Franklin 6A4-150-B3, 6A4-165-B3, B31 Service Manual

SERVICE MANUAL

FRANKLIN AIRCRAFT

ENGINE

M

ODELS

6A4-150-85, 851, & 6A4-165-B5

4IRCOOLID

MOTOIS,

II~.

SYRACUSB.

HEW

YORI:

V.I.

A.

C

A.La

ADDRES.

AIRCOOLED

FRANKLIN

AIRCRAFT

ENGINES

Model

6A4-150-B5,·

B51,

&

6A4-165-B5

"NOT

LIABLE

FOR

ACCURACY

AND

EFFECTIVENESS

OF

ORIGINAL

TEXT."

Air Service Caravan

Co.,

Inc.

INSPECTION,

MAINTENANCE

AND

OVERHAUL

INSTRUCTIONS

C

LLEGt

F I

'0

J

ST.

I L

TECH

OLOG

AIRCOO

LED MOTOR

S, I

NC.

SYRACUSE

8,

NEW

YO

RK

TABLE

OF

CONTENTS

Se

cti

on

Page

S

ection

P

age

In

troduction

______

___

_______________

____ ____ ______

__ 5

XVII

Valves

and

Va lve Springs.......

___

.....

_____

25

Valves

__

... _

.......

__.

....

_......

_______

._._

... _..

25

II

Wa

rra n

ty

____

____________

_____

__.

________

____

._____

__ 5

Valve

Springs_

.... _.

____

._.

__

.. _

___

...

_____

... _

25

XVIII

Valve

Actuati

ng Mec

hanism.

____ .__

..__

__

26

III

Omit

7

Hydraulic Lifters

____ .__

..

__

..... _.. __..... ____

26

Hydraulic Lift

er

(Servicin

g)

..........._ 27

IV Repl

acement

Parts

and

Shipping

Lifter

Rods

and Tube

s_......

_. ____

..

_______

28

In

structions _______

_______

__

______

____ ____ ___ ___ 8

Rocker

Pins

a nd

Rockers

______

... _...

_.

__ . 28

V Eng i

ne

Specifications____

____

__ __ __

____

___

_____

9

XIX

Lubricating

System___

.. _...

__

._

.... _.. _.. _.

.....

29

Lubricating

Syste

m- I

nspection

and

Se

rvicing._.

___ .___

......

_._

.. _..

___ .__

29

VI

Table

of

Limits

and

Tolerances___ _____

__

10

Oil

Pan

_._..

___

____

..

___ .______

...

_.

__

._

......

____ . 30

Oil

Pump___. _

__

...

__

..

___

..... _

_____________

..

_.

__

30

VII

Re

comme

nded T

ightening

Torque

Oil

Inlet

Flo

at

(Flot o) _..

___

._.

__ .__ ._.

___

30

Valu

es _____

____

____

_________________ _____

_________

12

Oil By-

Pass

Plate

______________

__.

______ .._.

___

3 1

VIII

~Overhaul

Perio

ds

and

XX

Inlet

Manifold ______

.. . __. __

__

.. _____

___

.. _....

___

32

I

Perio

dic I ns

pec

tions

Check

List

______12-13

XXI

Accessory

Gear

Train

___

__ .__________

._.

____

.. _

33

IX

En

gin

e L

ubrication-GeneraL

__________

__

14

Magneto

Drive

Geor and Hub._.

_____

._

33

Magneto

Driven

Gear

___ .__ .._._

... _...

____

33

Generator

Driven Gear

___

.__.

__

.. _..

_.

____

33

X

Crankca se

______ ______

___

._

____ ___ _______

____

______ _ 14

Tachometer

Drive. __..

__

...

__ .___

..

____._.

___

33

Starter

Gear

Assemb

ly ... _...

____

..

___

..

___ . 34

X I

Cra nkshaft _____

______

____ ________________

_

_____ ___

15

C

rankshaft Bear

ings_____

______

_________

____

16

XXII

Ignition _____

___

__ .__

_______

... _____.__

___

...

_._ ..__

._

35

Cranks

ha

ft

Oil

Seal.-__

___

_________________

16

Magnetos-Pri

nci

ples

of Operation

35

1m

ulse

Starter

on the LA- 6

and

XII Ca

msha

ft

___

___________________._._

._________________

17

S6RN-21

Ma

gneto

s _

________._.

_._.

____

36

Magneto

Installati

on

.__

._

..

