up decal.

6. Reconnect the A/C compressor lead.

1977-IDLE MIXTURE

NOTE: Idle mixture screws have been preset at the factory and capped and should not require adjustment, however if the need arises follow the procedure listed below.

1. Set the parking brake and block the

drive wheels.

2. Remove the air cleaner to gain access to the carburetor, but keep the vacuum hoses connected.

3. Run the engine to normal operating temperature with the choke open.

4. Turn the A/C off.

5. Disconnect and plug the vacuum ad vance hose at the distributor.

6. Check the ignition timing and adjust as necessary.

7. Using a sharp knife, carefully remove the plastic caps from the idle mixture screws. Use extreme caution to avoid bending the mixture screws.

8. Lightly seat the screws then back out equally just enough so the engine will run.

9. Place the automatic transmission in drive or the manual transmission in neutral.

10. Back out each screw (richen) % turn at

/PREPARE VEHICLE FOR ADJUSTMENTS

SET CURB IDLE SPEED TO

Without A/C

1. Turn the idle speed screw to achieve the

rpm specified on the underhood tune-up decal.

With A/C

1. Turn the idle speed screw to the lower of the two idle speeds specified on the under hood tune-up decal.

2. Turn the A/C system on.

3. Disconnect the A/C compressor lead at the compressor.

4. Open the throttle slightly to allow the solenoid plunger to fully extend.

A/C COMPRESSOR LEAD DISCONNECTED AT A/C COMPRESSOR. A/C ON. A/T TRANSMISSION IN

TURN SOLENOID SCREW TO ADJUST TO SPECIREO RPM (RECONNECT A/C COMPRESSOR

©OPEN THRI

1ROTTLE 5UGHTLT TO ALLOW (<? ^X

no PLUNGER TO FULIV EXTEND v—

Idle speed adjustment (1977-80 M4MC)

SET CURB IDLE SPEED TO

Page 61

56 TUNE-UP AND PERFORMANCE MAINTENANCE

a time until the maximum idle speed is obtained. Then set the idle speed screw to: Standard engine (180 hp) M.T.-800 rpm, A.T.-550 rpm; Optional engine (210 hp) M.T.900 rpm, A.T. (low altitude) 750 rpm, A.T. (high altitude) 650 rpm.

11. Turn in each screw (lean) Vs turn at a time until the idle reaches the following rpm: Standard engine (180 hp)-M.T. -700 rpm, A.T.-500 rpm. Optional engine (210 hp)-800 rpm, A.T. (low altitude), 600 rpm for A.T., high altitude.

12. Reset the idle speed to specification.

13. Reconnect the vacuum hoses and in stall the air cleaner.

1978-80 IDLE SPEED

This procedure applies only to those models which DO NOT have the computer controlled emissions system. Vehicles having the computer system have 13 screws retaining the air horn of the carburetor; vehicles without the computer system have 9 screws retaining the carburetor air horn. Also, computer equipped vehicles do not have the familiar vacuum advance unit installed on the distributor, as the spark advance is controlled by the computer.

CAUTION: // your vehicle has the com-

puter emissions system, DO NOT attempt to adjust either the idle speed or mixture, as the fuel system calibration could become severely upset.

Run the engine to normal operating temperature, A/C off, die purge hose at die vapor canister and the vacuum hose at the EGR valve disconnected and plugged. Place the manual transmission is Neutral and the automatic transmission in Drive. NOTE: Make

sure the parking brake is on and the drive wheels are safely blocked before the transmission is placed in Drive.

Without A/C

1. Turn the idle speed screw to achieve the

rpm specified on the underhood specifications decal.

With A/C

1. Turn the idle speed screw to the lower of the two idle speeds listed on the under hood specifications decal.

2. Turn the air conditioning on.

3. Disconnect the A/C compressor lead at the compressor (two-wire connector).

4. Open the throttle slightly to allow the solenoid plunger to extend fully.

5. Turn the solenoid screw to adjust the engine speed to the higher of the two speeds listed on the specifications decal under the hood. Use the higher idle speed, NOT the fast idle speed specification.

6. Reconnect the A/C compressor lead.

1978-80 IDLE MIXTURE

Changes in the idle systems of these models make it impossible to properly adjust the mixture without the use of a propane enrichment system, not available to the general public.

In some 1978 and all 1979-80 models, the idle mixture screws are sealed within the dirotde body of the carburetor. Idle mixture adjustments should be left to the professional technician with the proper equipment and experience.

1981-84 IDLE MIXTURE

Idle speed and mixture are controlled strictly by the computer emissions system. Do not attempt to adjust the idle speed or mixture as these functions are controlled by the computer.

NOTE: For all throttle body injection ad-

justments, see the Fuel Injection section.

Page 62

Engine Rebuilding

UNDERSTANDING THE ENGINE ELECTRICAL SYSTEM

The engine electrical system can be broken down into three separate and distinct systems—(1) the starting system; (2) the charging system; (3) the ignition system.

NOTE: See "Troubleshooting" for typical

diagnosis procedures.

Battery and Starting System

The battery is the first link in the chain of mechanisms which work together to provide cranking of the automobile engine. In most modern cars, the battery is a lead-acid electrochemical device consisting of six two-volt (2 V) subsections connected in series so the unit is capable of producing approximately 12 V of electrical pressure. Each subsection, or cell, consists of a series of positive and negative plates held a short distance apart in a solution of sulfuric acid and water. The two types of plates are of dissimilar metals. This causes a chemical reaction to be set up, and it is this reaction which produces current flow from the battery when its positive and negative terminals are connected to an electrical appliance such as a lamp or motor. The continued transfer of electrons would eventually convert the sulfuric acid in the electrolyte to water, and make the two plates identical in chemical composition. As electrical energy is removed from the battery, its voltage output tends to drop. Thus, measuring battery voltage and battery electrolyte composition are two ways of checking the ability of the unit to supply power. During the starting of the engine, electrical energy is removed from the battery. However, if the charging circuit is in

Engine and

good condition and the operating conditions are normal, the power removed from the battery will be replaced by the generator (or alternator) which will force electrons back through the battery, reversing the normal flow, and restoring the battery to its original chemical state.

The battery and starting motor are linked by very heavy electrical cables designed to minimize resistance to the flow of current. Generally, the major power supply cable that leaves the battery goes directly to the starter, while other electrical system needs are supplied by a smaller cable. During the starter operation, power flows from the battery to the starter and is grounded through the car's frame and the battery's negative ground strap.

The starting motor is a specially designed, direct current electric motor capable of producing a very great amount of power for its size. One thing that allows the motor to produce a great deal of power is its tremendous rotating speed. It drives the engine through a tiny pinion gear (attached to the starter's armature), which drives the very large flywheel ring gear at a greatly reduced speed. Another factor allowing it to produce so much power is that only intermittent operation is required of it. Thus, little allowance for air circulation is required, and the windings can be built into a very small space.

Hie starter solenoid is a magnetic device which employs the small current supplied by the starting switch circuit of the ignition switch. This magnetic action moves a plunger which mechanically engages the starter and electrically closes the heavy switch which connects it to the battery. The starting switch circuit consists of the starting switch contained within the ignition switch, a transmission neutral safety switch or clutch pedal

Page 63

58 ENGINE AND ENGINE REBUILDING

switch, and the wiring necessary to connect these with the starter solenoid or relay.

A pinion, which is a small gear, is mounted to a one-way drive clutch. This clutch is splined to the starter armature shaft. When the ignition switch is moved to the "start" position, the solenoid plunger slides the pinion toward the flywheel ring gear via a collar and spring. If the teeth on the pinion and flywheel match properly, the pinion will engage the flywheel immediately. If the gear teeth butt one another, the spring will be compressed and will force the gears to mesh as soon as the starter turns far enough to allow them to do so. As the solenoid plunger reaches the end of its travel, it closes the contacts that connect the battery and starter and then the engine is cranked.

As soon as the engine starts, the flywheel ring gear begins turning fast enough to drive the pinion at an extremely high rate of speed. At mis point, the one-way clutch begins allowing the pinion to spin fester than the starter shaft so that the starter will not operate at excessive speed. When the ignition switch is released from the starter position, the solenoid is de-energized, and a spring contained within the solenoid assembly pulls the gear out of mesh and interrupts the current flow to the starter.

The Charging System

The automobile charging system provides electrical power for operation of the vehicle's ignition and starting systems and all the electrical accessories. The battery serves as an electrical surge or storage tank, storing (in chemical form) the energy originally produced by the engine-driven generator. The system also provides a means of regulating generator output to protect the battery from being overcharged and to avoid excessive voltage to the accessories.

The storage battery is a chemical device incorporating parallel lead plates in a tank containing a sulfuric acid-water solution. Adjacent plates are slightly dissimilar, and the chemical reaction of the two dissimilar plates produces electrical energy when the battery is connected to a load such as the starter motor. The chemical reaction is reversible, so that when the generator is producing a voltage (electrical pressure) greater than that produced by the battery, electricity is forced into the battery, and the battery is returned to its fully charged state.

The vehicle's generator is driven mechanically, through V belts, by the engine crankshaft. It consists of two coils of fine wire, one stationary (the "stator"), and one movable (the ''rotor"). The rotor may also be known as the "armature," and consists of fine wire wrapped around an iron core which is mounted on a shaft. The electricity which flows through the two coils of wire (provided initially by the battery in some cases) creates an intense magnetic field around both rotor and stator, and the interaction between the two fields creates voltage, allowing the generator to power the accessories and charge the battery.

There are two types of generators; the earlier is the direct current (DC) type. The current produced by the DC generator is generated in the armature and carried off the spinning armature by stationary brushes contacting the commutator. The commutator is a series of smooth metal contact plates on the end of the armature. The commutator plates, which are separated from one another by a very short gap, are connected to die armature circuits so that current will flow in one direction only in the wires carrying the generator output. The generator stator consists of two stationary coils of wire which draw some of the output current of the generator to form a powerful magnetic field and create the interaction of fields which generates the voltage. The generator field is wired in series with the regulator.

Newer automobiles use alternating current generators or "alternators" because they are more efficient, can be rotated at higher speeds, and have fewer brush problems. In an alternator, the field rotates while all the current produced passes only through the stator windings. The brushes bear against continuous slip rings rather than a commutator. This causes the current produced to periodically reverse the direction of its flow. Diodes (electrical one-way switches) block the flow of current from traveling in the wrong direction. A series of diodes is wired together to permit the alternating flow of the stator to be converted to a pulsating, but unidirectional flow at the alternator output. The alternator's field is wired in series with the voltage regulator.

The regulator consists of several circuits. Each circuit has a core, or magnetic coil of wire, which operates a switch. Each switch is connected to ground through one or more resistors. The coil of wire responds directly to system voltage. When the voltage reaches the

Page 64

ENGINE AND ENGINE REBUILDING 59

required level, the magnetic field created by the winding of wire closes the switch and inserts a resistance into the generator field circuit, thus reducing the output. The contacts of the switch cycle open and close many times each second to precisely control voltage.

While alternators are self-limiting as far as maximum current is concerned, DC generators employ a current regulating circuit which responds directly to the total amount of current flowing through the generator circuit rather than to the output voltage. The current regulator is similar to the voltage regulator except that all system current must flow through the energizing coil on its way to the various accessories.

