Fiat 500L 1957 1973 User Manual

FIAT 500 1957-73

Workshop Manual

Autobooks

Models Covered

Fiat New 500

Fiat 500D Fiat 500F

Fiat 500L

Fiat and Autobianchi Giardiniera

1 :1

Description

1 :2

Engine removal (sedan—all versions)

1 :3

Engine removal (station wagon)

1 :4

Engine disassembly (sedan—all versions)

1 :5

Engine disassembly (station wagon)

1 :6

Cylinder head removal, servicing and replacement

1 :7

Timing gear overhaul

1 :8

Crankcase and cylinders

1:9

Piston assembly

1 :10

Connecting rods

1 :11

Crankshaft and main bearings

CHAPTER 1

THE ENGINE

1 :12

Flywheel and starter ring gear

1 :13

The oil pump

1 :14

Lubrication, oil filter, relief valve

1 :15

Valve timing

1 :16

Va lv e ste m to rocker clearance

1 :17

Engine assembly (sedan—all versions)

1 :18

Engine assembly (station wagon)

1 :19

Power plant mounting

1 :20

Adjustment of generator and fan belt drive

1 :21

Modifications

1 :22

Fault diagnosis

1 :1 Description

The 'New 500' two-cylinder aircooled engine operates on the four-stroke 'Otto Cycle' and is fitted directly to the transmission unit which incorporates the rear drive assembly as shown in FIG 1 :1 and FIG 1 : 2.

Wit h the power unit fitted at the rear several a dv an ta ge s are obtained including better load distribution to the wheels when the vehicle is loaded, elimination of propeller shaft reducing th e size o f centre tunnel and better use of available space.

The cylinder block comprises two cast iron cylinder

barrels w it h cooling fins. The bottom of the cylinders fit into machined seats i n the aluminium crankcase.

The aluminium crankcase carries eight studs on which are located the two cylinder barrels with the aluminium

cylinder head on th e top.

A tw o bush crankshaft of special cast iron is fitted into

the lower half of the crankcase. The crankshaft is

F500

provided with a counterweight and is hollow to allow for lubrication.

The steel connecting rods have thin wall bearing halves on the big-end, and bronze bushes in th e small-end. The offset piston pin is of steel and retained in the piston by two circlips.

Light alloy pistons are used and are of the taper-ovalshaped type w ith a maximum diameter at the base o f t he skirt, along an axis perpendicular to the piston pin. Pistons are fitted with four rings as follows, one compression at the top, two standard oil scraper rings and one side slotted oi l scraper ring.

The one-piece aluminium cylinder head is finned to provide a larger cooling surface and carries the inlet and exhaust manifolds.

The inlet passages merge into a single centralized

flange onto which is mounted the carburetter. The exhaust passages run almost parallel to the axis of the engine.

FIG 1:1 Left side view of the power plant to suit 500 Sedan

Moun ted on the top of the cylinder head is the overhead valve rocker mechanism t ha t is operated by a chain driven camshaft through tappets and vertical pushrods.

The carburetter is of the downdraft type fitted with a starting device that is controlled by a lever on the central floor tunnel. A pleated paper element air cleaner and silencer is fitted to the carburetter air intake. A mechanical diaphragm type fuel pump operated from the camshaft by a pushrod, supplies petrol to the carburetter fro m a fuel tank located at the front of the vehicle.

Engine lubrication is provided by a gear pump driven from the camshaft and mounted within the timing cover drawing oil from the engine sump. The oil is cleaned by a centrifugal filter situated at the rear e nd o f th e cr an ks ha ft and pressure is controlled by a valve mounted on the pump body. Crankcase ventilation is provided for through a rubber hose connected to the top of the rocker cover.

The engine is cooled by air from a centrifugal blower mounted on the generator shaft and housed in a specially designed cowling conveying air to and around the engine.

The air temperature is governed by a special thermostat fitted in the engine cowling.

FIG 1:2 Right side rear three-quarter view of the power plant for 500 Stati on Wagon

FIG 1:3 Engine section through crankshaft, pistons and valves

F500

FIG 1:4 Engine cross-section through a cylinder

The interior of the car can be heated by the engine warmed air being ducted into the front compartment and controlled by a lever on the heating system tunnel.

Engine ignition is by a battery, ignition coil and distributor which is driven by a gear on the camshaft. The engine is started by an electric starter motor which is mounted on the gearbox casing and is controlled by a lever located behind the gearchange lever.

The complete power unit is mounted by a spring support at the centre of the rear body crossmember and by two rubber pads mounted laterally to the gearbox.

1 :2 Engine removal (sedan—all versions)

To remove the engine from the car proceed as follows: 1

Raise the rear of the car and place on firmly based

stands placed under sui table brackets on the u nderside

of the body.

Disconnect the battery positive terminal clamp from the

battery terminal post. Release the clip securing the main

petrol pipe to the tank sender unit and ease the pipe from the unit. Drain the oil from the engine sump into a suitably sized container. Disconnect the rear number plate light wire (see

FIG 1 :6). Release the engine compartment lid check strap from its slot and separate th e li d f r om th e b o dy by sliding the hinge apart. Remove the cables attached to the ignition coil, also

to the generator and the starter motor. Remove the

starter motor control tie rod.

Release the oi l pressure indicator cable, the main petrol pipeline at the pump, the accelerator and s tarting device controls.

Remove the two hoses of the heating and cooling

system which are the input hose to t he blower and the hose f o r t h e car heating system. Release and lift out the engine apron. Remove the starter motor mounting bolts and carefully lift away the motor.

Usin g a garage hydraulic jack w i t h suitable cradle (see

FIG 1:7) or a rope sling relieve the engine weight from its mountings. Remove the nuts securing the gearbox to the engine and the flywheel protection

apron.

Remove the bolts fixing the elastic support to the cross-

member. Remove the rear crossmember mou nting nuts

noting that the engine earth cable is held by one

mounting nut and lift away the crossmember.

Carefully ease the engine away from the gearbox

ensuring that there is no strain placed on the clutch shaft. Lower the engine to the flo or taking care that no weight is allowed on any of the attachments.

1 :3 Engine removal (station wagon)

To remove the engine from the station wagon proceed

as follows: 1 Raise t h e rear of t h e vehicle and place on firmly based

stands placed under suitable brackets on the underside

of the body.

2 Disconnect the battery positive terminal clamp from

the battery terminal post. Release the clip securing the

main petrol pipe to the tank sender unit and ease the pipe from the unit. Drain the oi l from the engine sump

into a clean dry container of suitable size.

3 Ho ld th e rear d o or open an d secure using string to stop

it swinging to the closed position. Secure the luggage

compartment floor panel in its upright position.

FIG 1:5 120.000 engine assembly: cross-section view

through a cylinder

4 Remove the cables attached to the ignition coil, also

to the generator and starter motor. Remove the starter

motor control tie rod. Release th e oil pressure i ndi cat or cable, the main petrol pipe line at the pump, the accelerator and starting device controls. Disconnect the air filter housing.

5 Remove the hose connecting the car heating system

to the engine cowling. Disconnect the clip holding the

air pipe to the blower and carefully disconnect the pipe

from the blower cowling. Remove the starter motor

moun ting bolts and carefully lift away the motor.

F500

NUMBER PLATE LAMP CABLE JUNCTION

NUMBER PLATE LAMP CABLE

LID LOCKING

HOOK

LID CHECK ARM

FIG 1:6 Engine co mpa rtm ent lid open

that rear air ducting panels are not strained or the mating faces damaged.

8 Carefully ease the engine away from the gearbox ensur-

ing that there is no strain placed on the clutch shaft.

Lower the engine to the floor taking care that no weight

is allowed on any of the attachments.

1 :4 Engine disassembly (sedan—all versions)

To dismantle the engine proceed as follows:

1 Remove the exhaust silencer by releasing the two

collars for at tachment to the engine and the tw o connections for the exhaust pipe. It will be noted that there is one exhaust pipe connection on either side of the cylinder head.

2 Pla c e the engine on a firm wooden top bench. Remove

the tw o tappet cover retaining nuts and washers and

lift away the cover. Remove the connection for cooling air delivery to the sump cooling ducts at the side of the sump.

3 Remove the air cleaner after first releasing the two

bolts on the air cowling and the two nuts for the air elbow connection to the carburetter.

4 Remove the generator drive belt by releasing the

three nuts so splitting the semi-pulley. Lift away the drive belt.

5 Remove all the bolts securing the air conveyor

ducting to the cylinder head, to the crankcase and also to the engine co wling assembly opposite to the air conveyor. Release the accelerator control tie rod and carefully lift away the air conveyor assembly complete with the generator after first removing the clamp fixing the generator to the crankcase.

CROSS MEMBER ARR.2O74.

FIG 1 :7 Engine removal using the jack with crossmember Arr.2074

6 Using a garage hydraulic jack with a suitable cradle

relieve the engine weight from its mountings. Remove the nuts securing the gearbox to the engine.

7 Remove the nuts securing the rear bumper blade and

panel to the body. Note that the engine earth cable is held by one mounting nut. Carefully dismantle the engine elastic mounting or release th e bracket from the engine rear cover by removing the two nuts and washers. Lift away the rear panel assembly carefully making sure

FIG 1:8 Engine components: crankcase, cylinder head,

timing sprockets cover

6 Release the ignition distributor support retaining nut

and lift away the distributor together wi t h its support.