___

__

._________

39

Eisemann

Magnetos

-M

inor

X I

II

Timi

ng

Gear Case _

_______ .._______________

_______

17

Inspection .__

....

__

._

..

_.

___

__ .________

...

_.

37

Magn

eto T i

ming Check____ .___

.. _.

..

__..

___

38

XIV Connecting Rods_______________________

_..

______

__

18

Bend

ix-Sci nt i 110 Magneto_______

.. _

___

._.

38

Spa

rk

Plugs

__ ..______ .____

._

.. _...

__

.___

._.

______

38

XV Piston, Pis

ton Pins and Rings

___

____.______ 19

Pis

ton _______.____________

___

________

_________

___

___

19

XXIII

Carbureti

on .. _____..

_____________ ._____

.__

_________

40

Pis

ton

Pin _

__

______________________

_______________

19

Pist

on Rings

__ __ _____ .__

______

__.

_____

___

_____

__

20

XXIV

Generator

and

Volta

ge

Regulator._ ..____

42

Gen

erator

...._____

._

. __

_____ .___

...

_____ ._______

_ 4 2

Volt

age

Reg

ula

tor_____

..

_. ___

_______________ . 42

XVI Cy

linder

Assemb

ly ___

______

_________

.. __

__

______

2 1

Cylinders

__.

__ .________________._. ___.

__

...

__

....

21

XX

V

Starting Mo

tor

_._

.. _..

_.

____._. _______

...

____

.....

43

Va

lve

Guides

________

__.

______

__ .__

..... ___ .____

. 21

Valve

Seat Inserts_

___

____

________________ .._.

22

Studs

and

Fastenings.. ______.___

____ .._.

__

22

XXVI

Engine Assembly.

____ .___._____ .___ .____

......

__

44

Fins

__

.. .. _..

___

_.___

__

... _

._

...______.. . _

._. ___

... _

23

He

l icoi

Is

._

.. __._....

__

... . ____._.... .. _.

______..

__

23

XXVII

Engine Run

-In S

chedule

and

Testing

__

48

T

- I TRODUCTION

7 0

Years

of

Frankl in

engineering

experience

plus

the

highest

quality

in

ma terials a nd workm

ans

hip, t

o-

gether

with

the

most modern

manufacturing

methods

are

back

of eve

ry Fran

klin engine shipped from

our

factory.

It

is

the

purpose

of

this

manual

to furnish ready

reference

and

practical information on the operation,

inspection, preventive

maintenance

and

complete overhaul

of

the

model 6A4-1 50-83 a nd 831 and

6A4-165-B3

Franklin engines

and

their

accessories .

The

name

and

data

plate, which is located

either

on

the

starter

Bendix housing

or

on

the

lower right

hand

side of

the crankca

se just above

the

oil pan,

indicates

the

engine

model.

An

effort

has

been

mode

to

arrange

the

material

in

the

manual

so

that

the

description, function, in-

spection

and

repair

of

the

component

parts

of

the

engine

and

its accessories

are

completely covered

in

their

individual sections.

In referring to locations on

the

engine, it is

assumed

that

the

observ er's position

is

at

the accessory

end

of

the

engine, facing forward

in

line with

the

crankshaft.

Hence, t

he pro

peller end

will

be r

eferred

to

as

the

front

of

the

engine

irrespective

of

the

p03ition

the

engine

occupies

in the

air

craft. Cylinders

number

1, 3,

and 5 are

on

the

left side

of

the

engine

and

cyl

inders

numb

er

2, 4,

and 6 are

on

the

right

with

numbers 1 and 2 at

the

rear.

It

is

recommended

in

the

interest

of

safety,

operating economy

and

maximum

service life

of

the

engine

that

the

operating

limits, inspections, tolerances,

maintenance

and

overhaul

instruct

ions

and

methods

be strictly

adhered

to. It

is

also recommended

that

existing instructio ns

of

the

various

air

craft, pro-

peller

and

accessory

manufacturers

regarding

the

servicing

of

their

products

be

rigidly followed.

Additional or revised information will

be

issued

as

it

becomes available. Please keep us advised

of

your

current

mailing

address

to

insure

prompt

receipt

of

this

mat

erial.

To insure

that

your best

interests

be

served

and

satisfaction

be guaranteed,

we re

com

mend that

replacements

be

made

with

genuine

Franklin

parts

only. A list

of

authorized

Franklin d

istribut

ors,

together

with shipping instructions,

appears

on

page

7.