SAFETY PRECAUTIONS

Observing these precautions will ensure safe handling of the electrical system components, and will avoid damage to the vehicle's electrical system:

1. Observing these precautions will en sure safe handling of the electrical system components, and will avoid damage to the vehicle's electrical system:

2. Be absolutely sure of the polarity of a booster battery before making connections. Connect the cables positive to positive, and negative to negative. Connect positive cables first and then make the last connection to a ground on the body of the booster vehicle so that arcing cannot ignite hydrogen gas that may have accumulated near the battery. Even momentary connection of a booster battery with the polarity reserved will damage alter nator diodes.

3. Disconnect both vehicle battery ca bles before attempting to charge a battery.

4. Never ground the alternator or gener ator output or battery terminal. Be cautious when using metal tools around a battery to avoid creating a short circuit between the terminals.

5. Never ground the field circuit be tween the alternator and regulator.

6. Never run an alternator or generator without load unless the field circuit is discon nected.

7. Never attempt to polarize an alterna tor.

8. Keep the regulator cover in place when taking voltage and current limiter readings.

9. Use insulated tools when adjusting the regulator.

10. Whenever DC generator-to-regulator

wires have been disconnected, the generator

must be repolarized. To do this with an externally grounded, light duty generator, momentarily place a jumper wire between the battery terminal and the generator terminal of the regulator. With an internally grounded heavy duty unit, disconnect the wire to the regulator field terminal and touch the regulator battery terminal with it.

11. Never disconnect components with the

ignition ON.

The Conventional Ignition System

MECHANICAL OPERATION

The distributor is geared to the camshaft of the engine, and in the case of a Chevrolet V8, is also used to drive the engine oil pump in addition to its usual "spark sorting" duties. As the distributor shaft turns, the lobes of the distributor cam actuate the breaker point set, causing the points to open and close. The points are attached to the breaker plate, which on models using a vacuum advance system, is capable of rotating around the distributor shaft a small amount. This rotation of the breaker plate changes the relationship between the distributor shaft and the point set. The change in this relationship alters the time at which the points open, thereby changing the ignition timing. The amount of the ignition timing change, in degrees, is controlled by the vacuum advance diaphragm which senses the engine load through engine vacuum changes. The vacuum advance diaphragm is controlled by either "ported" or "manifold" vacuum. A ported vacuum source is one that is located above the throttle plates of the carburetor, whereas a manifold vacuum source is located below the carburetor throttle pktes (or attached to a fitting directly on the intake manifold). At a given open throttle position, the vacuum signal to the distributor will be basically the same, whether it is from a ported or manifold vacuum source. During idle, however, manifold vacuum is high; ported is low. As vacuum to the advance unit is increased, the amount of degrees which the unit moves (advances) the breaker plate is also increased, and vice-versa (retard). It is because of this that you must disconnect the vacuum advance unit before adjusting the initial timing on engines which have a manifold vacuum source to the distributor. The most important function of the vacuum advance is to advance the ignition timing during cruise conditions for improved fuel

Page 65

60 ENGINE AND ENGINE REBUILDING

economy. As engine load increases, engine vacuum drops, which allows the ignition timing to retard, thereby preventing detonation due to over-advanced timing. Some special high performance models such as the 427/L88 do not have vacuum advance systems. Fuel economy was not designed into such "offroad" engines.

NOTE: Do not remove the vacuum ad-

vance for street usage—fuel economy will suffer, along with engine performance if not set-up properly.

Another timing feature of the distributor is the centrifugal advance mechanism. This mechanism alters the ignition timing by rotating the distributor cam (a small amount) independent of the distributor shaft. Again, the relationship between the distributor shaft and the point opening is changed due to this rotation. The centrifugal advance mechanism consists basically of two small springs and two specially shaped weights attached to both the distributor cam and the shaft. These components are mounted underneath the ignition rotor. Instead of vacuum, this mechanism uses engine rpm as a guide for advancing the ignition timing. As engine rpm (and distributor shaft rpm) increases, the weights are moved gradually outward (against the spring tension) by centrifugal force. As the weights move outward, the distributor cam is moved to a more advanced timing position. When the engine rpm drops, the springs gradually pull the weights back to their low-speed position, thereby reducing the amount of tuning advance.

ELECTRICAL OPERATION

The point set, or breaker points as they are sometimes called, is the switching device of a conventional ignition system. The "primary" side of the ignition coil is connected to the battery, through the ignition switch, a resistor, and various wiring. When the ignition switch is in the "run" position, voltage from the ignition switch passes through a resistor, which lowers the battery voltage to the coil from 12V down to about 6-8V.

NOTE: If this resistor is defective, the full

12V from the battery will quickly burn the breaker point contacts and shorten the life of the ignition coil.

When the ignition switch is in the "start"

position, the resistor is bypassed. This provides a full 12V to the ignition system to aid

in starting the engine. Voltage flow after

the resistor (or bypass

wire) is through the primary (low voltage) windings of the coil, to the breaker point set. When the points are closed (grounded), a magnetic field is produced within the primary windings of the ignition coil. When the points open, the coil voltage no longer has an easy path to ground. The magnetic field collapses and transfers the voltage from the primary windings (outer) of the coil to the "secondary" windings (inner) of the coil, through induction. Since the number of secondary windings in the ignition coil is much greater than the primary, the voltage is multiplied to roughly 20-25,000 volts. This high voltage then travels out of the center tower of the ignition coil, through the high tension lead (secondary coil wire) to the center tower of the distributor cap. The voltage is then distributed by the ignition rotor to the outer terminals of the distributor cap (in the "firing order"), through the plug wires and finally, the voltage jumps the gap of the spark plug, causing ignition of the air/fuel mixture in the cylinder.

The condenser, which is also attached to the breaker plate (grounded), acts as a temporary voltage storage unit when the points are closed. This helps to prevent arcing between the point contacts when the points are opened. Rapid metal transfer between the point contacts is indicative of a bad condensor.

The Breakerless Ignition Systems (Including H.E.I.)

Both the transistorized and H.E.I, systems operate in basically the same manner as the conventional ignition system, with the exception of the type of "switching device" used. As stated previously, the switching device of a conventional ignition system is the breaker point set. In the breakerless ignition systems, a toothed iron timer core is mounted on the distributor shaft. The timer core is mounted on the distributor shaft. The timer core rotates inside of an electronic pole piece. The pole piece has internal teeth (corresponding to those on the timer core) and contains a permanent magnet and pick-up coil (not to be confused with the ignition coil). The pole piece senses the magnetic field of the timer core teeth and sends a signal to the ignition module which electronically "calls the shots" concerning control of the primary coil voltage. The ignition coil operates in basically the same manner as a conventional ig-

Page 66

ENGINE AND ENGINE REBUILDING 61

nition coil (though the ignition coils DO NOT interchange), but is controlled by the timer core, pole piece, and module; instead of the breaker points and condenser.

NOTE: H.E.I, ignitions use a condensor,

but it is primarily used for radio interference purposes.

As far as the mechanical advance is concerned, the operation is also basically the same as a conventional ignition system, with the exception that the timer core rotates on the distributor shaft instead of the distributor cam used in conventional systems. The vacuum advance unit moves the breaker plate in the same manner as the conventional system, but the timing changes according to the position of the pole piece instead of the breaker points.

Appearance wise, the transistorized igni-

tion distributor looks very much like a conventional distributor, with the exception of a

two-wire lead (with a quick-disconnect plug)

coming from the dsitributor. Also, the tran-

sistorized system uses both an externally

mounted ignition coil and an ignition ampli-

fier unit which is finned for heat dissipation.

CAUTION: Do not use a conventional ig-

nition coil in place of an electronic ignition

coil, or vice-versa. Component damage

could result.

The H.E.I, distributor looks nothing like a conventional distributor. The components of an H.E.I, distributor are all contained within the distributor (pole piece, ignition coil, module, etc.).

Refer to Chapter 11 for detailed H.E.I, system troubleshooting. None of the electri cal components used in either the transistor ized or H.E.I, systems are adjustable. If a component is found to be defective, it must be replaced.

HE/ SYSTEM PRECAUTIONS

Before going on to troubleshooting, it might be a good idea to take note of the following precautions:

Timing Light Use

Inductive pick-up timing lights are the best kind to use if your car is equipped with HEI. Timing lights which connect between the spark plug and the spark plug wire occasionally (not always) give false readings.

Spark Plug Wires

The plug wires used with H.E.I, systems are of a different construction than conventional

wires. When replacing them, make sure you get the correct wires, since conventional wires won't carry the voltage. Also, handle them carefully to avoid cracking or splitting them and never pierce them.

Tachometer Use

Not all tachometers will operate or indicate correctly when used on a H.E.I, system. While some tachometers may give a reading, this does not necessarily mean the reading is correct. In addition, some tachometers hook up differently from others. If you can't figure out whether or not your tachometer will work on your car, check with the tachometer manufacturer. Dwell readings, of course, have no significance at all.

H.E.I. System Testers

Instruments designed specifically for testing H.E.I, systems are available from several tool manufacturers. Some of these will even test the module itself. However, the tests given in the following section will require only an ohmmeter and a voltmeter.

ENGINE ELECTRICAL Distributor

REMOVAL

Conventional and Transistorized Systems

1. Rotate the engine until the timing mark on the crankshaft balancer is aligned with the top dead center mark (TDC or "0") on the timing tab scale. Remove the air cleaner as sembly.

2. Remove the ignition shielding and dis connect the secondary (high tension) coil wire.

3. Release the distributor cap hold-down screws (push down and turn counterclock wise). Raise the distributor cap off of the dis tributor and check that the firing tip of the rotor is pointed at the #1 terminal of the dis tributor cap. If it is not; turn the engine one full revolution and again align the timing marks as previously stated. Recheck the rotor position.

4. Pull the plug wires out of the locating looms (if so equipped) and move the cap out of the way. Leave the plug wires attached to the cap.

5. Disconnect the battery cables at the battery.

6. Disconnect the tachometer and fuel

Page 67

62 ENGINE AND ENGINE REBUILDING

CAP ROTOR

ASSEMBLY

HOUSING

TANGED WASHER

DRIVE GEAR

DRIVE PIN

RADIO FREQUENCY

INTERFERENCE

SHIELD

WEIGHT SPRINGS

MAINSHAFT

ADVANCE WEIGHTS

CAM WEIGHT BASE

CONDENSER

CONTACT

POINT

ASSEMBLY RETAINING RING

BREAKER PLATE

VACUUM ADVANCE UNIT

0----------------------

FELT WASHER

PLASTIC SEAL

SHIM WASHER

Exploded view of the V8 points-type

injection drive cables from the distributor, if so equipped.

7. Disconnect the vacuum line from the distributor vacuum advance unit, if so equipped.

8. Mark the relationships between the following items:

a. Rotor firing tip and distributor body b. distributor body and either the fire

wall or the intake manifold

The combination of these marks will assure that the distributor gear is properly meshed with the camshaft and the ignition timing will be close enough to start the engine after the distributor is reinstalled.

9. On conventional ignitions, disconnect the distributor lead from the negative (—) terminal of the ignition coil. On transistor ized systems, carefully release and pull apart the quick-disconnect of the two-wire distrib utor lead.