7 Remove all the mounting bolts of the engine cooling

co wl in g and lif t away the assembly. Release the t wo carburetter retaining nuts and carefully remove the

carburetter together wi th its drip tray.

8 Lift away the valve rocker assembly having first

released t he two retaining nuts together with the plain

washers and lock washers. Carefully lift out the valve

rocker pushrods noting their relevant positions.

9 Slacken the four central cylinder head cap nuts and

the four conventional nuts in the order, s hown in

FIG 1 :44 or 1 :46. Lift the cylinder head from the

barrels. If di ffi cul ty is experienced it is essential to use

Fiat tool A.40014 or a similar drilled plate, otherwise serious damage could be caused if other means are used (see FIG 1:9).

10 Remove the four pushrod sleeves and the casing

containing the oil ducting to the overhead valve gear.

11 Remove the fuel pump retaining nuts and washers

and lif t away the pump. Carefully pull out the pump control pushrod from the crankcase.

12 Remove the six screws holding the centrifugal oil filter

pulley cover and lift away the cover. Remove the centrifugal filter mounting flange by unscrewing the crankshaft central bolt. Also remove the timing cover containing the oil pump gears and the oil pressure regulating valve. Note the position of the nuts, toothed and plain

13 Release the four camshaft sprocket retaining bolts and

lift away the sprocket and timing chain. Using Fiat pulley A.46020 or a large universal two-leg puller as shown in FIG 1 :10 remove the crankshaft sprocket and its body.

14 Carefully lift out th e rocker pushrod tappets making a

note of their location and gently pull out the camshaft making sure the front bearing bore is not damaged by the cam lobes or distributor drive gear.

15 Mark the flywheel and crankshaft to ensure correct

reassembly and release the six flywheel retaining bolts

together with the lockwashers and lift away the fly-

wheel.

16 Using Fiat tool A.60156 on the two central studs, lock

the two cylinder barrels in place as shown in FIG 1 :11 .

washers for correct reassembly.

PULLER A .46020

FIG 1 :10 Removing crankshaft sprocket with puller A.46020

TOOL A.60156

TOOL A. 40014

FIG 1 :9 Tool A.40014 for cylinder head removal

F500

FIG 1:11 Cylinder hold-down tool A.601 56

17 Turn the engine upside do wn ensuring that no weight

is placed on the studs and remove the oil sump and the oil suction scoop.

18 Mark the connecting rods and end caps to ensure

correct reassembly and remove the end caps. Place the engine on its side and remove the cylinder barrels clamp. Ensure that the studs are clean and carefully slide off the connecting rod-piston-cylinder assemblies from the crankcase.

19 Remove the six screws holding the rear main bearing

housing to the crankcase and lift away the housing.

Remove th e six screws holding the front main bearing

housing to the crankcase and lift away the housing.

20 Carefully ease the crankshaft from the crankcase

moving it diagonally to assist withdrawal.

STUD REMOVAL PULLER 40010

FIG 1 :12 Removal of stud from crankcase by puller A.40010

.SPACER AND CONNECTION

FOR ROCKER SHAFT

LUBRICATION TUBE

OILVAPOR .VENT PIPE

CASINGS FOR PUSHRODS

(AND OIL RETURN

TO CRANKCASE

FIG 1 :13 Engine without blower cowling and cylinder head cover

4 Remove all t h e b o lt s se curing the air conveyor ducting

to the cylinder head and to the crankcase, carefully separate the panels and l if t aw ay th e separate panels ensuring no damage is caused to t he mating faces.

5 Release the ignition distributor retaining bolt and lift

away the distributor.

6 Remove the fuel pump retaining bolts and also the

three fuel pipe retaining clips and lift away the fuel pump assembly together with the insulator, gaskets and control rod.

7 Release the t wo valve rocker retaining nuts, note the

order of assembly of washers and ease away the rocker

shaft assembly from the top of the cylinder head.

Carefully lift out the valve rocker pushrods noting

their relevent posit ions for correct reassembly.

8 Slacken the four cylinder head cap nuts and the four

conventional nuts in the order shown in FIG 1 : 46 . Lift the cylinder head away from the barrels. If d ifficulty is experienced it is essential to use Fiat tool A.40014 or a similar drilled plate as shown in FIG 1 :9, otherwise serious damage could be caused if other means are used.

9 Remove the four pushrod sleeves and t he casing con-

taining the oil ducting to the overhead valve gear.

10 Remove the six screws holding the centrifugal oil filter

pulley cover and lift away the cover. Remove the

centrifugal filter mounting flange by unscrewing the crankshaft central bolt. Also remove the timing cover from the rear of the crankcase. Note carefully the position of the nuts, toothed and plain washers for correct reassembly.

11 Release the four camshaft sprocket retaining bolts

and lift away the sprocket and timing chain. Using

Fiat puller A.46020 or a large universal two-leg puller as shown in FIG 1 :10 remove the crankshaft sprocket and its key

12 Carefully lift out the rocker pushrod tappets making a

note of their location and gently pull out the camshaft making sure that the front bearing bore is not damaged by the cam lobes.

21 To ensure no damage occurs to the long cylinder

barrel mounting studs these may be removed using

Fiat puller A.40010 or a universal stud removal as

shown in FIG 1 :12.

1 :5 Engine disassembly (station wagon)

To dismantle the engine proceed as follows:

1 Remove the exhaust silencer and manifold by releasing

the four nuts holding the two flanges from the cylinder head. Also disconnect the two silencer mounting brackets and lift away the exhaust system (see

FIG 1 : 2 ).

2 Pla c e the engine on a firm wooden top bench. Release

the clip holding the tappet cover and lift away together wi t h the drip tray. Disconnect the fuel line and throttle

linkage at the carburetter and carefully lift away the carburetter together with its insulator joint and gaskets.

3 Remove the generator drive belt by releasing the three

nuts so splitting the semi-pulley. Lift away the drive

belt.

TOOL A. 60084

FIG 1 :14 Tool A.60084 for valve and valve spring removal

13 Remove all the bolts and washers joining the sump

casting to the crankcase making a special note of the location of bolts of different lengths.

14 Mark the flywheel and crankshaft to ensure correct

reassembly and release the six flywheel retaining bolts together with the lockwashers and lift away the fly-

wheel.

15 Using Fiat tool A.60156 on the two central studs, lock

the tw o cylinder barrels in place (see FIG 1 :11).

16 Turn the engine upside down ensuring that no weight

is placed on the studs.

17 Mark the connecting rods and end caps to ensure cor-

rect reassembly and remove the end caps. Place the engine on its side and remove the cylinder barrels clamp. Ensure th at th e studs are clean and carefully slide off the connecting rod-piston-cylinder assemblies from the crankcase.

18 Remove the six screws holding the rear bearing hous-

ing to the crankcase and lift away the housing. Remove the six screws holding the front main bearing housing to the crankcase and l ift away i ts housing.

19 Carefully ease the crankshaft from the crankcase

moving it diagonally to assist wi t hd ra w al .

20 To ensure no damage occurs to the long cylinder

barrel mounting studs these may be removed using

Fiat puller A.40010 or a universal stud remover as

shown in FIG 1 :12.

WIRE BRUSH A.11417 / BIS

FIG 1:16 Cleaning valve guides

1 :6 Cylinder head removal, servicing and replacement

Description:

The aluminium cylinder head is finned to increase the

cooling surface. Through bolts secure the head and the

tw o cylinders to the crankcase. The valves are controlled

by a camshaft through tappets, pushrods and rockers. The connection between t he head and the crankcase is via five

sleeves mounted directly between the head and crankcase,

and these accommodate the pushrods, lubricating oil and passage f or th e crankcase gases. The cylinder head has

modified for the 110 F and later 120 engines as

been they now incorporate a heater safety device as described in Section 4:4.

TOOL A. 60153-

WITH PILOT BUSH

FIG 1 :17 Installing a valve guide using Tool A.60153 provided with pilot bush

F500

FIG 1:15 Cylinder head

Removal of cylinder head:

The cylinder head should be removed whenever the valves req ui re a t t e nti o n or t h e engine to be decarbonized. To remove the cylinder head proceed as fol low s:

1 Remove the air cleaner, carburetter, rocker cover and the

screws securing the blower conveyor to the cylinder

INTAKE

EXHAUST

INTAKE

FIG 1 :18 Main specifications of intake and exhaust valves and valves guides (dimensions in mm)

EXHAUST

head. Disconnect the two side exhaust manifolds. Note the spark plug HT cables locations and dis-

connect from spark plugs.

2 Remove the rocker shaft pedestal- and lift away the

rocker gear. Extract the pushrods, making a careful note of their location. Remove th e cylinder head hold

down nuts in the order shown in FIG 1 :44 and using a

puller as shown in FIG 1 :9 lift off the head.

Dismantling the cylinder head:

1 Using Fiat valve spring compressor A.60084 or a uni-

versal spring compressor depress the valve spring as shown in FIG 1 :14 and lift out the cotters. Release the compressor and withdraw the lock cone, oil shield

(inlet valve only) upper spring cup, valve spring and lower spring cup. Withdraw the valve from the under-

side of the head.