Please

address

all

technical

service inquiries

or

comments

to

Service Division, Aircooled Motors, Inc.,

Syracuse

8,

New York. They

wi

II

receive

prompt

and

courteous

atten

tion.

11-

WARRANTY

Aircooled Motors, Inc.,

warrants

each

new Franklin

engine

or

new

part

manufactured by

it

again

st

defects

in

material

or

workmanship

under

normal use,

but

its

obligation

under this war ranty

is

specif

i-

cally Iimited

to

replacing

or

repai ring

at

its factory

any

such

engine

or part which shall, within

90

days

after

delivery

thereof

to

the

original

purchaser

and

prior

to

50

hours of

operati

on, be

returned

to

Aircooled Motors, Inc., with its permission,

transportation

charges

prepaid, and which upon exa mi-

nation

by Aircooled Motors, Inc.,

is

determined

by Aircooled Motors, Inc. to be defective.

This

warranty

shall

not

apply

to

any

such

engine

or

parts

which have

bee

n repaired or

alt

ered outside

Aircooled Motors, Inc. factory

in

any

way so

as

to

affect,

in its

judgment

, its operation,

or

which h

ave

been

subjected

to

misuse, neglect, improper

maintenance

or

accident,

or

which sha

ll have been

oper-

ated

at

a speed

exceeding

the

factory

rated

speed.

Aircooled Motors, Inc.

makes

no

warranty

with

respect

to

ignition

apparat

us, carb

uretor

s, instrument

s,

tr

ade

accessories,

or

other

equipment

which it does

not

itself build

or manufact

ure inasmuch as such

eq

uipment

is

usually

guaranteed

by

the

respective

manufacturers

thereo

f.

The

foregOing

is

the

exclusive

warranty

made

by Aircooled Motors, Inco Ther

e a re no

other warranties

expressed or implied,

in

fact

or

in

law,

made

by Aircooled Motors, Inc.

AIRCOO

LED

MOTORS, INC.

Syracuse 8, New Yor k

5

....

c

e

....

...

.c

en

Ai

II -

PARTS

A D

SERVIC

E

IMPOR

T

A~T

Save

time

and shipping

expen

se

by ordering all parts from

the

Distributor in your territory. Send your order directly to him. Be sure

to

specify

model and serial number

of

engine for which parts are ordered.

AUTHORIZE

D

FRANK

LIN

DISTRIBUTORS

ALABAMA

Southern

Airways

527

Come

r Bldg., Birmin gha m

3,

Ala.

ALASKA

Pacific

Airmotive

Corporation

Sherril l Field,

Anchorage,

Alaska

ARKANSAS

Arkansas

Aviati on Service

Grider

Field,

Pine

Bluff,

Arkans

as

Central

Flyi

ng

Service

Municipal

Airp

ort,

Little

Rock,

Ark.

CALIFORNIA

Faulkner

Avia tion

Industries

Long

Beach

Municipal

Airport

L

ong

Beach

8,

Californ

ia

Hagel

in

Aircraft

Motors

Co.

933

Airway,

Glend

a le,

California

Rankin

Aviation Industries

Tulare, Califo

rnia

CANADA

Le

avens

Bros.

Air

Services,

Ltd

.

Barker

Airport

, To

ront

o,

Canada

Macleod

Airc

raft

Limited

55

15

Cypr

ess St.,

Vancouver,

B.

C.

Northwest

Industri

es,

Ltd.

Mupicipal Airport,

P. O. Box

517

, Edmonton,

Alb

erta

COLORADO

Moun

tain

States

Aviation

, Inc.

38

00

Dah

lia

Street,

Denver

16,

Colo.

CONNECTICU

T

Simsb ury Flying Service, Inc.

Simsbury

Airport, Si

msbury,

Conn.

DELAWARE

Aircrafters.

Inc.

Airport

, Rehobo

th

Beach,

Delaware

FLORIDA

Wallace Ai r

craft

Company

Sarasota,

Florida

Palm

Bea

ch

Aero

Corp.

L

antana, Florida

GEO RGIA

Aviation

Supply

Corporation

Atlanta

Municipal

Airport

Atla

nta

, Georgio

ILLINO

IS

Snyder

Ai

rcraft

Cor

porat

ion

53 15 W e

st

63 rd St., Ch

icago

38, III.

INDIA A

Air Sa les & Service, Inc.