10. Remove the distributor hold-down bolt

and plate.

11. Carefully pull the distributor from the engine. Note the rotation of the rotor as the distributor is pulled upward, caused by the angled distributor drive teeth.

distributor

CAUTION: Do not

rotate the engine while the distributor is removed.

12. Service the distributor as necessary.

H.E.I. Systems

1. Rotate the engine until the timing mark on the balancer is aligned with the top dead center mark (TDC or "O") on the timing tab scale.

2. Remove the air cleaner assembly and the ignition shielding.

3. With the ignition switch OFF, discon nect the feed, module, and tachometer wir ing from the drivers side of the distributor cap. Do so by releasing the connector retain ing tabs and pulling downward on the con nectors. On 1981—84 models, also disconnect the four-wire connector installed in the wir ing from the opposite side of the distributor.

CAUTION: Never allow the "Tach" termi-

nal to touch ground.

4. Locate the locking tabs of the spark plug wire retaining ring (on the distributor cap). Move each of the two locking tabs outward to release the retaining ring. With the plug wires still attached to the ring, carefully remove the retaining ring from the distributor cap. Pull

Page 68

NOTE: The following specifications

testing.

Year

1963-64

1965

1966

1967-68

All except fuel injection

Model

Fuel injection Base engine Special performance Fuel injection Base engine Special performance

w/transistor ign F.I. w/transistor ign 300 hp 350 hp 390 hp 350 hp w/transistor ign 390 hp w/transistor ign 425 hp 300 hp

350 hp 390 hp, 400 hp 435 hp

430 hp L88 350 hp w/transistor ign 390 hp, 400 hp

Distributor Specifications

are given in degrees advance at crankshaft speed. Half degrees for distributor machine

Distributor

Part Number

1111024 1111022 1111076 1111069

1111070 1111087

1111060

1111064 1111194 1111438 1111293

1111441 1111294 1111170 1111194 1111438

1111293 1111296 1111295

1111441

1111294

Start

Degrees

@rpm

0@700 0@700 0@750 0@800 0@800 0@750 0@800

0@800 0@900 0@950 0@900 0@900 0@900 0@900 0@900 0@950 0@900 0@900

0@1200

0 @ 900 0@900

Centrifugal Advance

Intermediate

Degrees

@rpm

11 @1600

11 @700

15 @ 1500

NA NA

15 @ 1500

NA NA

15 @ 1500 20 @ 1800

8 @ 1250

1 6.5 @ 1400

17 @ 2000 17 @ 2000 15 @ 1500 20 @ 1800 17 @ 2000

18 @ 1900

1 6.5 @ 1400

17 @ 2000

End

Degrees

@rpm

24 @ 4600

24 @ 4600 26 @ 4100 24 @ 2350 24 @ 2350 30 @ 5100 26 @ 2500

26 @ 2500 30 @ 5100 30 @ 4700 32 @ 5000 30 @ 4400 32 @ 5000 32 @ 5000 30 @ 51 00 30 @ 4700 32 @ 5000 30 @ 3800 30 @ 5000 30 @ 4400 32 @ 5000

0@8

0@4

0@6

0@8

0@7

0@8

0@7 0@7 0@6 0@8 0@7 0@8 — — 0@8 0@7

Start

Degrees @

In. Hg

0@8

Vacuum Advance

Degrees @ in. Hg

1 6.5 @ 8.2

1 6.5 @ 8.2 1 6.5 @ 8.2

1 6.5 @ 8.2

15@12

End

15 @ 15.5 15 @ 15.5

1 6.5 @ 8.2

15 @ 15.5

12@12

15 @ 15.5

12@12 12@12 15@12

15 @ 15.5

12@12

15 @ 15.5

12@12

z rn > z

m z rn

m c

Page 69

NOTE:

The following specifications

testing.

Year Model

1969

1970

1971

1972

1973

300 hp 1111490 350 hp 1111493 390 hp, 400 hp 1111926 435 hp 1111928 430 hp L88 1111927 300 hp 1111490 350 hp 1111493 370 hp 1111491 390 hp 1111464 460 hp 1112026 270 hp 1112050 330 hp 1112038 365 hp 1112051 425 hp w/manual trans 1112076 425 hp w/auto trans 1112053 200 hp 1112050 255 hp 1112101 270 hp 1112051

190 hp 1112098

250 hp 1112150

Distributor Specifications (cont.)

are given in degrees advance at crankshaft speed. Half degrees for distributor machine

Distributor

Part Number

Start

Degrees

@rpm

0@900 15 @ 1500

0@1000 10 @ 1700

0@900 17 @ 2000 0@900 2 @ 1100

0@1200 16 @ 1900

0@900 15 @ 1500 0@1150 10 @ 1700 0@1000 0@1085 17 @ 21 00 0@1000

0@1335 11 @2400 0@1330 16 @ 2250 0@1145 14 @ 2000 0@1300 25 @ 2350 0@1310 21 @ 2350 0@1335 11 @2400 0@1200 14 @ 2000 0@1145 14 @ 2000 0@1100 0@1200

Centrifugal Advance

Intermediate

Degrees

@rpm

— —

End

Degrees

@rpm

30 @ 51 00 26 @ 5000 26 @ 3800 30 @ 3800 29 @ 5000 30 @ 5100 26 @ 5000 26 @ 5000 22 @ 3200 21 @ 2300

18 @ 4200 24 @ 5000 22 @ 3000 31 @ 6000 28 @ 5000

18 @ 4200 28 @ 5000 22 @ 3000

14 @ 4200 20 @ 5000

Vacuum Advance

Start

Degrees @

in. Hg

0@8 0@7 0@7 0@8

— — 0@8 0@8 0@8 0@7 0@7 0@8 0@8 0@8 0@7 0@7 0@8 0@8 0@8 0@6 0@6

End Degrees @ in. Hg

19@17 15@12 12@12

15 @ 15.5

19@17 19@17

15 @ 15.5

12@12

12@12 15 @ 15.5 15 @ 15.5

20@17

12@12

12@12 15 @ 15.5 15 @ 15.5

20@17

15@14

15@12

m D

z m

c g

z D

Page 70

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ENGINE AND ENGINE REBUILDING 65

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Page 71

66 ENGINE AND ENGINE REBUILDING

ADVANCE

• POLE PIECE

ROTOR

CENTRIFUGAL

ROTATING

DRIVE ^St> A GEAR - 4® ^

Exploded view of the transistorized distributor

the plug wires out of the locating looms (if so equipped) and move the ring (with the wires still attached) out of the way.

5. Release the distributor cap hold-down screws (push downward and turn counterclockwise) and lift the cap assembly off of the distributor. Check that the firing tip of the rotor is pointed at the #1 terminal of the distributor cap; if it is not, rotate the engine one

full revolution and again align the timing marks. Recheck the position of the rotor.

6. Disconnect the vacuum line from the distributor vacuum advance unit, if so equipped.

7. Follow steps 5, 7, 8, and 10-12 of the previous procedure, in that order to com plete distributor removal.

INSTALLATION—ENGINE NOT DISTURBED

1. Clean the distributor and intake man ifold mating surfaces and check the condition of the cork gasket. Replace the gasket if it is damaged.

2. Position the distributor in the engine without yet engaging it. Align the distributor housing-to-engine alignment marks which were made during removal. Position the ro tor firing tip slightly counterclockwise of the corresponding distributor housing mark; re member, the rotor will turn slightly during installation.

3. Engage the distributor to the engine by moving it downward. The rotor should turn to its proper alignment position. If it does not, lift the distributor enough to disengage the drive gear, reposition the rotor and lower the distributor.

4. Install the distributor hold-down plate and just snug down the bolt.

5. Make sure that the rotor retaining screws are tight and install the distributor cap.

6. Connect the cables (tach, injection—if so equipped), wires, and vacuum line (if so equipped) to the distributor.

7. On conventional ignitions, reconnect the primary distributor lead to the coil. On models without H.E.I., reconnect the sec ondary coil wire.

8. On H.E.I, models, install the plug wire retaining ring. Press the ring downward until the two locking tabs engage. Make sure dial the plug wire terminals are firmly seated on the distributor cap terminals.

9. Reposition the plug wires into their lo cating looms, if so equipped.

10. Install the air cleaner and reconnect the

battery cables.

11. Adjust the ignition timing as previ ously outlined and tighten the distributor hold-down bolt. Reinstall the ignition shield ing as necessary.

INSTALLATION—ENGINE DISTURBED

1. The piston of the #1 cylinder must be

on its compression stroke and at the top of its

Page 72

CIRCLIP

COVER

POLE PIECE

LEAD WIRE

AMPLIFIER MODULE

CAPACITOR

VACUUM CONTROL UNIT

HOUSING

ADVANCE SPRING

GASKET

CONNECTOR

GEAR'

ENGINE AND ENGINE REBUILDING 67

Exploded view of the HEI distributor. Engines with the computer emissions system do not have the vacuum advance unit.

travel (top dead center -TDC) in order to time the ignition system to the engine. There are several ways to determine when the piston is on its compression stroke. In any case, the #1 spark plug must be removed. The various methods are as follows:

a. Hold your finger over the spark plug hole and have an assistant turn the engine over slowly. When you feel compression, watch the timing marks. Stop turning the engine over as soon as the timing mark on the crankshaft balancer is aligned with the "0" mark on the timing tab scale.

b. Insert a rag into the spark plug hole (NOT into the cylinder). Turn the engine over slowly until the rag is blown out of the hole. Stop cranking the engine when this happens and check the riming marks. If necessary, "tap" the ignition key until the timing mark on the crankshaft balancer is aligned with the "O" mark on the timing tab scale.

c. Attach a compression gauge to the spark plug hole (preferably the screw-in type; eliminating the need for an assistant). Position the gauge dial so that it may be viewed while cranking the engine. Turn the engine over until the gauge needle reading

WASHER

increases, indicating compression. Stop cranking the engine when this happens and check the timing marks. If necessary, "tap" the ignition key until the timing mark on the crankshaft balancer is aligned with the "O" mark on the timing tab scale. Remove the compression gauge. NOTE: There are

tools available commercially which screw into the #1 spark plug hole and register (more accurately than the above methods) when top dead center is reached. If one of these tools is used, follow the tool manufacturers instructions.

2. Reinstall the #1 spark plug and connect the plug wire. With the distributor out of the vehicle and the distributor cap installed, lo cate the #1 distributor cap terminal and chalk mark its position on the distributor housing. Remove the distributor cap.

3. Position the distributor into the engine block with the:

a. vacuum advance unit in its proper

position (see the Firing Order illustra tions).

b. firing tip of the rotor pointing to the

mark made during step 2.

4. As the distributor drive gear engages, the rotor will turn slightly. If the distributor

Page 73

68 ENGINE AND ENGINE REBUILDING

DISTRIBUTOR ROTATION: CLOCKWISE

COIL

GRD. B+

FIRING ORDER

To avoid confusion, replace spark plug wires one at a time.

1963-74 except HEI

ENGINE FIRING ORDER: 1-8-4-3-6-5-7-2

1974-84 HEI

6. Install the distributor hold-down bolt

and plate. Snug down the retaining bolt.