2 Dismantle the remaining three valve assemblies as

detailed above ensuring that all parts are kept in sets for cor rect reassembly.

Inspection and servicing of the cylinder head : 1 Remove all carbon deposits from the combustion

chambers and valve ports using a rotary wire brush or a set of scrapers.

2 Thoroughly clean the cylinder head and to test for dis-

tortion lightly coat the machined faces with 'Engineers

Blue' or lamp

black and place the cylinder head on a surface plate. Carefully slide to and fro and any streaks left behind will indicate a distorted surface. A distorted

head will not make a gas-tight seal with the cylinders and must be entrusted to an expert for correction or, in severe cases, renewed.

3 Carefully clean the valve guides as shown in FIG 1:16

using Fiat guide brush A.11417 bis. Should the guides

be worn then they should be removed using a press and a suitable sized dr ift . The gu ide s are press fitted with a pinch fit of .00134 to .00244 inch. To install the guides use Fiat tool A.601 53 as shown in FIG 1 :17. As the guides have no stop ring during the press fitting, the depth of insertion is determined by the Fiat tool. If the too l is not available take the necessary depth measure-

ments before the ol d guides are removed. The normal fit clearance between valve stem and guide is .00087 to .00217 inch with a maximum wear limit of .0059 inch. To check this see FIG 1:18.

4 The valve seats should always be reconditioned after

decarbonization. It is suggested that this operation be left to a local service station with valve seat cutting equipment. The valve seat angle for both inlet and exhaust valves is 45° ± 5'.

5 Inspect the valves fo r soundness or distortion and if the

clearance between guide and stem is within the manufacturers wear tolerance of .0049 inch the valve may

be cleaned using a wire brush and the seating face ground to an angle of 45°30' ± 5'. This again should

be left to the local service station.

Valve springs:

Thoroughly clean the valve springs of oil deposit and

inspect for cracks. It is advisable to check the free spring height and if this dimension differs from the original height, details of which are given in Technical Data, the spring must be renewed. Any decrease in length indicates that the spring has weakened.

Reassembly o f t h e cylinder head:

Reassembly is the reverse procedure to dismantling. During assembly utmost cleanliness must be observed as any abrasive material could find its way to the pistons and cylinder bores causing unnecessary wear. Check that the cylinder barrel mating face is clean to ensure correct

gasket sealing.

Cylinder head installation:

To refit the cylinder head proceed as follows:

Place a new cylinder head joint on the cleaned faces of

the cylinder barrels. Insert the rocker pushrod and lubrication pipe sleeves together with the relevant gaskets and rings.

Fit the washers and nuts to the studs and tighten to

fingertight.

Tighten the nuts in the order shown in FIG 1 :44 and

FIG 1 : 4 6 to a torque wrench setting of 18.1 Ibft. Reset

the torque wrench to a new setting of 23.9 Ibft and tighten the nuts once more in th e recommended order.

Replace th e pushrods in the correct order.

Refit the rocker shaft ensuring correct location of the lubrication tube to the rocker shaft and replace the plain and lockwashers. Tighten the nuts to a torque

wrench setting of 15.2 Ibft. Reset th e tappet to rocker

clearance adjustment.

Connect the two exhaust side manifolds to the cylinder head. Using new gasket refit the spark plugs and HT cables. Replace t he rocker cover fitted with a new cork gasket and blower conveyor to the cylinder head securing screws. Refit t he carburetter and reconnect its

fuel line and controls. Refit the air cleaner and elbow

and connect the rocker cover breather pipe (if fitted).

FIG 1:19 Camshaft. The arrow points to the lube oil outlet port

1 :7 Timing gear overhaul Camshaft:

The cast iron camshaft is located in the crankcase and is

supported at either end in sets machined directly in the

crankcase. No bushes are used. The camshaft is driven by a chain from the crankshaft at half engine speed and operates the overhead valves through tappets, pushrods

and rockers (see

During engine overhaul the camshaft journals and cam faces should be free of score marks or s ig ns of seizure a n d have a bright mirror finish.

The distributor drive gear should be inspected for tooth wear which if excessive means t h a t t he ca mshaft must be replaced.

Tappets:

The tappets should be inspected for signs of seizure or excessive wear. The end surface that is in contact with the camshaft should be smooth without signs of excessive wear. Any slight scratches or indentations may be removed using a very fine oil stone.

Pushrods and sleeves:

The pushrods operate in special axially resilient sleeves that are compressed on assembly between the cylinder head and the crankcase. It is through these sleeves tha t the engine sump is vented also through which the oil returning from the cylinder head passes.

Two rubber O-ring seals are fitted to each sleeve to ensure an oil tight seal between the cylinder head and crankcase. The sleeves should be checked for distortion and exact equal length and when refitting new seals must always be fitted.

The pushrods should be checked for straightness and

the two ends that contact the rocker setscrew and the

FIG

:20).

FIG 1:20 Valve, pushrod and tappet assembly

Key t o Fiq

3 Oil shield (f or intake valves only) 4 Snap ring 5 Rocker 6 Upper spring cup 7 Valve spring 8 Lower spring cup 9 Pushrod 10 Tappet 11 Oil seal ring 12 Pushrod sleeve 13 Seal ring

tappet seat must not show any signs of roughness or excessive wear.

Rocker and rocker shaft:

During valve gear overhauls the clearance between the rocker shaft bore and the rocker must be checked. The maximum permissable wear between these two parts is .0059 inch. It is recommended t hat the part which is most worn be renewed, or in extreme cases bo th parts.

1 :8 Crankcase and cylinders

The crankcase is an aluminium casting suitably ribbed to ensure correct air cooling. The main bear ing and camshaft bearing bores are machined as also are the tappet

:20

1 Intake valve 2 Upper c up lock

F500

FIG 1:21 Finned cylinder. Letter A stamped on cylinder indicates the cla s s to which cylinder belongs, as referred to it s inside diameter

It is essential tha t the diameter measurements are taken at two different heights in the cylinder bore along both the longitudinal and transverse axles as sh o w n i n FIG 1 :22. It is recommended that to zero the internal micrometer

Fiat ring gauge C.672 is used (see FIG 1 :2 3).

If bore wear or ovality is between .0059 and .0079 inch the cylinder bore may be honed. Should however the wear limit of .0079 inch be exceeded the n the bores must be recut.

Honing or reboring cylinder bores:

This operation should bring the bore size to correspond to th e oversize piston sizes in order to obtain the correct clearance between the piston and cylinder. These

limits are given in Technical Data. It will be observed that the cylinders are divided into three classes depending on the bore diameter. The classes are identified by the letters 'A',

and 'C , one of which will be stamped on the mating face with t h e cylinder head as shown in FIG 1 :21. Pistons are divided into three classes to correspond with the cylinder bore sizes. Naturally the piston and bore must belong to the same class. The m aximum available piston oversize is .0236 inch.

Pistons and rin gs for the Model 500 sports engine are not available in oversize dimensions so if the cylinder bore diameter is above the maximum wear limit new parts must be fitted.

CLASS LETTER

FIG 1 :22 Cylinder measurement points

seats, gearbox companion flange and timing gear cover mounting flange.

The cast iron cylinders are finned radially to increase the cooling air surface and are located symmetrically on the crankcase, each being held by four studs. The cylinders are installed by sliding into the crankcase bores and finally held in place by the cylinder head (see FIGS 1 :8 and

1 :21).

Inspect the cylinder bores for score marks, wear and any other defects or damage. The clearance between the piston maximum diameter and the cylinder bore should be checked to ensure tha t i t i s within the maximum wear limit

of .0059 inch.

Checking cylinder height:

The cylinder height must be checked between the seating face on the crankcase and the top surface and this dimension should be 3.5433 ±0006 inch.

If this dimension is less than specified the cylinder must be renewed to prevent possible carbon deposits on the piston crown and underside of combustion chamber causing the piston to strike the cylinder head (see

FIG 1 :24).

DIAL GAUGE C 687

RING GAUGE C. 67 2

FIG 1 :23 Checking cylinder diameter by dial gauge C.687 brought to zero with ring gauge C.672

Insert a .0079 ± .00197 inch thick oil paper gasket between the crankcase and cylinder bottom face and a .0236 to .0275 inch thick graphitized asbestos gasket between the cylinder and cylinder head. The compression of th e gaskets on assembly will eliminate any very small differences between the two mating surfaces.

Inspection of tappet seats:

The tappet seats should be checked for scoring and correct clearance which must not exceed .00315 inch . Should the clearance be greater than the maximum specified the seating may be reamed to oversize dimen sions as detailed in Technical Data. Tappets are available in .00197 and .00394 inch diameter oversize.

1 :9 Piston assembly

Inspection:

Before inspection the pistons must be thoroughly cleaned and the ring grooves and piston head decarbonized. Check f or deep score marks an d si gns of distortion

or fracture especially around the skirt and piston pin areas.

Using a feeler gauge ensure t h at th e piston clearances in

the bore do not exceed a maximum of .0059 inch for the

Model 500 engine and .0079 inch for the Model 500

sports engine (see FIG 1 :2 5) . The measurements should

be taken at the bottom of the s k ir t and square to the piston pin axis.