Wier

Cook MuniCipal

Airport

In

dianapo

lis, In

diana

Munci

e A

viati

on

Corporation

MUncie

Airport, Munc

ie,

Indiana

Roscoe

Turn

er

Aero.

Corporation

Municipal

Airp

ort,

India

napolis, Ind.

Sky

Service

Corp

orati

on

Mun

icip

al

Airport,

Evansville, Ind.

IOWA

Hunter

Flying Service

P. O. Box 18 3, Ce

da

r R

apids.

Iowa

KANSAS

Harte

Flying Service

Municipal

Airport, Wichi

ta, K

ansas

KENTUCK

Y

Kentu

cky

Air

Transpor

t, Inc.

Bo

wman

Field, Louisville 5,

Kentucky

Louisville Fl

yin g Service

Bowman Field, Louisville 5,

Kentucky

MAINE

Airways, Inc.

Munici

pa l A irp

ort, Waterville,

Moine

Sky

Harbor

Flying Se rvice

A

ubu

rn-Lewist

on

Airport

Auburn, Maine

MARYLAND

Capitol

Airc

raft

Sa les

Hy

de

Field, Clinton,

Mar

yland

MASSACHUSETTS

Eastern

Aviation

, Inc.

Wenham,

Massachusetts

JenninQs

Bro .

Air Service

Grafton

Airport,

North

Graft

on,

Mass.

7

MICHIG

AN

Aircraft

Sales

Corporation

1040

Buhl Bldg.,

Detroit

26,

Mich.

Baker-Eberle

Aviation

Corp.

Detroit

City

Airport,

Detroit

5, Mich.

Barr

Aviation

Corp

.

Detroit

City

Airport,

Detroit,

Mich.

Michiqan

Central

Airlines, Inc.

Bishop Flying Service Division

Flint,

Michigan

Northern

Air

Service

Grand

Rapids

Airport

Grand

Rapids

8,

Michigan

MIN

NESO

TA

American

Aviation

Corporation

Flying Cloud Field, Hopkins,

Minn.

Hinc k Flying Service, Inc .

Metropolitan

Airport

Minneapolis,

Minnesota

Van

Dusen

Aircraft

Supplies

2004 Lyndale

Avenue,

South

Minneapolis

5,

Minnesota

MI

SSO

URI

Brayton

Flying Service, Inc.

Lambert-St.

Louis

Airport

St. Louis

21,

Missouri

Hampton

Aircraft,

Inc.

5852

Hampton

Avenue

St. Louis

9,

Missouri

Ong

Aircraft

Corporation

P. O. Box

214,

Kansas

City,

Mo.

Springfield

Flying Service, Inc.

Municipal

Airport,

Springfield, Mo.

Supply Division, Inc.

Lambert

Airport, Robertson, Mo.

N

EBRA

SKA

Omaha

Aircraft

Company

Municipal

Airport,

Omaha,

Neb.

N

EW

HAMPSHIRE

Wm.

E.

Martin

Flying Service

P. O. Box

276/

Concord, N. H.

NEW

JER

SEY

Safair

Flyi~g

School

Bendix

Airport,

Teterboro,

N. J.

NEW YORK

Buffalo A

eronautical

Corp.

Hangar

One, Buffa

lo

Airport

Buffalo, New York

Haven

Flying Service

Sche

nectady

County

Airpo

rt

Schenectady

, New York

Ithaca Flying Service, Inc.

Mun

icipa l Air

port,

Ithaca,

N.

Y.

Leech Airc r

aft,

Inc.

42

0 Lexington A

venue

Ne

w Yo rk 1

7, New York

O'Conn

or

Air

cra

ft Comp

any

Albany

Air

port, Albany, New Y

ork

NORTH CAROLINA

Piedm

ont

Aviation, Inc.

Sm

ith

-Reynolds Air

port

W

inston-Salem I,

Nor

th

Ca rolina

OHIO

Harrington

Air Service, Inc.

Mupici

pa l Airpo rt,

Mansfield,

Ohio

M

etc

alf Flyi

ng Service, Inc.

Toledo Munic ipal Airpor t, Toledo, O.

No rthw

ay

Flying Service

Norton Fie

ld, Colum bus, Ohio

Tri-St

at

e Avi

atio

n Corp.

Cincin

nati

Airport, Sharonv ille, O.

Tusca rawas Co

unty

Aviation, Inc.

Mu

nicipal Airport

New Phila

delph

ia, Ohio

OKLAHOMA

Fr

ank

Clarks

12

25

North

Robinson

Ok lahoma

City 3,

Oklaho

ma

OR

EGON

Westem Skyways Service

18

04

N. E. Union Avenue

Portl

and

12,

Oregon

A.