7. Connect the vacuum advance hose, tach drive cable, and injection drive cable, on ve hicles equipped with these items.

8. Connect all wiring and adjust the igni tion timing as previously outlined.

9. Install the ignition shielding.

H.E.S. COMPONENT REPLACEMENT

Distributor Cap

1. Disconnect the feed, module, and ta

chometer wiring from the drivers side of the distributor cap. Do so by releasing the wiring connector retaining tabs and carefully pulling downward on the connectors.

2. Locate the locking tabs of the spark plug

wire retaining ring (on the distributor cap). Move each of the two locking tabs outward to release the retaining ring. With the plug wires still attached to the ring, pull the ring and wires off of the distributor cap and move the assembly out of the way.

3. Release the distributor cap hold-down

screws (push downward and counterclock wise) and lift the cap assembly off of the dis tributor.

4. Remove the coil cover from the distrib

utor cap (4 fasteners).

5. Push the spade terminals upward and

out of the distributor cap.

6. Remove the four coil screws and lift the

coil, spring, carbon contact, and rubber washer out of the distributor cap.

7. Reverse the previous steps to assemble,

using a new cap. Lubricate the rubber washer with dielectric lubricant during assembly.

housing does not sit properly on the block, the oil pump shaft is not engaging with the distributor shaft. In this case, you can do one of two things:

a. Remove the distributor and turn the oil pump driveshaft with a long screw driver to align the pump driveshaft slot with the "blade" of the distributor shaft. This is done strictly by visual approximation.

b. Apply downward pressure on the dis tributor housing (NOT the rotor) and have someone "tap" the ignition key to slowly turn the engine over until the distributor falls into its proper position. After doing this, it is recommended that you recheck the timing by repeating steps 1 and 2.

5. On conventional ignitions, after proper

positioning is assured, turn the distributor housing so that the points are just opening.

COIL

GROUND

LEAD

COIL

SECONDARY

ATTACHING

Ignition coil mounted in the HEI distributor cap

SCREW (4)

IGNITION

TERMINALS

Page 74

ENGINE AND ENGINE REBUILDING 69

MODULE

Placement of silicone dielectric compound prior

to HEI module installation

—

see text

PUT VASELINE ON

BLADE TERMINALS

GOOD CONNECTIONS ARE ESSENTIAL

SEAL

GROUND

After removing the coil, check the condition of the arc seal (1981 shown, other years similar)

Ignition Coil

CONNECTOR

Perform steps 1, 2, 4, 5, and 6 of the previous distributor cap replacment procedure. Install the new coil, being sure to use the dielectric compound supplied with most coils to lubricate the rubber washer.

Ignition Rotor

Remove the distributor cap as previously outlined. Loosen the rotor retaining screws (most screws will stay attached to the rotor) and lift the rotor off of the mainshaft assembly. During installation, note the locations of the different locating "dowels" (2) on the underside of the rotor. These dowels help to prevent incorrect rotor installation by allowing the rotor to be installed in only one way.

Vacuum Advance Unit (if so equipped)

1. Remoy/e the distributor cap and rotor as

previously outlined.

2. Disconnect the hose from the vacuum

advance unit.

3. Remove the two vacuum advance unit

retaining screws and pull the unit outward.

4. Rotate the unit to disengage the oper

ating rod from the distributor.

5. Reverse the previous steps to install.

Module

1. Remove the distributor cap and rotor as

previously outlined.

2. Carefully disconnect the wiring from the

module.

3. Remove the two module retaining screws and lift the module out of the distrib utor housing.

4. Apply a light coating of silicone dielec tric compound to the distributor housing in the module mounting area before installing the new module. The silicone compound is used to transfer heat from the module to the

APPLY

SILICONE

LUBRICANT

HERE

EXTEND RETAINING TABS TO BE SURE OF POSITIVE LOCK IN CONNECTOR

WHITE WIRE

CONNECTOR REMOVED

GREEN WIRE

(SOLDER CLIP TO WIRE)

--------

(SQUEEZE COIL TERMINALS)

Proper HEI module electrical connections

Page 75

70 ENGINE AND ENGINE REBUILDING

distributor housing. If the compound is not used, the module will overheat, causing failure of the ignition system.

NOTE: Silicone compounds are available

strictly for this purpose—DO NOT use a regular silicone lubricant or sealer.

5. Install the new module, using the ac

companying illustration as a guide to estab lish the best possible module connections.

NOTE: Many H.E.I, failures have been at-

tributed to poor module connections. Inspect the wires, terminals, and connectors for damage and follow tthe accompanying illustration.

6. Install the rotor and distributor cap as

previously outlined.

NOTE: Items previously listed are the only

items of the H.E.I, distributor which are serviceable with the distributor installed. Other services will require distributor removal and disassembly.

DISASSEMBLY

Conventional Systems

1. Remove the distributor cap and the

rotor.

2. Remove the two-piece radio interfer

ence shield (2 fasteners), if so equipped.

3. Remove the centrifugal advance

springs and weights.

4. Drive the roll pin out of the distribu tor gear using a drift no larger than die roll pin.

5. Slide the distributor gear off of the shaft and remove the spacers and washers (note their arrangement for reinstaUation).

6. Remove the tachometer drive gear.

7. Inspect the distributor shaft for burrs in the gear mounting area. If there are any burrs or nicks, carefully smooth them with a fine file. This should be done to prevent bushing damage as the distributor shaft is withdrawn from the housing.

8. Slide the distributor shaft assembly out of the housing.

9. Remove the vacuum advance unit (2 screws).

10. Carefully remove the breaker plate re taining ring and lift the breaker plate off of the distributor housing. DO NOT disassem ble the breaker plate any further.

11. Remove the point set, condenser, and the condenser mounting bracket from the breaker pkte. Remove the washer and seal from beneath the breaker plate.

Transistorized Systems

1. Remove the distributor cap and the

rotor.

2. Remove the centrifugal advance

springs and weights.

3. Remove the tachometer drive gear.

4. Support the distributor gear (to pre vent damage to the magnetic pickup assem bly) and drive the roll pin out of the gear, using a drift no larger than the roll pin.

5. Slide the distributor gear and washer off of the distributor shaft.

6. Inspect the distributor shaft for burrs in the gear mounting area. If there are any burrs or nicks, carefully smooth them with a fine file. This should be done to prevent bushing damage as the distributor shaft is withdrawn from the housing.

7. Remove the centrifugal advance weight support and timer core from the distributor shaft.

8. Disconnect the pickup coil lead con nector.

9. Remove the retaining ring which se cures the magnetic pickup assembly to the distributor housing.

10. Remove the entire magnetic pickup assembly from the distributor housing. DO NOT remove the three screws which secure the stationary pole piece to the pickup as sembly.

11. Remove the washer and felt pad from the pickup mounting.

12. Remove the vacuum advance unit.

H.E.I. Systems

1. Remove the distributor cap assembly

and rotor as previously outlined.

2. Remove the centrifugal advance springs and weights from the mainshaft, if so equipped.

3. Drive out the distributor gear roll pin using a drift.

4. Remove the distributor gear and washers. Note the location of the washers so that they may be reinstalled properly.

5. Slide the distributor shaft out of the housing.

6. Disconnect the electrical leads from the module and remove the module. Also re move the capacitor.

7. If the internal teeth of the pickup as sembly are fully exposed; remove the pickup retaining ring and remove the pickup assem bly from the distributor housing (Do not re move the three screws from the pickup as-

Page 76

ENGINE AND ENGINE REBUILDING 71

THRU

sembly). If the internal teeth of the pickup are not fully exposed; remove the magnetic shield from the pickup assembly (three attaching screws). Remove the pickup assembly retaining ring and remove the pickup components (magnet, pole piece, pickup coil).

8. Remove the vacuum advance unit, if so equipped.

ASSEMBLY

Assembly of the distributor is the reverse of its respective disassembly procedure.

When assembling the distributor, be sure to lubricate the distributor shaft bushings with a few drops of engine oil. Also be sure that the distributor shaft turns freely after it is installed. On conventional, point-type distributors, it is easier to install and gap the points while the distributor is removed.

On H.E.I, systems, apply a light coating of silicone dielectric compound to the distributor housing in the module mounting area before installing the module. The silicone compound is used to transfer heat from the module to the distributor housing. If the compound is not used, the module will overheat, causing failure of the ignition system. NOTE: Silicone compounds are available

strictly for this purpose—DO NOT use a regular silicone lubricant or sealer. Refer to

the previous middle replacement procedure for additional module installation information.

Alternator

The alternating current generator (alternator) supplies a continuous amount of electrical energy at all engine speeds to keep the battery fully charged. The Corvette, as all other GM vehicles, uses a Delcotron alternator. Delcotron is a trade name of the Delco-designed alternator.

The alternator consists of four main assemblies: drive (pulley) end frame, slip ring (rear) end frame, stator, and rotor. The drive end frame houses a ball bearing which is used to support the front of the rotor and is large enough to withstand the side loads imposed on the rotor by the alternator belt. The slip ring end frame uses a small roller bearing which is used to support the rear of the rotor (The "perforated case" Delcotron uses a ball bearing in the rear, also). These bearings are lubricated during their assembly and need no additional lubrication. If you replace the bearings, try to obtain a fully sealed bearing for the front, to further increase bearing life.

The stator has a laminated core which is attached to the frame of the alternator. On "perforated case" models, the stator is serviced with the main case. A large number of windings cover the inside diameter of the stator, and it is within this circle that the rotor turns. Current passes from two brushes through the slip rings (of the rotor) and finally to the field coils which are wound in a manner concentric to the rotor shaft.

RELAY TERMINAL / »

Externally regulated Delcotron—except "perforated case" models

" TERMINAL

"ORD" TERMINAL

BRUSH AND gOLT -*

TERMINAL ASSEMBtY

SUP RINGS

BEARING-/

DIODES

SUP RING DRIVE END

BEARING

ROTOR

END FRAME FRAME

Page 77

72 ENGINE AND ENGINE REBUILDING

FAN

RESERVOIR

WINDING •

RELAY

SUP RING

DRIVE

TERMINAL

BEARING

ASSEMBLY

"BATT"

ROTOR

PUUEV

GREASE

FIELD

TERMINAL

Externally regulated, "perforated case" Delcotron

Both the internally and externally regulated Delcotrons use positive and negative diodes. These diodes are electrical chedk valves, meaning that they will allow current to pass freely in only one direction. The diodes perform the function of changing the alternating current (AC) developed within the stator windings to direct current (DC) which can be used by the 12VDC system. In the

NO. i

NO, 1

TERMINAL

',. S1A10R afitu.

externally regulated Delcotron (except the "perforated case" models), the negative diodes (3) are pressed into die slip ring end frame; the positive diodes (3) are pressed into an electrically insulated heat sink attached to the slip ring end frame. The diodes used in the "perforated case" Delcotron are pressed into removable heat sinks. The grounded heat sink contains the negative diodes; the insulated

END FRAME END FRAME |

STATOR

Internally regulated Delcotron

Page 78

ENGINE AND ENGINE REBUILDING 73

contains the positive. InternaDy regulated

Delcotrons use a different type of diode ar-

rangement. In these models, the negative

diodes are permanently mounted in a rec-

tifier bridge assembly. The rectifier bridge

utilizes a finned aluminum heat sink for

efficient diode cooling, and is mounted inside

the slip ring end frame. A positive diode trio

is used instead of separately mounted posi-

tive diodes. If a negative diode of the rectifier

bridge fails, the rectifier bridge assembly

must be replaced. Also, the positive diode

trio can only be replaced as a unit.