Should the clearance be greater than the maximum permissible, the cylinders may be rebored and oversize pistons fitted to m

atch them. Pistons are supplied in the

following oversizes, .0079, .0157 and .0236 inch. It

should be noted that oversize pistons and rings are not available for th e Model 500 sports engine so if the piston

to cylinder wall clearance is greater than the permissible

maximum limit the cylinder and piston assembly must be renewed.

The piston ring to groove clearance must be checked as

shown in FIG 1 :26 and th e ring gap w hen fitted as in

FIG 1 :27. In both cases the readings should be

compared wi th the piston data. Piston rings are available in the same oversize classes as the pistons. When installing piston rings the gap should be placed opposite to the piston expansion stops. Ensure t ha t t h e ring gaps are scattered and not in a line.

FEELER GAUGE C.316

FIG 1:25 Using feeler gauge C.316 t o check piston-tocylinder wa ll clearance

FIG 1:24 Checking cylinder head mating face f or level

Out-of-true should not exceed .00315 i nch

F500

FIG 1 :26 Checking piston ring-to-land clearance

Check th at the fit be tw ee n th e piston pin and boss is a pinch fit. If excessive clearance is found the boss may be reamed and a .0079 inch diameter oversize piston pin fitted. The pin to bore pinch fit must be between .0000 to .0039 inch. At all times the pins should be installed only after the piston has been heated in hot wat er to a temperature of 80°C. Upon reassembly of the piston to the engine the expansion slot must be placed facing the camshaft.

Reassembly of piston:

The installation of the piston and connecting rod should

be carried out on a clean workbench as shown in

PISTON RING

FEELER GAUGE

Checking ring gap (ring in cylinder)FIG 1 :27

Place a piece of 'Plastigage type PG-1' along the full

width of the bearing insert along the crankshaft

longitudinal axis (see FIG 1 :30). Refit the bearing cap and tighten the nuts to a torque wrench setting of

23.9 Ib ft. Remove the bearing cap and upon inspection the 'Plastigage' will be found to have adhered to either the crankpin or bearing insert and will have developed a

rectangular section. To determine the actual clearance

between the crankpin and bearing insert compare the width of the flattened 'Plastigage' at its widest point with the graduations on the envelope as shown in

FIG 1 :31.

If the clearance indicated is within the recommended

PISTON INSTALLER

A. 60154

FIG 1 :28.

A universal piston ring compressor should be

used to keep the rings ti ght i n their grooves. The correct matching of the piston and connecting rod is described in a later section of this chapter.

1 :10 Connecting rods Checking rod bearing inserts and crankpin jour-

nals:

The big-end bearing halves are of the babbit lined thin wall type and must not be modified in any way. Should score marks or excessive wear be evident the bearing inserts must be renewed. It is recommended that if the bearing inserts are to be renewed due to wear the cra nkpins should be measured to see if regrinding is required.

Before regrinding the crankpins they should be measured at the maximum p oin t of wear to determine the class of b earing undersize to be fitted after regrinding the crankpins. Undersize bearing halves are available in the following sizes .01, .02, .03 and .04 inch. The correct bearing crankpin clearance is .00043 to .00240 inch and

must be checked as detailed in the following section.

Checking rod bearing insert to crankpin journal clearance:

Before the crankshaft is installed into the engine after overhaul the clearance must be checked to ensure that it is within the manufacturers recommended limits. To check the clearance proceed as follows:

Lubricate the crankpin and bearing inserts and install

the connecting rod together with its bearing halves on

the crankpin. Tighten the cap nuts to a torque wrench

setting of 23.9 Ibft.

Rotate the connecting rod around the crankshaft journal several times to seat the bearing insert correctly. Remove the bearing end cap and carefully wipe away all traces of the lubricant.

FIG 1 :28

FIG 1 :29 Connecting rod components

Piston installer A.60154

tolerance range of .00043 to .00240 inch or less than

.0059 inch th e bearing inserts may be used again without any need for regrinding. Should however the clearance be greater th a n .0059 i nch the inserts must be renewed, using undersize inserts if the crankpin journals have bee n reground.

It should be observed t h a t 'Plastigage PG-1' is suitable for measuring clearances up to .0030 inch so that if carrying out 3 above produces no flattening of the

'Plastigage' the procedure must be repeated using

'Plastigage PR-1' which enables clearances up to

.0060 inch to be measured.

PISTON SLOT

CAMSHAFT

REVOLUTION

DIRECTION

CRANKSHAFT

CON RO D

FIG 1:30 'Plastigage' position for bearing insert-to-

crankpin journal clearance in spectio n

GRADUATION SCALE

CALIBRATED STRIP

CON ROD

BEARING CAP

BEARING INSERT

BEARING .INSERT

CONNECTING ROD NUMBER

FIG 1:32 Connecting rod-piston assembly installation

on engine

Installation of connecting rod bearing inserts:

During reassembly of the big-end bearing inserts the parts must be thoroughly cleaned and then to reassemble proceed as follows: 1

Ensure t he bearing half to connecting rod surfaces are

perfectly smooth and free of score marks. Under no circumstances may the bearing surface be reworked.

Check th at th e bearing half inserts are properly seated,

with the locating lugs fitting into their slots: this is

essential to obtain

As the circumference of the bearing half is greater t h a n

the seats in connecting rod and cap the bearing must be fitted so that the projection at each end of the bearing half is equal.

Thoroughly lubricate all parts and tighten the end cap nuts to a torque wrench setting of 23.9 Ib ft.

correct bearing clearance.

CLEARANCE

READING

CON ROD BEARING CAP

FIG 1 :31 Checking bearing insert-to-crankpin journal clearance by comparing width of flattened 'Plastigage'

F500

CALIBRATED

STRIP

Little end bushing:

The small end bush must be a firm fitting in the con-

necting rod and show no signs of deep scoring, scuffi ng,

ovality or excessive wear.

Should it be considered necessary, the bush may be reamed using a Fiat e x panding reamer U.0307 so that the bush internal diameter permits an oversize piston pin to be fitted with a clearance of .00020 to .00063 inch.

To fit a replacement bush proceed as follows:

Firmly hol d the connecting rod between soft faces in a

vice in such a way that it will not bend when working

on the small-end and using a suitably si zed drift, remove

the old bush.

Use Fiat tool A.60155 or a suitably sized drift and care-

fully install the new bush which must be an interference fit of between .0011 to .0036 inch. A small slo t must b e cu t in the bush to correspond w i t h

the groove machined at the to p of the connecting rod

so ensuring good lubrication between the bush and

piston pin.

FIG 1:33 Checking crankshaft land-to-connecting rod shoulder clearance

Upo n reassembly t he connecting rod cap nuts must be

tightened to a torque wrench setting of 23.9 Ib ft .

1:11 Crankshaft and main bearings

The special cast iron crankshaft is hollow to allow for the pa s s a g e o f lubrication oil. It is supported at its ends and is provided with two cranks and a central cou nterweight.

The crankshaft plays an important part in the operation of

the lu bri ca ti on system as i ts cavity provides a passage f o r the oil flowing from the centrifugal filter.

Before inspecting the crankshaft thoroughly clean the internal passage and drillings as well as the exterior and then proceed as follows:

Carefully inspect the crankshaft for minute cracks espe-

cially where there is a change in section. Should there

be any doubt always consult the official agents for

further advice.

Inspect the journals and crankpins. Should score marks

or ovality exist on the journals or crankpins they must

be reground and new undersize bearings fitted. Undersize main bearings are obtainable in the sizes

.0079, .0157, .0236, .0314, .0394 inch ready fitted in

supports.

Undersize connecting rod bearings are obtainable in the sizes .01, .02, .03 and .04 inch. The crank should be reground to match the appropriate bearing undersize.

The clearance between the main bearing to journal should be .00079 to .00256 inch and the connecting rod bearing half to crankpin between .00043 to

.0024 inch.

FIG 1:34 Engine f ro n t end without flywheel

Usi ng an e xpa ndi ng reamer or Fiat reamer U.0307 ease out the internal diameter of the bush to between .7874

to .7876 inch so that a standard piston may be fitted.

Piston-connecting rod assembly:

To assemble the piston to the connecting rod fit the connecting rod to the piston so that the cylinder iden tif ic ati on number which is stamped on the connecting rod stem and cap faces the expansion slot side in the piston as shown in FIG 1 :32.

Lubricate the piston with engine oil, compress the piston rings i nto their grooves and insert t he piston con-

necting rod assembly into the cylinder barrel with the identification numbers facing to the side opposite to the

camshaft as sh o w n i n FIG 1 :32.

If one or both connecting rods have been renewed th e

new connecting rod cap and body must be stamped wi th

the cylinder identification number. The figures should be

stamped as show n in FIG 1 :32.

CRANKSHAFT SUPPORTING MEMBER

(Camshaft end)

MAIN BEARING

FIG 1:35 Camshaft end crankshaft supporting member and bearing assembly, and spare main bearing

After the crankshaft has been reground it is important

that all traces of swarf a re removed by constant washing

and then drying wi th a no n-fluffy rag. The clearance between the main bearings and journals

must be checked before in stal ling th e crankshaft in the engine. It should also serve as a recheck after the

crankshaft has been reground.

Measure the maximum main bearing internal diameter and the minimum journal diameter using

accurate measuring equipment. The clearance must not

exceed .0039 inch otherwise the journals must be reground and undersize bearings fitted.