W. Whitaker

5001 -50

1 5 N.

E.

Uni

on Avenue

Port

land, Oreg

on

PENNSYLVANIA

Boulevard Airp

ort

, Inc.

G

etty

sburg, P

ennsy

lvania

G.

D.

Kelsey

Philadelph

ia

Municipal

Air

port

Philadelphia

42, Pennsy lvania

Krant z

Aeronau

tical C

orp

.

Part

Erie Airport, Erie, P

enn

.

Philadelp

hia

Aviation Corp.

1607

Finance

Building

Philadelph

ia

2,

Penn

sylvania

Scholter Aviati on

Compa

ny

Pitt

sburgh-Butler Airpor t, Butler, Po.

SOUTH

CAROLINA

Carolina

Aviat

ion, Inc.

Municipal

Airport

, Greenville,

S.

C.

Dixie

Aviation Comp

any

Municipa

l Airport, Col

umbia,

S.

C.

Hawth

orne Aero Supply

Hawthorne

Field,

Orange

burg, S. C.

SOUTH

DAKOTA

Dakota

Aviation Co.

W . W . Howes Muni cip

al

Airp

ort

Huron,

South

Dako

ta

TENNESSEE

Capitol Airways, Inc.

Howse Field, Nashvil le,

Te

nnessee

Southern

Air Services

Municipal

Airport, Memphis,

Tenn.

TEXAS

A

ircraft

Sales

Company

Meacham

Field, Fort

Worth,

Texas

Ca

nyon Aviation Service
Canyon,

Texas

Southwest Aircraft, Inc.

Mea

cham

Field, Fo

rt Wort

h, Te

xas

Weatherly-Campbell

Aircraft

Highland

Park

Airport, Dallas, Tex.

VIR

GI

NIA

Coastalair

Corporation

Virginia Beach Airport

Virginia Beach, Virginia

Virginia Airmotive

Woodr

um Field, Roanoke,

Va.

Virginia

Cub

Distributors

Shadwell, Virginia

WA

SH INGT

ON

Northwest

Aircraft

Distributing Co.

Box

649,

Vancouver,

Washington

Northwest

Air Service, Inc.

Boeing Field,

Seattle

8, W

ash.

WEST

VIRGINIA

Glenn T.

Clark

Clark Field, Winfield,

West

Virginia

WIS

CONSIN

Fliteways, Inc.

P.

O.

Box

1808, MilWaukee

1,

Wis.

Racine Flying Se"rvice

Horlick Racine Airport, Racine,

W

is.

IV

-

EPLACEMENT

PARTS

AND

SHIPPING

INSTRUCTIONS

When

con

tactin

g your a u

thorized

Franklin

distributor or

the facto

ry

concerning

par

ts or service,

ple

ase

give

both the

engine

model

and

the

engine serial

numbers

as stamped

on

the

data

plate

on

the

engine. This infor

mation

will

insure prompt,

accurate

service

and

pre

vent

undue

delay. Due to periodic

c

hanges in

engin

es,

the

engine

number

is

most important.

Wh

en

returning

par

ts

to your Franklin

distributor

or

the

factory, att

ach a tag

to

each

part

with your

n

ame, addr

ess a nd

the

model

and

serial

number

of

the engi

ne

from which

the

part

was rem oved,

togeth

er

with

the date

of your original

letter

of

refer

ence

to the p

art

in

que

stion. This

will

assure

the

prom

pt

handling

of your service requests.

When

shipping

parts

to the factory, be sure

they

are

shipped

pre

pa

id

and

that

they

are

carefully

packed

to prevent

damage.

Information regarding parts avail

able

in oversizes

or

und ersizes may be found

in

the

Parts

Book on

the 6A4-

1S0-B3

and

831

and

6A4-165-B3

engines.

Shou

ld

any

problem

arise

which

presents

the

need for specia l handling, or which requi res special

inform

atio

n, we

suggest

that

you

contact

the

neatest

Franklin

Authorized

Distributor or the

factor

y

and every

eff

ort

will

be

made

to

assist

you.

SPECIFY

MODEL

AND

SERIAL

NUM

BE R O F

ENG

I N E

8

fiG.

2.