Generally, internally and externally regulated alternators can easily be distinguished by the type of plug-in connector which is used at the alternator. External regulator models use a connector having two side-by-side vertical spade terminals, whereas the internal regulator type uses a connector having two side-by-side horizontal spade terminals. All "perforated case" Delcotrons use external voltage regulators.

Adjustments can be made to the external type of regulator (covered later in this section). The internally mounted voltage regulator is non-adjustable—if it is defective, it must be replaced.

ALTERNATOR PRECAUTIONS

To prevent damage to the alternator and regulator, the following precautions should be taken when working with the electrical system.

1. Never reverse the battery connec

tions.

2. Booster batteries for starting must be connected properly—positive-to-positive and negative-to-negative.

3. Disconnect the battery cables before using a fast charger; the charger has a ten dency to force current through the diodes in the opposite direction for which they were designed. This burns out the diodes.

4. Never use a fast charger as a booster for starting the vehicle.

5. Never disconnect the voltage regula tor while the engine is running.

6. Avoid long soldering times when re placing diodes or transistors. Prolonged heat is damaging to AC generators.

7. Do not use test lamps of more than 12 volts (V) for checking diode continuity.

8. Do not short across or ground any of the terminals on the AC generator.

9. The polarity of the battery, generator, and regulator must be matched and con-

sidered before making any electrical connections within the system.

10. Never operate the alternator on an open circuit. Make sure that all connections within the circuit are clean and tight.

11. Disconnect the battery terminals when performing any service on the electrical sys tem. This will eliminate the possibility of ac cidental reversal of polarity.

12. Disconnect the battery ground cable if arc welding is to be done on any part of the car.

EXTERNALLY REGULATED ON-CAR CHARGING SYSTEM TESTS

isolation Checks

These are quick checks that will allow the tester to isolate the general source of charging circuit difficulty in either the alternator, regulator, or wiring harness. Once the defective component has been singled out, further checks and repairs may be made using the procedures given in the alternator or regulator sections. Make these checks after looking for obvious problems such as a weak battery or loose fan belt.

Start the engine and bring the idle to between 1500-2000 rpm. Turn off all accessories, lights, radio, etc., and then disconnect the battery ground cable. If the engine stops, it is safe to assume that the alternator is at fault. If, however, the engine continues to operate, the problem lies with either the regulator or wiring harness.

Having eliminated the alternator from suspicion, the next step is to isolate the regulator from the harness and the easiest way is to substitute a known component. Remove the push-on wiring connector from the regulator and insert a regulator that is known to be good into the circuit, remembering to ground the regulator to the car. Idle the engine, remove the battery cable, and check the ammeter. If it indicates a discharge condition, then the possible problem is an open resistor or a shorted, positive diode. If the ammeter continues to indicate a charge, then it is the regulator that is defective.

Alternator Tests

Prepare the alternator for testing by disconnecting the battery ground terminal, the BAT, light relay, field, and GRD leads from the alternator terminals.

Check the positive diodes by connecting an

ohmmeter between the R (or light relay) and

Page 79

74 ENGINE AND ENGINE REBUILDING

END

HOLE

Ground this tab to test the alternator voltage out

BAT terminals, and noting the lowest range on the ohmmeter scale. It should indicate very low resistance. Reversing the connections should result in an infinitely high resistance indication. If the ohmmeter reads low or high in both directions, the diodes, are defective. A low reading could also indicate a grounded stator. To test for an open field, connect the ohmmeter between the F (or Field) and GRD terminals and check the low range scale for a reading between 7 and 20 ohms. A zero indication or one of excessively high resistance suggests a faulty alternator.

NOTE: The 17SI alternator used on the

1984 Corvette uses delta stator windings and cannot be checked for an open circuit.

Field Relay Tests

Fasten one voltmeter lead to the no. two regulator terminal and ground the other lead to the regulator. Idle the engine between 1500 and 2000 rpm. If the GEN light still burns, and a volt reading of 3.5 to 6.5 is present, then the regulator field relay is faulty.

Accessory Circuit Resistance Tests

A resistor is connected to the ACC terminal ignition switch. To check for an open resistor, connect the voltmeter to the no. 4 connection of the regulator and ground the other voltmeter lead to the regulator. A zero reading, with the ignition switch turned to the ACC notch, indicates an open resistor. The resistance wire is an integral part of the ignition harness and carries a rating minimum of 10 ohms, 6.25 watts. The wire is not solderable and must be crimp-connected.

speed and adjust the carbon pile to obtain maximum alternator output as indicated on the ammeter. If output is within 10% of rated output as stamped on the alternator frame, alternator is O.K. If output is not within specifications, ground the alternator field by inserting a screwdriver into the test hole in the end frame. If output now is within 10% of rating, replace the voltage regulator; if still not within specifications, check field winding, diode trio, rectifier bridge and stator, as described later.

Low Charging Rate Diagnosis

1. After battery condition, drive belt ten sion, and wiring terminals and connections have been checked, charge the battery fully and perform the following test:

2. Connect a test voltmeter between the alternator BAT, terminal and ground, igni tion switch on. Connect the voltmeter in turn to alternator terminals No. 1 and No. 2, the other voltmeter lead being grounded as be fore. A zero reading indicates an open circuit between the battery and each connection at the alternator. If this test discloses no faults in the wiring, proceed to Step 3.

3. Connect the test voltmeter to the alter nator BAT terminal (the other test lead to

INSERT SCREWDRIVER GROUND TAB TO END FRAME

TAB

INTERNALLY REGULATED SYSTEM TESTING

Alternator Output Test

1. Connect a test voltmeter, ammeter, and a 10-ohm, 6-watt resistor into the charging circuit. Do not connect the carbon pile to the battery posts at this time.

2. Increase alternator speed and observe the voltmeter—if the voltage is uncontrolled with speed and increases to 16 volts Or more, check for a grounded brush lead clip as pre viously covered. If a brush lead clip is not grounded, the voltage regulator is faulty and must be replaced.

3. Connect the carbon pile load to the bat tery terminals.

4. Operate the alternator at moderate

FRAME

put—Internally regulated Delcotron only

Page 80

ENGINE AND ENGINE REBUILDING 75

ground), start the engine and run at 1,5002,000 rpm with all lights and electrical accessories turned on. If the voltmeter reads 12.8 volts or greater, the alternator is good and no further checks need be made. If the voltmeter reads less than 12.8 volts, ground the field winding by inserting a screwdriver into the test hole in the end frame.

CAUTION: Do not force the tab more than % in. into the end frame.

a. If voltage increases to 13 volts or

more, the regulator unit is defective;

b. If voltage does not increase signifi

cantly, the generator is defective.

High Charging Rate Diagnosis

1. With the battery fully charged, connect a voltmeter between alternator terminal No. 2 and ground. If the reading is zero, No. 2 circuit from the battery is open.

2. If No. 2 circuit is OK, but an obvious overcharging condition still exists, proceed as follows:

a. Remove the alternator and separate

the end frames;

b. Connect a low-range ohmmeter be tween the brush lead clip arid the end frame (Test 1), then reverse the connections. If both readings are zero, either the brush lead clip is grounded or the regulator is de fective. A grounded brush lead clip can be due to damaged insulating sleeve or omis sion of the insulating washer.

REMOVAL AND INSTALLATION

1. Disconnect the negative battery cable at the battery; this will prevent damaging the alternator diodes.

2. Disconnect the wiring from the rear of the alternator (bolt-on and push-in connec tors).

3. Loosen the lower alternator bolt and re move the upper (adjustment) bolt. Slip the drive belt off of the pulley.

4. Remove the pivot bolt and lift the alter nator out of its mounting brackets.

5. Installation of the alternator is the re verse of the previous steps. Adjust the drive belt to the proper tension.

DISASSEMBLY AND ASSEMBLY

Externally Regulated Type—Except "Perforated Case" Models

Remove the pulley by positioning a box-end wrench over the pulley retaining nut and inserting a 5/i6 in. alien wrench in the shaft to

prevent it from turning. Unbolt the retaining nut and slide it off the pulley. Disconnect the battery ground strap to prevent diode damage and remove the generator. On the 6.2 in. perforated case generator, remove the bladeconnector retaining nuts and remove the connectors. Slip the indicator light relay from the terminal post, then back out die retaining screws, and remove the brush holder. Leave the capacitor attached to the generator. Remove the four, long, case bolts and separate the end frame and rotor assembly from the stator assembly. Cover the slip ring and bearing with tape to prevent contamination.

Remove the rotor from the end frame. Extract the retainer plate screws and remove the retainer plate and the end frame bearing. Remove the three attaching screws and separate the stator from the end frame. Remove the heat sink.

Wash all metal parts with the exception of

the stator and rotor assemblies. The rotor slip rings may be cleaned with 400 grain polishing cloth. It is a good idea to rotate the rotor while doing this to guard against rubbing flat spots on the slip rings. Maximum out-of-round tolerance for sh'p rings is 01001 in. Remove as little metal as possible when truing on a lathe. Polish with 400 grain cloth and blow dry. To assemble the alternator: Attach the slip-ring end frame to the stator assembly and position the diode connectors above the diode, relay, and stator leads. Tighten the terminal nuts, then slide the front end frame over the rotor. Slide on the spacer, pulley, washer, and nut, and torque the shaft to 5060 ft. Ibs. Attach the slip-ring end frame and stator to the rotor and drive end frame assembly and insert and tighten the thrubolts.

Externally Regulated Type—"Perforated Case" Models

1. Mount the alternator in a vise, clamp ing the drive end mounting flange length wise.

2. Remove the two screws which secure the cover to the brush holder and remove the cover.

3. Remove the nut which retains the in dicator light wire to the bkde connector post. Disconnect the wire from the connector post.

4. Remove the two brush holder assem bly attaching screws and remove the brush holder.

NOTE: The capacitor lead is connected in-

side the alternator; the capacitor must stay

Page 81

76 ENGINE AND ENGINE REBUILDING

with the alternator to avoid overstressing the lead wire.

5. Scribe alignment marks to indicate the relationships between the end frames and the main base. These components must be prop erly aligned during assembly.

6. Remove the slip ring (rear) end frame attaching bolts (3) and carefully pry the end frame off of the main case assembly. Pry around the circumference of the frame to avoid damaging the frame.

7. Remove the drive end frame attaching bolts (3).

8. Remove the end frame, rotor, and pul ley as an assembly.

9. Remove the shaft nut, washer, pulley, and woodruff key from the rotor shaft and slide the rotor out of the end frame.

10. If you plan to test the diodes and stator, disconnect the stator leads from the diodes using either of the following meth ods.

a. Cut the leads between the stator

windings and the diodes

b. Scrape the epoxy coatings from the

leads and unsolder die leads from the diodes. CAUTION: If you choose method "b", be

sure to use a minimum amount of heat to avoid damage to the diodes.