Undersize bearings with .0394 inch stock on the internal diameter are also supplied unmounted. They must be press fitted in the supports, the recommended interference fit being .00039 to .00197 inch. After pre s s ing the bearin g into the support, a hole is drilled in

the bearing in line with the location dowel hole in the

support. The hole is finished wit h a suitable expanding reamer, su ch as Fiat U.0334, and the dowel pressed i n ,

noting that the hollow dowel fits in the flywheel end support.

The next stage is to heat the assembly in an oven or oil bath for a period of one hour at 150°C (302°F). When the assembly has cooled to room temperature,

the b ea rin g is reamed in a l ath e to mat ch the crankshaft journal size.

Crankshaft oil seals:

Tw o inner spring rubber oil seals are located, one in a

special seat in the timing gear cover and the other in the flywheel end of the crankshaft support and provide oil tightness. These seals are s h ow n i n FIGS 1 :3 and 1 :34.

Whenever the engine is dismantled for overhaul these

seals should be carefully inspected fo r correct seating and

that the inner seal surface is not worn and that the contact area i s perfect b oth on the crankshaft and on the fan and generator drive pulley hub.

Clutch shaft pilot bushing:

A self-lubricating bronze bush is fitted in the end of the

crankshaft as s h o wn in FIG 1 : 34 and provides a bearing for the clutch shaft. Should the bush be worn use Fiat

puller A.40006/1 /2 to remove the worn bush. A new bush

should be fitted using a suitably sized drift.

1:12 Flywheel and starter ring gear

The flywheel should be inspected for wear at the clutch

driven plate contact area. It should be flat and have a

smooth finish.

The ring gear teeth should be cheeked for damage which if evident, the ring gear must be replaced. To facilitate the fitting of a new ring gear on the flywheel, the new

ring gear should be heated in an oi l ba th to a temperature

of 80°C ( 176°F). Using a press gently ease t h e

expanded

ring gear over the flywheel and press fully home.

1:13 The oil pump Sedan :

A helical-spur gear type oil pump is driven by the cam-

shaft th rough a front dog drive coupling. The gears are

FIG 1:36 Engine lubrication diagram

Key to Fig

Rocker shaft

Ducts, cylinder head oil drain

Oil pressure relief valve

to centrifugal filter

with central oil gallery

indicator sending unit

:36

Centrifugal oil fitter

Sump cooling air conveyor

Oil filler with vent valve

Line, oil delivery to rocker shaft

Gear pump

Oil pump intake screen filter

Level indicator rod

13 L ow oil pressure

8 Oil duct

Crankshaft

located in a special housing in the timing gear cover and

held in place by a cover plate. The oil pressure relief valve

is mounted on the drive gear shaft guide.

A pump suction scoop fitted with a filter screen is secured in the crankcase and connects to a duct in the timing gear case a s s h o wn i n FIG 1 :36.

Pump removal and reassembly:

To remove the pump from the engine proceed as follows:

Remove th e engine rear central support from the timing

gear casing. Remove the filter cover pulley and lift

away the drive belt.

Release the hollow screw attaching the slinger and the

mounting flange of the filter on the crankshaft. Also release the nuts fixing the timing gear cover to the crankcase.

Remove the timing gear cover together with the oil

pump assembly and the pressure relief valve.

Lift out the oil pump suction scoop with the filter

screen attached from the sump. 5

Reassembly of the pump to the engine is the reverse procedure to d ismantling.

F500

FIG 1:37 Lubrication diagram of engine 120.000

Key to Fig 1:37 1 Oil dipstick 2 Oil filler with vent valve 3 Centrifugal oil filter

4 Crankshaft, with central oil gallery 5 Low oil pressure indicator sending unit 6 Oil pressure relief valve 7 Gear pump 8 Camshaft, with central oil gallery 9 Oil suction filter from sump 10 Oil sump drain plug 11 Oil delivery line to rocker shaft 12 Rocker shaft 13 Head cover

Inspect the filter screen on t he end o f the pu mp suction

Pump dismantling, inspection and reassembly:

Remove th e lock ring and withdraw the pressure relief valve and sp rin g. Remove the o il pump cover plate and ease o ut t he gears and shaft.

Thor oughly clean all the parts and blow clean using a compressed air jet. Inspect the timing gear cover for cracks or distortion. Check that the inner duct for oil delivery to the pump is clear of obstruction. Use a compress ed air j et to clea n the passage.

Check the o i l p um p gear teeth for damage or excessive

wear and f it new gears if necessary. The recommended

backlash is .0059 inch with a maximum wear limit

giving a backlash of .0079 inch. Check the clearance

between the gear teeth and the housing walls in the timing g ear cover. T he recommended clearance is .0 01 2 to .0035 inch with a maximum of .0047 inch. Ensure that the drive gear is firmly attached to its shaft. Upon assembly there is a pinch fit of .0016 to .0031 inch

betwee n the tw o parts.

The driven gear to shaft clearance upon assembly is

.00079 to .00236 inch with a maximum wear limit of

scoop and remove any obstruction. If the screen is damaged it must be renewed. Check that the pump drive dog is a good fit on the cam-

shaft and that the dogs are not badly worn so as to

impair the pum p operation. Reassembly of the pump is the reverse procedure to

dismantling. Ensure that the pump cover piate is correctly located by means of the dowel on the timing gear co ver.

Station wagon:

A helical-spur gear type oil pump is driven from the

lower end of the distributor drive spindle which is in mesh

with the camshaft. The gears are located in a special

housing in the bottom of the timing gear housing and are held in place by a cover plate. The oil pressure relief valve is located at the driven end of the camshaft.

A pump suction oil filter is fitted in the sump and this connects to a duct in the timing gear case s o supplying oil to the pump (see FIG 1 : 37) .

.0039 inch. Also check the width of the drive and driven

gears which when new should be .3937 to .3928 inch with a minimum width of .3917. In service a spare drive gear is supplied complete wi th its shaft.

Pump gears removal, inspection and reassembly:

To remove th e pump gears from the timing gear cover

proceed as follows:

Drain the oil sump to ensure that the oil does not syphon

out. Thoroughly clean the area around the pump body

(see FIG 1 :37 ).

Remove th e e nd cove r plate by releasing the retaining

bolts and washers. Carefully ease the driven gear downwards fo ll owed by the driving gear and shaft Clean all parts removed and blow clean using a com-

pressed air jet. Inspect the timing gear cover pump area

for cracks o r distortion. Check t hat th e inner duc t for oi l

delivery to the pump is clear of o b s t r u c t ion. If in doubt remove the drain plug and filler cap and use a compressed air jet to clean th e passage. Check the gear teeth for damage or excessive wear,

ensure that the drive gear is firmly attached to its spindle and that the end cover plate is not badly scored or pitted. Fit new parts as necessary. Reassembly is the reverse procedure to dismantling,

taking care that all parts are assembled clean and the end cover plate seating correctly wi th a new gasket.

1:14 Lubrication, oil filter, relief valve Description :

The engine is pressure lubricated through a gear type pump which is incorporated in the timing gear cover and driven from the camshaft by dogs or gears. The lubrication circuits are shown in FIGS 1 :36 and 1 : 37.

The pump draws oil from the sump through a suction

horn fitted wit h a filter screen which is fixed to the crank-

case b y a d uc t in t he timing gear cover. This

supplies oil

to the pump.

Oi l passes fro m t he camshaft rear sea t o n t o t h e cr a nk -

shaft rear support where it flows into an adjacent chamber.

From here the oil flows through ducts in the crankshaft

from end to the centrifugal oil filter. The centrifugal filter,

which also acts as a pulley for the generator and blower drive, rotates wit h the crankshaft.

Oil from the filter enters a passage in the crankshaft, where it lubricates the main and connecting rod bearings and passes from a special groove in the front main bearing and ducting in the crankcase into which is inserted the oil pressure warning sender unit, and also the delivery pipe for oil to the overhead valve gear.

The pu shro d sleeves provide the return path for the oil from the cylinder head and delivers oil to the tappet gear

and the camshaft cams. The tappets are suitably drilled

to allow correct circulation of the oil. The tappets are

located in two casting cavities, one of which communicates with the timing gear housing and the other one to the crankshaft front drain support drain.

The oil pressure is regulated by a pressure relief valve 5

(see FIG 1 :38) mounted at the rear end of the camshaft.

It comprises a hubbed disc which slides o n a guide 6 of the oil pump drive shaft 7. Under spring load 9 the valve disc circumferentially closes an annular chamber which communicates wi th t he lubrication circuit. Excessive o il pressure causes the disc to uncover the chamber.

FIG 1:38 Engine longitudinal section thro ugh oil pump

Key to Fig 1 :38 Suction scoop 2 Hole in crankcase

3 Duct in timing sprocket cover 4 Timing sprocket cover 5 Oil pressure relief valve 6 Drive shaft guide and oil pump cover 7 Oil pump driving gear shaft 8 Camshaft 9 Oil pressure relief valve spring

Centrifugal oil filter:

The oil filter is of the centrifugal type comprising of

tw o flanges and an oil slinger. The filter is attached to the

rear end of th e cr ank sha ft as s hown in FIG 1 :38. The outside diameter of the oil slinger (see FIG 1 :39) is

smaller in diameter than that of the flanges but of such a

F500

FIG 1:39 Centrifugal oil filter components

Key to Fig 1:39 1 Drive pulley 2 Rotor hub

3 Seal ring 4 Oil slinger 5 Lockplate 6 Hub-to-crankshaft hollow screw 7, 8, 9 Pulley-to-hub mounting screws, toothed washers and plain washers

FIG 1 :40 Engine detail showing lube oil passages

Key to Fig 1 :40 1 Splines in crankshaft for oil passage

to filter 2 Oil inlet into circuit from filter 3 Hole for oil passage to main bearing

A groove is machined on the outer flange periphery to

form a pulley for the generator and blower drive belt.