Three

Quarter

Right Rear View

v- ENGINE SPECIFICATIONS

Model

Number

of

Cylinders

Bore

Stroke

Piston

Displacement

Compression Ratio

Rated

Speed in RPM

Rated

Brake

Horsepower

Idle Speed in RPM

Crankshaft

Rotation

Propeller

Shaft

Rotation

Propeller to

Crankshaft

Ratio

Maximum

Cylinder

Temperature

Maximum

Oil

Temperature
Oil Pressure
Oil Pressure

at

Idle

Oil

Capacity

Oil Specifications
Heavy Duty
Heavy Duty

Maximum

Operating

Time

between

Oil

Changes

Valve

Clearance

with

lifters

Bled

Down

and

Engine Cold

Firing

Order

Spark

Timing

Spark

Plugs

Spark

Plug

Gap

Fuel

Minimum

Octane

Fuel

Pump

Pressure (Bellanca Only)
Starter
Generator
Magneto

Breaker

Point

Gap

Maximum

Drop Single

Magneto

6A4-150-B3 6-B3

1

6

4.5"

3.5"
335 cu. in.

7:1

2600

150

HP

at

2600

RPM

500

to

600
Clockwise
Clockwise

1 : 1

520°F

Maximum

Spark

Plug

230°F

"

30

to

50

PSI

Maximum

10

to

20

PSI

Minimum

8

Quarts

Free Air

Temperature

Viscosity

Above

40°F

SAE

40

Below

40°F

SAE

20

25

Hours. More

often

if condi-

tions

warrant.

.040"
Cylinders 1

-4-5-2-3

-6

28

Deg rees BTC

Champion

J -

10

.014"

to

.018"

80

Nonleaded

Aviation

7

1

12

PSI

Maximum

12

Volt

15 Amp.

to

25

Amp.

.

019"

to

.021"

200

RPM

9

6A4-165-B3

6

4.5"

3.5"

335

cu. in.

7:1

2800

165 HP

at 2800

RPM

500 to 6

00
Clockwise
Clockwise

1 : 1

52

0°F

Maximum

Spark

Plug

2

30

0

30

to

50 PS I Maxi"

mum

10

to

20

PSI

Minimum

8.8

Qua rts

Fr

ee

Air

Temperature

Viscosity

Above

40°F

SAE

40

Below 40°F

SAE

20

25

Hours. More

often

if

condi-

tions warrant.
.04

0"

Cy

li nder

s 1-4-5-2-3

-6

32 D

egre

es BTC

Cha

mp ion

J-

l 0

.0

14"

to

.018

"

80

Nonleaded Av

iation

7

1

12

P

SI

Maximum

12 Volt

25

Amp.

ot Spe cified

2

00

RPM

VI

- TABLE

OF

LIMITS

AND

TOLERANCES

Desc ripti

on

of

Limits

Cra

nkc

ase

& T

hr

us t

Wash

er

Dowel

Thrust

Was

her & Cr

ank

case

Dowel

Crankcase

Half

& Dowel

Crankshaft Bus

hing & Crankshaft

Crankshaft End

Clearan

ce

Co

nnecting

Rod Bushing &

Crankshaft

Connecting

Rod &

Bol

t (Diam.)

Co

nnecting

Rod Side

Clea

ran

ce

Crank

cas

e &

Mounting

Bra

ket

Dowel

Mounting

Bracket

& Cr

ankcase

Dowel

Camshaf

t Bushing &

Camshaft

Camshaft End Cl

eara

nce

Crankshaft

Gear & Crankshaft

Cam

sha

ft

Gear

& Ca

msha

ft

Cr

ankshaft

&

Camshaft

Gea

rs

(Backlash)

Cr

ankshaft & Magneto

Dr ive

Gear

Hub

Cranksh

aft Run

Out

Ma

in &

Crank

Journ

al

Fillet Radii

Cra nksh

aft

& Dowel

(Flange)

Piston

& Piston Pin

(Hand

Push Fit

with

Piston

at Room

Temperature

)

C

onnecting

Rod & Piston Pin

Piston Pin &

Plug

C

ylinder Liner

Exte

nsion Below

Cylinder

Flange

Cylinder

Barrel &

Piston

Pin (End

Clear

.)

Cylinder Barrel & Pi

ston

(Skirt)

Cylinde

r Barrel &

Piston (Top

land & lands

between

grooves)

Piston Ring

Gap

(All Rings)

Piston

& ,Top Piston Ring (Side

Clearance)

Piston &

2nd

Piston

Ring (Side

Clearance)

Pi

sto

n &

3rd

Piston

Ring (Side

Clearance)

Bushing &

Valve Rock

er Pin

Mfg.