11. Remove the heat sink retaining screws and remove the heat sinks. Remember that the insulated heat sink contains the positive diodes and that the insulated heat sink is the one with the "batt" terminal.

12. Testing and/or replacement of bear ings or diodes should be performed at this time, if necessary.

Assembly of the alternator is the reverse of

the previous steps. Note the following points during assembly:

a. Refer to the illustration which accompanies the "Brush and Holder Replacement" procedure for wiring informa tion.

b. Solder the stator lead-to-diode con

nections, if separated during step 10.

c. Align the scribed marks made during

disassembly.

d. Lightly clamp the pulley in a soft-

jawed vise when installing the pulley nut. Torque the pulley nut to 50-60 ft. Ibs.

e. When installing the brush holder, push each brush into the holder and retain with a straightened paper clip during in stallation. Remove the clip after the holder is installed.

Internally Reglated Type

1. Place alternator in a vise, clamped by

the mounting flange only.

2. Remove the four through bolts and separate the slip ring end frame and stator assembly from the drive end and rotor as sembly, using a screwdriver to pry the two sections apart. Use the slots provided for the purpose.

NOTE: Scribe matchmarks on the parts to

aid in assembly.

3. Place a piece of tape over the slip ring end frame bearing to prevent entry of dirt; also tape shaft at slip ring end to prevent scratches.

4. Clean brushes, if they are to be reused, with trichloroethylene or carbon tetrachloride solvent. Use these solvents only in an adequately ventilated area.

5. Remove the stator lead nuts and sepa rate the stator from the end frame.

6. Remove the screw that secures the diode trio and remove diode trio.

NOTE: At this point, test the rotor, recti-

fier bridge, stator and diode trio if these tests are necessary.

1. Remove the rectifier bridge hold-down

screw and the BAT terminal screw, then disconnect condenser lead. Remove rectifier bridge from end frame.

8. Remove the two securing screws and brush holder and regulator assemblies. Note the insulating sleeves over the screws.

9. Remove the retaining screw and con denser from the end frame.

10. Remove the slip ring end frame bear ing, if it is to be replaced, using the proce dure given later in this section.

11. Remove the pulley nut, washer, pul ley, fan and spacer from the rotor shaft, using a 5/ie in. alien key to hold the shaft while loosening the nut.

12. Remove rotor and spacers from drive end frame assembly.

13. Remove drive end frame bearing re tainer plate, screws, plate, bearing, and slinger from end frame, if necessary.

14. To assemble, reverse order of disas sembly. Pulley nut must be tightened to 4050 ft. Ibs.

CLEANING AND INSPECTION

1. Clean all metal parts, except stator and

rotor assemblies, in solvent.

2. Wipe off bearings and inspect them for

pitting or roughness.

Page 82

ENGINE AND ENGINE REBUILDING 77

CHECK FOR OPENS

GROUNDS)

OHMMETER

3. Inspect rotor slip rings for scoring. They may be cleaned with 400 grit sandpaper (not emery), rotating the rotor to make the rings concentric. Maximum out-of-true is 0.001 in. If slip rings are deeply scored, the entire ro tor must be replaced as a unit.

4. Inspect brushes for wear; minimum length is ¥4 in.

ALTERNATOR COMPONENT TESTING

Rotor *

Attach one lead of a 110 volt test lamp or an ohmmeter to either slip ring, and the other lead to the rotor shaft or poles. A lighted test lamp or low ohmmeter reading indicates grounded field windings.

Attach the lamp or ohmmeter connections to each slip ring. The windings are open if the lamp fails to light or the ohmmeter reading is high.

Connect a 12 volt battery and an ammeter in series with the slip rings to check for shorts. The windings are shorted if the reading exceeds 1.5 amps. An ohmmeter may be substituted for the same check and will show a resistance reading of less than 6 ohms if the windings are shorted.

(CHECK FOR OPENS)

TESTING STATOR

OHMMETER

(CHECK FOR

OPENS)

Stator testing—except "perforated case" models

OHMMETER (CHECK FOR

Stator

Attach the test lamp or ohmmeter to the stator frame and one of the stator leads. A lighted lamp or low resistance reading indicates grounded windings.

Successively connect the test equipment between each pair of stator leads. Open windings will produce a high resistance and prevent the test lamp from lighting.

Shorts require special test equipment. If

(CHECK FOR TESTING ROTOR

OHMMETER

Rotor testing

GROUNDSKOHMMETER).

Page 83

OHMMETER

Stator testing—"perforated case" models

Page 84

78 ENGINE AND ENGINE REBUILDING

WASHER

all other tests fail to locate the problem, it is more than likely a short in the stator.

Separately Mounted Diodes (Pressed-in Type)

The diodes may be checked for shorts or opens by using an ohmmeter or a 12 volt test lamp.

CAUTION: Under no circumstances use a

110 volt test lamp.

Use a V/z volt cell ohmmeter that has been adjusted to the lowest range scale. Attach one lead to me heat sink and the other to the diode lead. A good diode will show a high and a low reading depending on the connection switch. Two low or two high readings signal a faulty diode. Check the other diodes in the same manner. When servicing "perforated case" models, repeat this for the diodes in BOTH heat sinks.

Check the end-frame mounted diodes by connecting one test lead to the frame and the other to the diode lead. Reverse the connection and check the readings. The same diagnosis is true here as for the heat sink diodes.

If an ohmmeter is not available, substitute a 12 volt test lamp. Connect and switch connections in the same fashion as with the ohmmeter. The lamp will light in only one direction. If it lights or fails to light in both directions, the diode is bad.

Diode Rectifier Bridge

Refer to the accompanying illustration for component identification. Use a self-powered ohmmeter set on its lowest reading scale.

CAUTION: DO NOT use a 110 volt test

lamp to test the rectifier bridge—use only a self-powered ohmmeter.

Connect one ohmmeter lead to the grounded heat sink. Connect the other lead to each of the three rectifier bridge terminals (one at a time) and note the ohmmeter readings (1st set). The readings at each of the bridge terminals should be virtually identical. Reverse the ohmmeter leads and repeat the test, again noting the meter readings (2nd set).

Connect one ohmmeter lead to the insulated heat sink. Connect the other lead to each of the three rectifier bridge terminals (one at a time) and note the ohmmeter readings (3rd set). Reverse the ohmmeter leads and repeat the test, again noting the meter readings (4th set).

Readings taken for any one full set should be virtually identical, conversely, if you get two different readings WITHIN the same set, replace the rectifier bridge assembly. When comparing readings between sets 1 and 2, one set should read high, the other low. When comparing readings between sets 3 and 4, again, one set should be high, the other low.

TESTING RECTIFIER BRIDGE

BRUSH ^-<^=5r==^>^ REGULATOR HOLDER

Diode check Rectifier bridge check

TEST LAMP

TEST IAMP

INSULATING

OHMMETER

Page 85

ENGINE AND ENGINE REBUILDING 79

BRIDGE

Diode trio

check

END FRAME VIEW

INSULATING _

WASHERS ^ij^^^^^^^^s: (USED ON

RECTIFIER

CAPACITOR

Location of diode trio

Diode Trio

i ______

NUTS

RESISTOR

SOME MODE LSI

DIOD

CAUTION: DO NOT use a 110 volt test lamp to test the diode trio—use only a selfpowered ohmmeter. Set the ohmmeter lead to the single terminal of the diode trio. Connect the other lead to each terminal (one at a time) of the three terminal grouping, and note the ohmmeter reading at each terminal (1st set). Reverse the ohmmeter leads and repeat the same test, again noting the ohmmeter readings (2nd set). Ohmmeter readings WITHIN one set should be virtually identical. When comparing readings BETWEEN each set, one set should be high, the other low.

TESTING TRIO

OHMMETER

SINGLE CONNECTOR

REPAIRS

Pressed-in Diode Replacement

Despite rumors to the contrary, diodes of this type may be replaced. It is not necessary to replace me entire generator assembly as some unscrupulous garage owners convinced their unwary customers in the introductory days of the AC generator.

Two types of diodes, positive and negative, are used in the AC generator. The heat sink contains the positive diodes and these are marked with red. End frame diodes are the negative ones and they have black markings. Do not attempt to drive a diode from its bore or the other diodes may be damaged.

Support the end frame in an arbor press-, select a suitable removal spacer, and press the diode from the frame. Use the same method to install a replacement diode.

To replace heat sink diodes (which includes all of the diodes of "perforated case" models), it is necessary to separate the heat sink from the frame. Observe the stack-up closely to ensure correct reassembly of the BAT and GRD terminal bolts. Replace the diodes as described above, reassemble the bolt stack-ups and attach the heat sink to the end frame.

Bearing Replacement

The drive end frame bearing is removed by detaching the retainer frame from the end plate and pressing the bearing out. Fill the bearing Yi full with multipurpose grease; do not overfill. Press the bearing into the end frame. Install the retainer pkte.

The slip ring end frame bearing of the 6 in. "perforated-case" generator is pressed off the rotor shaft. The replacement is pressed over the rotor shaft by using an arbor press.

The 5.5 in. aluminum Delcotron slip-ring end bearing is replaced by pressing it out towards the inside of the case. To install the replacement, position a flat plate over the bearing and press it into the outside of the case. Press all bearings and diodes flush with their receptacles.

THREE CONNECTORS

Brush and Holder Replacement

NOTE: It is always easier and worth the minimal extra cost to replace the brushes with their holder. For some models, brushes themselves are not serviced separately. For

externally regulated models, except the "perforated case" Delcotron:

Page 86

80 ENGINE AND ENGINE REBUILDING

BRUS

Brush holder

—

Externally regulated Delcotron, ex

CONDENSER

LEAD

cept "perforated case" models

Brush holder wiring—"perforated case" Delcotron

placement of the internal voltage regulator.

1. Remove two brush holder screws and stator lead to strap nut and washer, brush holder screws and one of the diode trio lead strap attaching screws.

NOTE: The insulating washers must be re-

placed in the same position on reassembly.

2. Remove brush holder and brushes. The

voltage regulator may also be removed at this time, if desired.

3. Brushes and brush springs must be free of corrosion and must be undamaged and completely free of oil or grease.

BSUSH HOIDER GROUND CONDENSER

MOUNTING SCREW STUD LEAD

Brush holder—"perforated case" Delcotron

1. Remove the stator lead nut that also

holds the relay terminal connector.

2. Remove the two mounting screws and

the brush holder assembly.

3. When installing the new brush holder assembly, depress the brushes and insert a straightened paper clip through the holes provided in the holder for brush retention.

4. Install the brush holder assembly.

5. Remove the paper clip after the alter nator is assembled.

For externally regukted models of the

"perforated case type:

If the alternator was disassembled according to the previous procedure, just install the new brush holder during assembly. If the alternator has not yet been disassembled, refer to steps 1—4 and 12e of the previous Disassembly and Assembly procedure to replace the brush holder. For internally regulated Delcotrons:

NOTE: This procedure also includes re-

4. Insert spring and brushes into holder, noting whether they slide freely without binding. Insert wooden or plastic toothpick into bottom hole in holder to retain brushes.

NOTE: The brush holder is serviced as a

unit; individual parts are not available.

5. Reassemble in reverse order of disas

sembly.