Cleaning and inspection:

To ensure a reliable lubrication system there must be no oil leaks from the gasket betw een th e outer and inner flanges. Every time the engine is overhauled the filter must be dismantled, cleaned and new gaskets fitted. To clean the filter, remove the six screws and washers and separate the drive pulley and hub. Carefully scrape the inner surfaces to remove all sludge.

Upon reassembly the filter to crankshaft hollow mounting screws must be tightened to a torque wrench setting of 1 08.5 Ib ft. The cover to mounting flange screws must be tightened to a torque wrench setting of 5.8 Ibft.

Oil pressure indicator sender unit:

The o il pressure indicator sender uni t is located on the righthand side of the cylinder block and is connected to an indicator light in the instrument cluster on the dashboard.

The red indicator lights only when the ignition is switched on and goes out when oil pressure has built up to between 8.5 and 14 Ib/sq in.

Should an accidental shortcircuit occur in the oil pressure indicator circuit, the sender un it may be damaged

so the cause must be traced and rectified before the unit

is renewed.

FIG 1 :41 Timing marks on sprockets. On later cars th e

crankshaft key way is on the underside

size t hat centrifugal force does not sling oil into the area where the foreign matter is collected. The outer flange

inner face has radial vanes on its face which retain the foreign matter and the oil is conveyed to the centre of the filter.

The oil to be filtered issues from the side splines 1

(see FIG 1 :40) of the crankshaft and is forced by the

slinger to the periphery of the filter where it is cleaned and

returns to the centre of the filter and into the crankshaft

drilling 2. The inner flange or hub and the slinger are secured to the crankshaft by a special hollow screw 6 as

shown in FIG 1 :39, the outer flange is attached to the

hub by six screws.

1:15 Valve timing

If the camshaft has been disconnected from the crank-

shaft for any service operation the valve gear will have t o

be retimed and to do this proceed as follows: 1 Turn the crankshaft until the reference line on its

sprocket is pointing towards the camshaft as s hown in

FIG 1 :41.

2 Turn the camshaft until the reference dot on its

sprocket registers wi th the crankshaft sprocket. Leave the shafts undisturbed and carefully mount th e chain. Should it be necessary to check the valve timing and

sprocket marks, proceed as follows:

1 Fit Fiat C.673 tool as shown in FIG 1 :42.

2 Temporarily adjust the valve stem-to-rocker arm

clearance of cylinder No. 1 at .01 77 inch for the inlet valve and .01 50 inch for the exhaust valve (Model 500 engine) or at .01 54 inch for both valves (Model 500 sports).

3 Rotate the crankshaft and set the flyw he el timing mark

at ' O' on th e gradu ated sector. Check th at the sprocket marks are correctly lined up in this position.

If the engine is being assembled, to install the driven

gear, proceed as follows:

1 Set the timing mark o n the drive sprocket towards the

centre of the camshaft.

2 Position the driven sprocket on the camshaft mounting

flange with four screw holes in line and tighten two mounting screws only.

3 Rotate the camshaft until the driven sprocket mark

registers wi th the reference line on the drive sprocket.

4 Remove the driven sprocket without moving the

camshaft. Install the timing chain and replace the driven sprocket. Tighten the four screws to a torque wrench setting of 6.5 Ib ft.

5 Using the graduated sector check that all the valve

timing angles are as detailed in Technical Data.

Readjust th e valve stem to rocker arm clearance to th e

correct setting.

1:16 Valve stem-to-rocker clearance adjustment

It is important that the clearance between the valve stem and rocker is kept to the recommended figure of .0059 inch, measured when the engine is cold.

If the clearance is excessive o pera ting noise will occur

and if less than recommended the valves will stay open

too long which will result in damage to the valve face

and its seating.

Inspect the contacting surfaces for scoring or pitting:

if it is excessive, new parts must be fitted. Also check

the condition of the rocker-to-valve and rocker ball

head-to-pushrod contact surfaces are free from wear or pitting. The faces must have a mirror finish.

The oilway in the rockers and shaft must be thoroughly inspected and free from sludge, otherwise lubrication failure will occur.

The assembly clearance between the rocker arm and shaft should be .00063 to .00217 inch and the clearance between the rocker shaft and the shaft support should

be .00020 to .00138 inch with a maximum wear limit of

0039 inch.

Turn the engine until the valves of one cylinder are in balance, that is, the inlet valve opening and the exhaust valve closing. The other cylinder will now have bo t h valves fully closed. Adjust the valves on this second cylinder by

loosening the locknut, and turning the

adjuster as shown in

FIG 1 : 43 to obtain the desired clearance measured wi th

a feeler gauge. Adjust the clearances on t he other cylinder

in the same manner.

TIMING MARK

FIG 1 :42 Graduated sector C.673 for valve gear timing

1 :17 Engine assembly (sedan — all versions)

To reassemble t he engine proceed as follows:

1 Thoroughly clean and dry all the parts, ensure th at a ll

drillings are free from dirt or sludge and place on a clean dry surface.

2 Carefully install the cylinder-piston-connecting rod

assemblies with new paper gaskets between the cylinders and crankcase seats.

3 Refit the big-end bearing shells to the connecting

rods, ensuring that they are free from any dirt or metallic particles. Carefully ease the crankshaft into the crankcase, lubricat e the main journals wit h clean engine oil, place a new paper gasket between the supporting member and the flywheel end of the crankcase. Install the supporting member and b ear ing assemblies. Secure the supporting members with the screws and special toothed washers.

4 Locate the connecting rod big-end half onto the

crankpin journals, liberally lubricate the journals with

fresh engine oil, fit the remaining shell half, matching

bearing end cap and tighten the bearing cap nuts to a torque wrench setting of 23.9 Ib ft.

5 Inspect the camshaft bearing bores and remove any

burrs w it h a hand scraper wetted with oil. Carefully slide in the camshaft ensuring the cam lobes or gear teeth do not score the front bearing bore.

6 Fit a new timing gear cover paper gasket held in

place w i t h a little grease. Install the outer thrust ring,

FIG 1 :43 Adjusting the rocker clearances using the

optional service tools. Refer to Technical Data for the

correct clearance on early and late engines

inner thrust ring, shoulder washer and slide on the camshaft drive sprocket, locking it with the Woodruff

key. Assemble th e timing chain and driven sprocket,

ensuring that the timing marks on the sprocket are

indexing as shown in FIG 1 :41. Secure the driven sprocket with six screws and lockplates and carefully bend down the lockplates.

7 Install the timing gear cover, the oil pump, oi l pressure

relief valve and seal assembly. Secure with nuts, special toothed washers and plain washers located

in the same manner as was noted on dismantling.

Locate the oi l p um p su ction horn and secure with the

nuts and toothed washers.

8 Install the flywheel in the same relative position to the

crankshaft as was noted on dismantling. Replace the

F500

FIG 1 :44 Cylinder head hold-down nuts tightening

sequence. 500 Sedan

ROTATION DIRECTION

C/ROD NUMBER

FLYWHEEL END

TIMING CHAIN END

FIG 1 :45 The correct position of connecting rodpiston assembly on engine 120.000

EXPANSION SLOT

CAMSHAFT

CYLINDER No. 2

CYLINDER No. 1

screws and together with new lockplates tighten to a torque wrench setting of 23.1 Ib ft. Bend down the lockplates.

9 Slide the centrifugal oil filter mounting flange, the

oil slinger and the mounting screw together with its lockplates onto the crankshaft and tighten the screw to a torque wrench setting of 108.5 Ib ft. Bend down the lockplate.

10 Assemble the clutch assembly to the flywheel and

using Fiat pilot A.62023 centralize the driven plate

to the pressure plate assembly. Secure the pressure

plate assembly using screws and toothed washers.

11 Fit ne w oil pan cork gasket, if necessary using a little

grease to hold in position and carefully fit the oil pan securing with screws, toothed washers and lockplates. Bend down the lockplates onto the screw

heads.

12 Fit the oil cooling air conveyor on the oil pan and

secure with screws and toothed washers.

13 Carefully turn the engine over and fit the centrifugal

filter mounting flange rubber seal. Fit the oil filter

cover and secure with screws together with plain and toothed washers to a torque wrench setting of

ft.

5.8

14 Ensure the faces of the cylinder head and cylinders

are free from dirt and oil and carefully slide the cylinder head gasket over the studs ensuring that it

is the correct way up. Insert the tappets in the same order to removal together with the sleeves, pushrods, oil delivery line to the rocker arm shaft and t he casing with its seal ring.