Min.

.

0008T
.00lT
.

OOOST

.002l

.

008
.001Sl

.000Sl
.008
,OOOST
.OOOST
.001Sl
.006
.00lT
.OOOST
.004
.002T

.125
.0015T

.0000
.0007L
.000Sl
.

500
.015
.002l

.028L
.013
.00SSl
.0035l
,002l
.002l

10

Mfg

.

Max.

.0017T

.OOST
.001l
.

004l

.

020
.0034l
.

002l

.014
.001l
.

00ll
.002Sl
.010

.002T
.002T
.012
.0038T

.002
.140
.003T

.

0012

l
.002Sl
.51S
.033

.0035l

.

030l

.023

.007L
.005l
.

003Sl

.0035L

Max.

After Wea r

.004l
.010l
.001l
.0

06l

.026

.00

55L
.002l
.018l
.002l
.002l
.004l
.014l
.00lT
.OOO

ST
.016
.002T
.004

.00lT

.OO

OSl

.0

02l

.004l

.O

SO

.007L

.036l
.040

.009l
.007l
,005Sl
.007L

Va

lve Rock

er

Support (Stamped) & Val

ve Rocke

r Pin

Valve

Rocker

Support

(AI. Block) &

Valve

Rocker

Pin

Valve Rocker End

Clearance

V

alve

Guide & Cylinder

Head

(Early Engin

es)

V

alve

Guide & Cylind

er

Head

(la

te

Engines)

Valve

Guide & Intake

Valve

V

alve

Guide

& Exh

au

st Valv

e

C

ylinder

Head

& In

take

Valve

Seat Insert

Cyl

inder

Head & Ex

haust

Valve

Seat

Inse

rt

Val

ve

Lifter

& C

ran

kcase

Oi I

Pump Gea

r & Sh a

ft

Oi I

Pump

Drive Sh

aft

& Pum p Body

Oil

Pump Drive Gears & Shaft

Oil P

ump Sta t

ionary

Sha

ft

& P

ump Body

Oil Pu

mp

Driv

en

Gea

r &

Shaft

Oil Pu

mp

Gea

rs & Pu

mp Body

Oil Pu

mp Gears (Backlas

h)

Oil

Pump

Drive & Driven (

Back

lash)

Mag.

Drive G

ear Hub &

Gea

r

M

ag

. Drive Gea

r H

ub & Tach.

Dri

ve Gear

M

ag. Driv

e & Driv

en Gears

(Backlash)

Mag. &

Mag.

Adapt

er

Mag.

Driven

Gear

& Ma g

net

o, Driven

Gear

Hub

S

tarter Gear

Hub & Crankshaft

Tach. Drive & Drive n

Gear

s (Ba ckl

ash)

Ta

ch. Drive Connector & Ta

ch. Driven

Gear

Tach.

Connector

Sleeve &

Tach

. Drive

Connector

Tac

h.

Conn

ector

Sleeve & Tach. Drive H

ousing

Gen

erat

or Gear & Hu

b

G

enerat

or

Drive & Driven Gears

(Backla sh )

C

rankcase

& Dowel (Timing

Case)

Timing

Gear

Case & Crankcase

Dowel

T

iming

Gear Ca

se & Mag. Adapt

er

Tim

ing Gear

Case & Starter

Timing

Gear Case

& Ge

nerator

.001T
.001T
.003

.003T

.002T

.0

02Sl

.00

2Sl
.004T
.

00

4 1T

.001 l
.

OOOST

.00l

l

.

0000

.OOO

ST

.

000Sl

.002

l

.

004
.004
.002T
.OOOST
.006
.000Sl
.00

0Sl
.004T
.001
.001 2T
.

OOO

ST
.001Sl
.000

6l
.006
.0

00l

T
.000lT
.00

0Sl

.00

0Sl

.0

00Sl

.00lS

l

.

000Sl

.008
.004T
.003T

.

004

3L

.0043l

.00

6T
.006 1T
.00

2l
.002T
.

00

2Sl

.0

0l

ST

.001ST

.00

2l
.007l

.008
.008
.003ST
.

002

T

.010
.0045L
.

00

25l

.0052T

.003

.00

2T

.0

0l3T
.003Sl
.00

26l

.

010
.0013T
.0013T
.

004

Sl

.00

4Sl

.004SL

.0

02

SL
.001Sl
.00

8l

.0

02T

.