Voltage Regulator

Three types of voltage regulators have been used in the Corvette since 1963. The first type of regulator, hereafter referred to as Type One, is a double-contact model which is mounted externally, separately from the alternator. The Type One regulator was used on most 1963-68 and some 1969 Corvettes. This regulator is housed in a basically square, black metal case and has four electrical terminals.

The second type of regulator, hereafter called Type Two, is a transistorized model which was offered as an option with the transistorized ignition system in 1965. The Type Two regulator is externally mounted and uses: a) one transistor which assists in limiting the voltage to a preset value, and b) two diodes

Page 87

ENGINE AND ENGINE REBUILDING 81

FIELD RELAY

TERMINAL

ACCESS PLUG TO

VOLTAGE ADJUSTMENT

"LATCH"

"F" TERMINAL

NO. 2 TERMINAL NO. 3

TERMINAL NO. 4

Type One voltage regulator

"F" TERMINAL NO. 2

TERMINAL NO. 3 TERMINAL NO. 4 TERMINAL

Type Two voltage regulator

which protect the system from transient voltage which may occur. The Type Two regulator is easily identified by the finned regulator casing.

The third type of regulator, hereafter called Type Three, is mounted inside of the Delcotron alternator. This electronic regulator, used in some 1969 and all later Corvettes, is nonadjustable and must be replaced if defective.

properly grounded and do not overtighten the mounting screws, as this will cancel the cushioning effect of the rubber grommets.

Type Three

1. Remove the alternator from the vehicle

as previously outlined.

2. Scribe a line on the alternator case from front-to-rear which will aid in attaining the proper relationships between components during assembly.

3. Remove the four through-bolts which join the end frame assemblies.

4. Separate the end frames by carefully prying between the drive (front) end frame and the stator. DO NOT pry between the slip ring (rear) end frame and the stator. The sta tor is wired to the rectifier bridge which is attached within the rear end frame.

5. Disconnect the three stator wire termi nals at the rectifier bridge connections.

6. Remove the stator from the slip ring end frame. It may be necessary to carefully pry the stator from the frame.

7. Remove the three screws which retain the brush holder and regulator. Note the po sitions of the two screws which are equipped with plastic insulating washers—these screws MUST be installed in their original locations.

NOTE: Some alternators also have a resis-

tor which is installed between the regulator and brush ground terminals. Note its position and reinstall it in the same manner.

8. Lift the brush holder and regulator out of the alternator frame.

9. The regulator is installed in the reverse of the previous steps. Before installing the brush holder, push the brushes into the holder and insert a straightened paper clip through the holes provided in the holder for brush retention. Remove the paper clip after the alternator is assembled.

REMOVAL AND INSTALLATION Types One and

Two

1. Disconnect the negative battery cable

at the battery.

2. Disconnect the wiring harness from the

regulator.

3. Remove the regulator mounting screws

and remove the regulator.

4. Installation is the reverse of the pre

vious steps. Be sure that the regulator base is

VOLTAGE ADJUSTMENT

Types One and Two Only

The adjustment procedure is the same for both types of regulators, except for the loca tions where the adjustment is made. On the Type One regulator, the adjustment screw is under the regulator cover; the Type Two regulator is adjusted externally after removing the alien screw from the adjustment screw access hole.

1. Insert a % ohm-25 watt fixed resistor

into the charging circuit at the horn relay

Page 88

82 ENGINE AND ENGINE REBUILDING

REGULATOR

AIR GAP

ONLY

ADJUSTING SCREW

VOLTMETER

Schematic for testing the regulator voltage setting

junction block, as shown in the accompanying illustration.

2. Install a voltmeter as shown in the ac

companying illustration.

3. Warm the engine by running it for

about fifteen minutes at 1500 rpm or more.

4. Disconnect the regulator connector and

reconnect it to cycle the regulator.

5. Read the voltage on the voltmeter. If the voltage reading is 13.5-15.2 volts, the regulator does not need adjustment or re placement. If the voltage is not within these limits, leave the engine running at 1500 rpm and proceed to step 6.

6. On Type One regulators, disconnect the regulator connector and remove the reg ulator cover. Reconnect the regulator con nector. On Type Two regulators, remove the adjustment screw access plug from the regu lator case (the plug is actually an alien screw).

7. Observe the voltmeter reading and turn the voltage adjustment screw until the voltmeter reads 14.2-14.6 volts.

8. On Type One regulators, disconnect

ADJUSTING NUT

(TURN TO ADJUST VOLTAGE SETTING)

Type One voltage regulator—voltage adjustment

the regulator connector, install the cover and reconnect the regulator connector.

9. Continue running the engine at 1500

rpm to re-establish the internal temperature of the regulator (Type One only).

10. Again, cycle the regulator by discon necting and reconnecting the regulator con nector.

11. Recheck the voltmeter reading: If it is between 13.5 and 15.2 volts, the regulator is good; is not, replace the regulator.

CAUTION: On Type One regulators, al-

ways disconnect the regulator connector before removing the regulator cover, to prevent short circuits.

12. On Type Two regulators, If the volt meter reading is okay, reinstall the access hole plug.

VOLTAGE TESTING

Type Three Regulator Only

Though other tests of the internal voltage regulator exist, the following test is quite accurate and requires a minimum of tools. NOTE: The following test must be per-

formed with the engine at normal operating temperature.

1. Attach one lead of a voltmeter to the "BAT" terminal of the alternator and the other lead to a good ground.

2. Start the engine and operate at about 1500 rpm.

3. Observe the voltmeter reading: If it is approximately 13.5-15.2 volts, the regulator is properly limiting the voltage to the bat tery. If the voltage is above about 15.2 volts, replace the voltage regulator as previously described. If the voltage is below 13 volts, locate the test hole in the rear end frame of

Page 89

ENGINE AND ENGINE REBUILDING 83

REGULATOR

Starter mounting

—

small block (top) and big block

(bottom)

the alternator (refer to the illustration under Alternator Tests.) Insert a screwdriver into the test hole about %" to depress the field grounding tab. Under no circumstances should you push the screwdriver further than 1" into the alternator. If the voltage reading increases as the screwdriver is put into the test hole, the alternator is functioning properly and the regulator must be replaced. If the voltage reading did not increase with the insertion of the screwdriver, the alternator must be disassembled and tested.

NOTE: If the test hole is not accessible, re-

move the alternator and test the following components: rotor, stator, rectifier bridge, diode trio, and brushes (%," minimum length). Replace any component which may be defective. If these components are okay, replace the voltage regulator.

TESTING TYPE THREE REGULATOR OFF THE CAR

NOTE: This test requires the use of a fast charger.

1. Remove the voltage regulator from the

alternator.

2. Connect voltmeter and fast charger to

battery as shown.

3. Connect regulator and test light as

shown, observing battery polarity.

4. The test light should be on when con

nected.

5. Turn on the fast charger and slowly in crease the charge rate. Check the voltmeter and make sure that the test light goes out at a minimum of 13.5 volts, and a maximum of

16.0 volts.

Starter

REMOVAL AND INSTALLATION

1. Disconnect the battery cables at the

battery.

2. Raise the front of the vehicle to a con venient working height and support with jackstands.

3. Disconnect the wiring from the starter solenoid. Replace each connector nut as the terminals are removed as the thread sizes dif fer between connectors. Note or tag the wir ing positions to avoid improper connections during installation.

4. Remove the front starter support bracket and the heat shield (if so equipped).

voltage regulator on the bench

TRANSISTORIZED

TEST LIGHT Testing

Page 90

Year

1963-64 1965-67

1968

1969 1970

1971-72

1100628 1100693 1100696 1100693 1100794 1100696 1100696 1100900 .1100901 1100544 1100543,1100950 1100566

Model

m z

m >

z o

m 3D m co

Alternator and Regulator Specifications

Regulator

Volts to

Regulator

Air Gap (in.)

0.067 0.014 13.8-14.8

Point

Gap (in.)

Volts at

125°

Alternator

Output @

Field Current

Draw

@12V

1 .9-2.3

2.2-2.6

2.2-2.6 4-4.5 4-4.5

2.2-2.6

Generator RPM

2000

27A 37A 27A 37A 29A 42A 27A 37A 27A 37A 29A 42A 27A 37A 27A 37A

27A 37A ® ® ® 37A

25A 35A

5000

Model

1119512 0.015 0.030 2.3-3.7 0.067 0.014 13.5-14.4 1119515 0.015 0.030 2.3-3.7 0.067 0.014 13.5-14.4 1119515 0.015 0.030 2.3-3.7 0.067 0.014 13.5-14.4 1119515 0.015 0.030 2.3-3.7 0.067 0.014 13.5-14.4 1119515 0.015 0.030 2.3-3.7 0.067 0.014 13.5-14.4 1119515 0.015 0.030 2.3-3.7 0.067 0.014 13.5-14.4 1119515 0.015 0.030 2.3-3.7 0.067 0.014 13.5-14.4 1119515 0.015 0.030 2.3-3.7 0.067 0.014 13.5-14.4

1119515 .0.015

1119515 0.015 0.030 1.5-3.2 1119515 0.015 0.030 1.5-3.2 1119515 0.015 0.030 1.5-3.2

Field Relay

Air

Gap

(in.)

Point

Gap (in.)

0.030 2.3-3.7 0.067 0.014 13.5-14.4

Page 91

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ENGINE AND ENGINE REBUILDING 85

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Page 92

86 ENGINE AND ENGINE REBUILDING

5. Loosen the two main starter mounting bolts, support the starter and remove the bolts. Lower the starter front end first and remove the starter.

6. Reverse the previous steps to install the starter. Torque the two main starter mount ing bolts to 25-35 ft. Ibs.

STARTER OVERHAUL

Drive Replacement

1. Disconnect the field coil straps from

the solenoid.

2. Remove the two starter through bolts. Separate the commutator end frame, field frame, drive housing, and armature from each other.

3. Slide the two-piece thrust collar off of the end of the armature shaft.

4. Slide a %" deep socket or a piece of pipe of suitable size over the drive end of the armature shaft and against the snap-ring re tainer. Carefully tap the socket or pipe to wards the armature to drive the retainer off of the snap-ring.

5. Remove the snap-ring from the arma ture shaft. Be careful, as the snap ring will

Use a piece of pipe to drive the retainer toward the snap-ring

distort rather easily. If the snap ring is distorted after removal, it must be replaced.

6. Slide the starter drive and retainer

from the armature shaft.

1. Commutator end frame

2. Bushing (not pictured)

3. Brush

4. Brush holder

5. Brush and holder package

6. Field and frame assembly

7. Washer

8. Armature

9. Drive assembly

10. Retainer

15 16

11. Snap-ring

12. Thrust washer

13. Drive end housing

14. Bushing (not pictured)

15. Solenoid assembly

16. Plunger spring

17. Plunger.

18. Lever

19. Roll pin

20. Lever pivot bolt

Exploded view of the starter

19 18

21. Lever bolt nut

22. Through bolt

23. Through bolt

24. Brush screw

25. Bolt

26. Field retaining screw

27. Plug

28. Grommet

Page 93

ENGINE AND ENGINE REBUILDING 87

7. To reassemble, lubricate the drive end of the armature shaft with silicone lubricant and slide the starter drive onto the shaft with the pinion gear facing away from the arma ture. Slide the retainer onto the shaft with the cupped portion facing away from the ar mature.