15 Thoroughly inspect the cylinder head to ensure that

it has been correctly reassembled, carefully slide it

over the studs and secure using the four cap nuts

internally and four standard nuts and plain washers

externally. Tighten the nuts in the order as shown in

FIG 1 :44 or 1 :46 to a torque wrench setting of

23.9 Ib ft.

16 Fit the rocker arm shaft and arm assembly together

with the two supports. Tighten the supports using screws, plain and toothed washers to a torque wrench setting of 15.2Ibft. Adjust the tappet-to-

rocker clearance as detailed in Section 1 :16.

17 Temporarily plug the intake duct hole to ensure that

no foreign matter finds its way into the engine.

Install the spark plugs having ensured that they are clean and correctly adjusted.

18 Reassemble the engine cowling and air

throttle valve assembly which should be secured on the top side using two nuts, two plain washers and two toothed washers, on the underside with two screws and tw o toothed washers, and centrally using

one screw and one spring washer.

19 Fit the toothed washers on the end of the spark plug

electrode and tighten the terminals together with the special rubber boots.

20 Refit the fan, generator and ground cable assembly

and secure the crankcase, also the warmed air intake shrouding. Finally tighten the generator to fan nuts.

21 Fit both lower exhaust silencer mounting brackets

onto the crankcase but do not tighten fully. Fit the

air conveyor and secure to th e engine cowling using six screws, six toothed washers and one nut together with a toothed washer. Join together the two

exhaust

sections of the air conveyor securing with seven screws, seven toothed washers and five nuts.

22 Slide the fuel pump control rod into its seating,

assemble the insulator between oil wetted graphite gaskets and f it the p ump to the crankcase using nuts and toothed washers.

23 Fit the air conveyor cover complete wi t h the accelera-

tor control relay lever and rod. Secure using eight mounting screws, eight toothed washers, eight plain washers and e ight nuts. Fit the fuel line retaining clip which is secured by one of the air conveyor upper screws. Install the generator and fan drive pulley

having first placed four adjusting rings between the pulley halves and the thrust ring on the outside. Secure the pulley to generator shaft using three screws and three toothed washers. Fit the generator fan drive belt.

24 Refit the carburetter having first positioned the

bakelite heat shield between the two oil moistened graphite gaskets. Secure the carburetter using two copper washers and two self-locking nuts. Fit the exhaust silencer and secure to t he exhaust manifolds wi th nuts and spring washers. Place the tw o graphite gaskets between the manifold joints. Fit both exhaust silencer upper mounting brackets and secure them on the to p side to the brackets already in place w it h

nuts and toothed washers on the bottom side with screws and toothed washers.

25 Carefully position the distributor at a 10 deg advance

setting and secure with a

nut, plain washer and spring washer. Fit the fuel pump to carburetter line complete with mounting bracket rubber lining and

secure the line with two clamps. If difficulty is

experienced in positioning the fuel line i nto the pump or carburetter funnels it is suggested that the line ends should be heated in hot water and thoroughly

dried before installing.

26 Install the air cleaner elbow and rubber hose assembly

on the top of the carburetter using a graphite gasket

in between and secure w ith nuts, plain washers and

spring washers. Carefully position the air cleaner, line and hose assembly and connect it to the elbow.

Secure the cleaner to air conveyor cover using screws and toothed washers.

27 Fit the spark plug cables complete with the rubber

grommet for cable mounting bracket on engine cowling and connect the cables to the distributor and spark plugs. Fit the oil pressure gauge sender unit together with its sealing washer.

28 Install the cylinder head cover and oil breather pipe

assembly with a cork gasket inserted between.

Secure with self-locking nuts and fibre washers. Connect the accelerator control relay lever rod to the carburetter and secure with the clip.

29 Fill the oil pan w ith the correct grade and quantity of

oil, insert the dipstick and the engine is ready for refitting.

FIG 1:46 Cylinder head stud nut tightening sequence.

500 D. F and L Sedan and Station Wagon

FIG 1 :47 Power plant rear suspension

Key to Fig 1 :47 1 Suspension arm 2 Screw,

rubber pad to bracket 3 Bracket-to-engine nut 4 Nut, arm to bracket 5 Arm bracket 6 Spring 7 Arm pin-to-support nut 8 Screws, pin to support 9 Pin arm to support

1:18 Engine assembly (station wagon)

Reassembly of this engine is straightforward as it is the reverse procedure to dismantling. It is recommended that Sections 1 :5 and 1 :17 are studied as the assembly technique is similar for both the horizontal and vertical

F500

cylinder engines. The following points should however be noted: 1 Refer to FIG 1 :45 for the correct positioning of the

connecting rod-piston assembly on the 120.000 engine.

2 The sequence of tightening the cylinder head nuts is

different, the new order being given in FIG 1 :46.

FIG 1 :48 Power plant front support cross-section

FIG 1 :49 Checking the generator and blower drive belt tension

Key to Fig 1 :49 A Normal give-in: about 13/32 inch under

a 22 Ib pressure B Nuts securing the pulley halves with spacer rings

When the V-belt has been correctly adjusted the belt should sag 13/32 inch under a hand pressure of about 22 lb as shown in FIG 1 :4 9 .

Should the belt be too slack the generator and centrifugal fan will not operate at the correct speed causing overheating and a discharged battery. Also the

belt will slip causing rapid wear of the belt. Conversely

if the belt is too tight excessive loading will be placed on the generator bearings causing excessive bearing wear and noisy operation.

To adjust the belt tension proceed as follows:

1 Remove the three nuts 'B' (see FIG 1 :49) on the

generator pulley and this will split the pulley into two parts between which are spacer rings.

2 The tension of the belt is increased or decreased by

either reducing or increasing the number of spacers.

3 Place the spacer rings removed from between the

pulley halves o n th e pulley outer face so tha t the ring s may be re-inserted when fitting a new belt.

4 Tighten the three nuts to a torque wrench setting of

14.5

lb ft.

1 :21 Modifications

Since its introduction the Fiat new 500 model has been continually de velop ed. The main modifications that have been made are as follows:

1 Heating system safety device 2 Recirculation device for the blow-by gases 3 Cylinder head modified to incorporate item 1 4 Double valve springs fitted 5 Cylinder barrels m odified to incorporate item 1 6 Flywheel modified to incorporate new type diaphragm

spring clutch mounting

7 Larger air cleaner container.

Details of these modifications are to be found in the relevant sections if they necessitate a change in service overhaul procedure. Other information is to be found in

Technical Data.

1 :19 Power plant mountings

The combined power and transmission unit is elastic-

ally mounted on two supports.

The front of the unit rests on a crossmember which is secured under the car floor through two rubber block mountings that are bolted to the gearbox casing as shown in FIG 1 :48. The position of the rubber blocks on the crossmember is adjustable so that the assembly can be correctly aligned.

W ith th e rear of t h e unit the engine crankcase is sprung to the body rear crossmember through an articulated swinging arm that compresses a coil spring as shown in

FIGS 1 :47 and 1 :49. A rubber bump pad is mounted inside the spring to give a progressive action.

Whenever the power and transmission unit is being serviced the condition of the mountings should be

checked and any worn or damaged parts renewed.

1 :20 Adju stment of generator and fan drive belt

The centrifugal oil filter cover/pulley on the crankshaft transmits the drive through a V-belt to the generator and centrifugal fan pulley.

1 :22 Fault diagnosis (a) Engine will not start

1 Defective coil 2 Faulty distributor capacitor (condenser)

3 Dirty, pitted or incorrectly set contact breaker points

4 Ignition wires loose or insulation faulty 5 Water on sparking plug leads 6 Corrosion of battery terminals or battery discharged 7 Faulty or jammed starter 8 Sparking plug leads wrongly connected 9 Vapour lock in fuel pipes

10 Defective fuel pump 11 Overchoking 12 Underchoking 13 Blocked petrol filter or carburetter jets 14 Leaking valves 15 Sticking valves 16 Valve timing incorrect

17 Ignition timing incorrect

(b) Engine stalls

1 Check 1 , 2, 3, 4, 10, 1 1, 12 , 13 , 1 4 and 15 in (a) 2 Sparking plugs defective or gaps incorrect 3 Retarded ignition

4 Mixture too weak 5 Water in fuel system 6 Petrol tank vent blocked 7 Incorrect valve clearance

1 Check 1 and 6 in ( b) 2 A ir leak at manifold joints 3 Slow-running jet blocked or out of adjustment 4 Air leak in carburetter 5 Over-rich mixture 6 Worn piston rings 7 Worn valve stems or guides 8 Weak exhaust valve springs

(d) Engine misfires

1 Check 1, 2, 3, 4, 5, 8, 10 , 13, 14, 1 5, 16, 17 in (a);

2, 3, 4 and 7 in (b)

2 Weak or broken valve springs

(e) Engine overheats

1 Generator and fan drive belt too loose

2 Shutter or thermostat seized in closed position

(f) Compression low

1 Check 14 and 15 in (a), 6 and 7 in (c) and 2 in (d) 2 Worn piston ring grooves 3 Scored or worn cylinder bores

(g) Engine lacks power

1 Check 3, 10, 1 1 , 13 , 14, 15, 16 and 17 in (a), 2, 3, 4

and 7 in (b) 6 and 7 in (c) and 2 in (d). Also check (e)

and (f ) 2 Leaking joint washers 3 Fouled sparking plugs 4 Automatic centrifugal advance not operating