8. Support the armature assembly in a vertical fashion with the drive end pointing upward. Position the snap ring on the top of the shaft, and carefully place a block of wood on the snap ring. Keep the snap ring cen tered. Tap the block of wood to drive the snap ring onto the shaft. Using a deep socket that will fit around the shaft without interference and yet contact the snap ring, force the snap ring downward into its groove on the shaft.

9. Place the thrust washer on the shaft. Using two pairs of pliers as shown in the ac companying illustration, force the snap-ring retainer over the snap ring and engage it with the thrust washer.

10. Lubricate the drive housing bushing

with silicone lubricant. Install the armature and clutch assembly into the drive housing, engaging the solenoid shift lever with the clutch, and positioning the front end of the armature shaft into the drive housing bushing.

11. Apply a sealing compound (G.M. #1050026 or its equivalent) to the drive housing around the area where the field frame mates with the housing.

12. Slide the field frame assembly over the armature and guide the brushes over the ar mature commutator. Continue to push the field frame until the frame mates to the drive housing. Work slowly and carefully to pre vent brush damage.

13. Lubricate the bushing in the commu tator end frame with silicone lubricant, being careful not to get the lubricant on surround ing components.

14. Place the leather washer onto the ar mature shaft and slide the commutator end frame over the shaft and into position against the field frame. Line up the bolt holes, then install and tighten the two starter through bolts.

NOTE: If replacement of the starter drive

fails to cure improper engagement of the starter pinion to the flywheel, there are probably defective parts in the solenoid and/or shift lever. In this case, it would probably be best to take the starter assembly (incl, solenoid) where a pinion clearance check can be made. If the pinion clearance is incorrect, disassemble the solenoid and shift lever. Inspect these parts and replace as necessary.

Forcing snap-ring over the armature shaft

Snap-ring installation

(353 THRUST WAS WR

Brush Replacement

1. Disassemble the starter by following Steps 1 and 2 of the previous Drive Replace ment procedure.

2. Replace the brushes one at a time to avoid having to mark the wiring. For each brush: Remove the brush retaining screw and remove the old brush. Install the new brush in the same direction (krge end towards the end of the field frame). Position the wire con nector on the top of the brush, line up the holes and reinstall the screw. Make sure the screw is snug enough to ensure good contact.

3. Reassemble the starter according to Steps 10—14 of the previous procedure.

Solenoid Replacement

1. Remove the screw and washer from the

motor connector strap terminal.

Page 94

Year

1963- 64

1963

1964

1965

1966

1967- 68

1969

Engine Displacement (CM in.)

327 327 327 327 327 327 327 327 327 327 327 396 327 327 427

427 327 327 427 427 427

427®

350 350

Fuel

Delivery

System

4bbl

4bbl 4bbl

Fuel Inj

4bbl

Fuel Inj

4bbl 4bbl 4bbl 4bbl

Fuel Inj

4bbl 4bbl 4bbl 4bbl 4bbl 4 bbl 4bbl

4bbl 3-2 bbl 3-2 bbl

4 bbl

General Engine Specifications

Horsepower

(ffirpmn

250 @ 4400 350 @ 2800 4.00 x 3.25 10.5:1 300 @ 5000 360 @ 2800 4.00 x 3.25 10.5:1 340 @ 6000 344 @ 4000 4.00 X 3.25 11.25:1 360 @ 6000 352 @ 5000 4.00 x 3.25 11.0:1 365 @ 6200 360 @ 3600 4.00 x 3.25 11.0:1 375 @ 6200 350 @ 4000 4.00 x 3.25 11.0:1 250 @ 4400 350 @ 2800 4.00 x 3.25 10.5:1 300 @ 5000 360 @ 3200 4.00 x 3.25 10.5:1 350 @ 5800 360 @ 3800 4.00 x 3.25 11.0:1 375 @ 6200 350 @ 4000 4.00 x 3.25 11.0:1 365 @ 6200 350 @ 4600 4.00 x 3.25 11.0:1 425 @ 6400 41 5 @ 4000 4.094 x 3.76 11.0:1 300 @ 5000 360 @ 3200 4.00 x 3.25 10.5:1 350 @ 5800 360 @ 3600 4.00 x 3.25 11.0:1 390 @ 5200 460 @ 3600 4.25 x 3.76 10.25:1 425 @ 5600 460 @ 4000 4.25 x 3.76 11.0:1 300 @ 5000 360 @ 3400 4.00 x 3.25 10.0:1 350 @ 5800 360 @ 3600 4.00 x 3.25 11.0:1 390 @ 5400 460 @ 3600 4.25 x 3.76 10.25:1 400 @ 5400 460 @ 3600 4.25 x 3.76 10.25:1 435 @ 5800 460 @ 4000 4.25 X 3.76 11.0:1 430 @ 5200 450 @ 4400 4.25 x 3.76 12.0:1 300 @ 4800 380 @ 3200 4.00 x 3.48 10.25:1 350 @ 5600 380 @ 3200 4.00 x 3.48 11.0:1

Torque @ rpm

(ft. lbs.)«

Bore and

Stroke (in.)

Compres-

sion Ratio

OH Pressure @2000 rpm

45 45 45 45 45 45 45

45 45 45 45 45 45

45 60 60 45 45 65 65

65 65 45 45

z o

> z o

z o

Page 95

CO X

ENGINE AND ENGINE REBUILDING 89

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Page 96

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General Engine Specifications (cont.) g

m oo

Engine

Displace-

Year

1979

1980

1981

350

1982

350

1984

350

•Beginning 1972, horsepower and torque are SAE net figures. They are measured at the rear of the transmission with all accessories installed and operating. Since the figures vary when a given engine is installed in different models, some are representative rather than exact. ® Limited production engine L88, for special purposes © Not available in California <D Throttle body fuel injection

ment (cu In.)

350 350

305 350 350

Fuel Delivery System

4bbl 4bbl

4bbl 4bbl 4bbl

4bbl TBI® TBI®

Horsepower

@rpmB

195 @ 4000 225 @ 5200

180 @ 4200 190 @ 4400 230 @ 5200 1 90 @ 4200 200 @ 4200 205 @ 4300

Torque @ rpm

(fl. lbs.)e

285 @ 3200 270 @ 3600

255 @ 2000 280 @ 2400 275 @ 3600 280 @ 1600 285 @ 2800 290 @ 2800

Bore and

Stroke (in.)

4.000 x 3.480

3.736 x 3.480

4.000 x 3.480

Compression Ratio

8.2:1

8.9:1

8.5:1

9.0:1

8.2:1

9.0:1

Oil Pressure @2000 rpm

Page 97

Valve Specifications

Year

1963-64

1965-66

1967

1968

1969

1970

Engine Displacement (cu In.)

327 46 45 327 (High Pert)

327 327 (350 hp) 327 (fuel inj) 396 46 45 427 46 45 427 (425 hp) 327 (300 hp) 327 (350 hp) 427 (390, 400 hp) 427 (435 hp) 327 (exc 350 hp) 327 (350 hp) 427 (exc 435 hp) 427 (435 hp)

350 46 45 350 (350 hp) 427 (390, 400 hp) 427 (435 hp) 350 46 45 454 46 45 454®

46 46 46

Seal

Angle

(deg)

46 45

Face Angle (deg)

45 45

45 45 45 45 NA NA 45 45 45 45 45

45 45 45

Spring Test

Pressure (Ibs. 175 @ 1.26

175 @ 1.26 175 @ 1.26 175 @ 1.26 175 @ 1.26 315 @ 1.38 315 @ 1.38 315 @ 1.38 200 @ 1.25 200 @ 1.25

315 @ 1.38 198 @ 1.25 198 @ 1.25 315 @ 1.38 315 @ 1.38 200 @ 1.25 200 @ 1.25 312 @ 1.38 312 @ 1.38

80 @ 1.70 75 @ 1.88® 75 @ 1.88®

@ in.)

1.70

1.88

1.70

1.88

Spring

Installed

Height (in.)

1.66

1.88

1%2

1=/32

17/8

1^32

1% 1%

Stem to Guide

Clearance (in.)

Intake

0.0010-0.0027

0.0005-0.0024

0.0010-0.0027

0.0010-0.0037

0.0016-0.0033

0.0012-0.0029

0.0015-0.0032

0.0017-0.0027

0.0015-0.0032

0.0010-0.0027

0.0010-0.0047

Exft3EISt

0.3404-0.3417

0.3410-0.3417

0.3715-0.3722

0.3410-0.3417

0.3715-0.3722

0.3410-0.3417

0.3715-0.3722

0.3410-0.3417

0.3715-0.3722

0.3414

0.3718

Stem Diameter (In.)

Intake

0.3410-0.3417

0.3713-0.3720

0.3410-0.3417

0.3713-0.3720

0.3410-0.3417

0.3713-0.3722

0.3410-0.3417

0.3713-0.3722

Exhaust

0.3414

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Page 100

Crankshaft and Connecting Rod Specifications (cont.)

Year

1972

1973-74

1975-76 1977-84 305, 350

® Nos. 3, 4—2.7481 -2.7490; No. 5—2.7478- 2.7488 ® Nos. 2, 3, 4—2.4481 -2.4490; No. 5—2.4479-2.4488 ® No. 5—

2.7478-2.7488 ® No. 5 —0.0023- 0.0033; with auto, trans. No. 1 —0.001 9-0.0031 ® No. 5—

2.4479-2.4488 ® Nos. 2, 3, 4—0.001 3-0.0025; No. 5—0.001 9-0.0035 ® Nos. 2, 3, 4—

0.0006-0.001 8; No. 5 —0.0008-0.0023 ® Nos. 2, 3, 4 —2.7481 -2.7490; No. 5—2.7478-2.7488 ® Nos. 2, 3, 4—0.001 1 -

454 (425 hp) 350 350 (255 hp) 454 (270 hp) 350 454

350

Engine

Main Big

Journal Dia

2.7481-2.7490®

2.4484-2.4493®

2.7485-2.7494©

2.4484-2.4493®

2.4502©

2.7504®

2.4502®

All measurements are given in inches

Crankshaft

Main Big Oil

Clearance

0.0013-0.0025® 0.006-0.010

0.0008-0.0020® 0.002-0.006

0.0013-0.0025® 0.002-0.006

0.0013-0.0025® 0.006-0.010

0.0013-0.0025® 0.002-0.006

0.0007-0.0019® 0.006-0.010

0.0013-0.0025® 0.002-0.006

0.0008-0.0020® 0.002-0.006

Shaft

End-Play

Tlmist on No.

5 5 5 5 5 5 5 5

2.1985-2.1995

2.0990-2.1000

2.1990-2.2000

2.0990-2.1000

2.1990-2.2000

2.0990-2.1000

2.0988-2.0998

Journal

Diameter

Connecting Rod

Clearance

0.0009-0.0025

0.0013-0.0035

0.0009-0.0025

0.0013-0.0035

0.009-0.0025

0.0013-0.0035

Oil

z m

o m

Side

Clearance

0.019-0.025

0.008-0.014

0.015-0.021

0.008-0.014

0.015-0.021

0.008-0.014

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