(h) Burnt valves or seats

1 Check 14 and 15 in (a), 7 in (b) and 2 in (d). Also

check (e)

2 Excessive carbon around valve seat and head

(j) Sticking valves

1 Check 2 in (d) 2 Bent valve stem 3 Scored valve stem or guide 4 Incorrect valve clearance

(k) Excessive cylinder wear

1 Check 11 in (a) and see Chapter 4 2 Lack of oil 3 Dirty oil 4 Piston rings gummed up or broken 5 Badly fitting piston rings 6 Connecting rods bent

(l) Excessive oil consumption

1 Check 6 and 7 in (c ) and check (k) 2 Ring gaps too wide 3 Oil return holes in piston choked with carbon 4 Scored cylinders 5 Oil level too high 6 External oi l leaks 7 Ineffective valve stem oil seals

(m) Crankshaft and connecting rod bearing failure

1 Check 2 in (k) 2 Restricted oilways 3 Worn journals or crank pins 4 Loose bearing caps 5 Extremely low oil pressure 6 Bent connecting rod

(n) High fuel consumption (see Chapter 2 )

(o) Engine vibration

1 Loose generator bolts 2 Blower blade assembly out-of-balance 3 Incorrect clearance for rear engine mounting rubber

F500

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CHAPTER 2

THE FUEL SYSTEM

2:1 Description 2:2 Fuel pump operating principles 2:3 Routine maintenance 2:4 Pump removal, dismantling and examination 2:5 Reassembly, installation and adjustment 2:6 Carburetter operation and adjustment,

Weber 26.1MB

2:1 Description

All the new 500 models use a mechanical diaphragm fuel feed pump as shown in FIG 2:1. Four types of carburetter are fitted depending on the model to which the engine is installed. Each carburetter operation and adjustment is fu ll y described, together with details of the recirculation device for bl ow -b y gases and oi l vapours.

2:2 Fuel pump operating principles

Refer to FIG 2 :2 . An eccentric on the rotating camshaft

actuates the oper atin g rocker 21 via a pushrod 25 which

depresses th e diaphragm 14 and so creates a depression

in the pumping chamber located in upper body 5. Under atmospheric pressure, petrol passes through the pipeline connection and inlet valve into the pumping chamber.

The return spring 15 then raises the diaphragm, expelling

the petrol through the outlet valve and pipeline to the carburetter float chamber.

When the float chamber is full, the pressure in the pipe-

line and pumping chamber holds the diaphragm depressed

against the tension of the return spring.

2:7 Modifications

2:8 Carburetter operation and adjustment,

Weber 26.OC 2 :9 Air cleaner 2:10 Blow-by gases recirculation device 2:11 Fuel tank 2:12 Fault diagnosis

2:3 Routine maintenance

A poor delivery of fuel to the carburetter may be due to a fault in the fuel pump or related lines. Periodically the pump body screws 19 (see FIG 2:2) and upper cover screw 1 should be checked for tightness. The fuel pump lines should be disconnected and checked for freedom of

restriction, chafing and loose con nections. The fuel pump

filter should be removed and cleaned periodically.

2:4 Pump removal, dismantling and examination

The pump is located on the carburetter side of the engine crankcase (sedan) or under the generator at the front of the crankcase (station wagon).

Removal: 1 Disconnect the fuel pipe from the tank to stop petrol

syphoning out of the tank and then release the fuel inlet and outlet pipes fr om th e pu mp body.

2 Remove the tw o nuts and washers holding pump to

crankcase.

3 Carefully lift away the pump, gaskets and insulating pad

fro m the crankcase (see FIG 2: 3).

F500

TO CARBURETOR

FROM TANK

CONTROL ROCKER

FIG 2: 1 Fuel pump. Arrows point to fuel inlet and outlet

Dismantling:

1 Refer to FIG 2:2 and remove the cover mounting

screw 1 and washer 2. Lift off cover 4 and filter 13. Mark the relative position of the two halves of the pump body. Remove the pump bodies interlocking screws 19

and separate the upper half from the lower half of the

body.

2 Push down the centre of the diaphragm assembly 14

and rotate through 90 deg. to release diaphragm from the rocker 2 1 . L ift o ut dia phragm and spring 15.

3 Release the two valve assemblies in t he upper body by

removing the valve retaining plate locking screws 11 , and l ifti ng out the plate 12 , gasket 10, valve springs 6 and 9, and valves 7 and 8.

4 Using a pin punch remove the rocker pivot pin together

wi t h the t w o washers and carefully lift away rocker and

reaction spring.

5 Thoroughly wash all components in petrol and

blow dry with compressed air or a foot pump. Inspect the valves 7 and 8 for evidence of damage and valve springs 6 and 9 for weakness or cracks. Check to see that the

diaphragm reaction spring and rocker are not distorted or unserviceable. Generally inspect all parts for cracks, distortion and the diaphragm for stiffness and also the rocker and pin f or wear.

2:5 Reassembly, installation and adjustment

Ensure that all parts are clean and dry. Assembling is the

reverse procedure of dismantling. Lubricate the rocker lever and pin before placing them in the lower body.

FIG 2:2 Fuel pump components

KeytoFig2:2 1 Cover screw 2 Screw gasket

3 Cover gasket 4 Cover 5 Upper body 6 Spring for inlet valve 7 Inlet valve 8 Outlet valve 9 Spring for outlet valve 10 Plate gasket 11 Plate screws 12 Valve retaining plate 13 Filter gauze 14 Diaphragm, complete with tie rod 15 Return spring 16 Spring thrust cup 17 Felt 18 Washer for felt 1 9 Connection screws 20 Lower body 21 Rocker 22, 24 Gaskets 23 Insulating pad 25 Pump control

pushrod

Installation:

Carefully slide the pump control pushrod into the

crankcase, assemble the two gaskets wi th the i nsulat ing pad in between and slide over the pump retaining studs.

Ease t he pump towards the crankcase ens uring the pushrod locates correctly in the rocker en d. Finally tighten the tw o retaining nuts and spring washers.

2:6 Carburetter operation and adjustment, Weber 26.IMB

Al l 5 00 Sedans are equipped wit h Weber type 26. IMB carburetters with detail differences only between the models. The carburetter is of a downdraft single choke

FUEL

PUMP CONTROL

PUSHROD

INSULATING

FUEL PUMP

FIG 2:3 Fuel pump and control pushrod

PAD

design with a 1.0236 inch diameter throat measured at the height of the throttle shaft. The amount of charge passing to the manifold is controlled by a throttle butterfly valve from an accelerator pedal operating a lever secured to the throttle valve shaft via a cable. The carburetter is fitted with a progressive action starting device which enables t he driver to suit the mixture richness to the most arduous of starting conditions, and will enable the engine to run evenly until it reaches its normal operating temperature.

A dampened needle valve ensures a smooth running engine as it is not affected by engine vibrations and therefore giving a constant fuel level in the carburetter bowl. A secondary venturi is incorporated in the single casting of the carburetter body and this has a diameter of 0.8268 inch.

Carburetter operation:

Filtered air flows through the venturi 24 (see FIG 2 :4) wher e it mixes wi th fuel flowing from the nozzle 2 5 and the charge is then conveyed to the cylinders through the primary venturi 21 and throat, where the throttle butterfly 19 controls the amount of charge.

Petrol flows from the main fuel line to the bowl 16 through a gauze filter 7 and needle valve 10, where the float 12 pivoting at point 11, controls the opening of the

needle 10 so maintaining a constant fuel level. From the bowl 16 fuel reaches the emulsion well 23 via the metered

main jet 15 wh ere, after having been mixed with the air coming from the metered air corrector screw 1, through the emulsion orifices 22 and spray nozzle 25, it finally

reaches the Venturis where it mixes with the air stream

FIG 2:4 Diagrammatic section of Weber 26.IMB

carburetter

KeytoFig2:4 1 Air corrector jet 2 Air inlet

3 Idle speed mixture duct 4 Idle speed j et holder 5 Idle speed air orifice 6 Filter cover 7 Filter 8 Fuel inlet connection 9 Needle valve seat 10 Needle 11 Float pivot 12 Float 13 Idle speed jet

14 Main jet holder 15 Main j et 16 Bowl 17 Idle speed mixture adjustment screw 18 Idle speed mixture orifice 19 Throttle 20 Transition hole 21 Primary venturi (not interchangeable) 22 Emulsion orifices 23 Emulsion well 24 Secondary venturi

(not interchangeable) 25 Main nozzle

FIG 2:5 Starting device (choke) diagrammatic section

KeytoFig2:5 A Device fully inserted B Device partially inserted C Device disinserted 2 Air inlet 16 Bowl

19 Throttle 21 Primary venturi 24 Secondary venturi 26 Mixture duct 27 Mixture leaning air orifice 28 Transition duct 29 Transition mixture orifice 30 Starting mixture orifice 31 Transition orifice 32 Starting mixture orifice 33 Starting valve 34 Mixture duct 35 Starting device air orifices 36 Rocker 37 Lever return spring 38 Starting device control lever 39 Control wire screw 40 Cover with support for starting device control bowden 41 Starting valve spring 42 Spring casing. 43 Starting jet emulsion air orifice

44 Air emulsion reserve well orifice 45 Starting reserve well 46 Starting jet

F500

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