002

T

.

006

l

.

006l

.0

03T
.003T
.004l

.

OOO

ST

.004L

.

000

.

000

.0

04l
.010

l

.01

5

.01

2

.0

02
.0005T
.0 16

.0

04l

.003T

.

01

0l
.001T
.OOOST

.008l
.0

04l

.

016

.001 l
.001 L

.008l
.008l
.008l

11

VII-

RECOMMENDED TIGHTENING

TORQUE

VALUES

NAME

Stud
Stud
Stud
Stud
Screw
Screw

Screw

Nut
Nut
Nut

Standard

SIZE

OF

THREADS

Studs,

Screws

6'

1/4-20

5/

16-18

3/8-16

7/16-14

1/4-20

5/16-18

3/8-16
1/4-28

5/16-24

3/8-24

Nuts

TORQUE

VALUE

FOR

TIGHTENING <INCH-LIS.)

MINIMUM-MAXIMUM

25-60
50-90

75-110

95-195
60-75

105-

120

120-145

60-75

1

10-130

300-360

Special Applications

Oil Pump

Attaching

Screw

1/4-20

55-60

Crankcase

Cover Screw

5/16-18

Oil

Pan Holding Screw

5/16-18

60-75

Cylinder Hold-Down

Nut

3/8-24

240-300

Cylinder Hold-Down

Nut

7/

16-20

300-330

Crankcase

Tie Bold

Nut

5/

16-24

Camshaft

Bearing Stud

Nut

5/16-24

145-180

Mounting Bracket Stud

Nut

5/16-24

Distributing

Zone

to

Manifold Bolt

5/16-24

Starter

Mounting

Nut

3/

8-24

145-180

Spark

Plugs

14MM

180-240

Magneto

Nut

7/16-20

240-300

VIII-OVERHAUL

PERIODS

AND

PERIODIC

INSPE

TIONS

TOP OVERHAUL

MAJOR OVERHAUL

The

time

at

which a top overhaul

will

be neces-

No

definite

period

is

set

for a major overhaul.

sary

will

vary considerably with

the

type

of

opera-

Most engines

will

require

an

overhaul

after

600

to

tion

and

the

care

taken

of

the

engine

generally.

700

hours

of

operation.

The

periodic inspections

Proper i'1spections performed

at

the

specified

and

general

operating

characteristics

will

indica

te

periods (See inspection check list)

will

reveal

the

the

necessity

of

a major overhaul if one

is

needed

necessity

of

a top overhaul.

If

a top overhaul

is

not

sooner.

required

at

300

hours,

the

rubber

magneto

and

generator

drive shock absorber cushions should be

inspected

at

this time. Any worn cushions should

be

replaced.

12

----

------

-----------

----

------

-----

--

------

------

----

----

---

----

----

--------

------

--

----

--------------------

---

----

--

---------

--------------------------------

--

PERIOD C NSPECTIONS CHECK LIST

COVERING MODEL 6A4-150-B31, 6A4-150-13

and

6A4-165-83 ENGINES

Propeller

Blades

(Visual)

x

Ignition

Wires & Terminals

(Visual)

x

AccessibJe

Nuts

, Cop Screws & Fasteners fV;suaJ) x

Fuel

and

Oil Level

x x

x x

--------------

-

-------

--

-

Engine

Controls

(Free

Movement

& Full

Range)

x

x

x

x

--~-------------------

------------------------

--

Oil

Leaks

x

x

x

x

Fuel

Leaks

x x

x

x

Propeller

Bolts

(Check

for

Tightness & Safetying)

x

x

x

I~nition

Wires &Terminals

(Check

for

Tightne~-C~hafing&S~~~ere

d

ss,~ ~~~-

~~o~--

~----

------------

-------~

Connections-Clean)

x

x

x

Accessible

Nuts,

Cap

Screws & Fasteners

(Check

for

Tightness & Safetying)

x x

x

Engine

Controls

(Check

Free

MovemEmt, Full

Range & Linkage

System,

Lubricate)

x x x

Oil

Change

(More

Often

if

Operating

Conditions

Warrant)

x x x

------

--~------------

-----------------------

~--

---

Propeller

Track

x x

Exhaust

System

(Check

for

Leaks & Tightness)

x

x

x

Ora

in

Plugs & Fi

Ifer

Cops

(--=C:-=-h

-ckfo

n

--- --i -

&

sk

---

-------------

----------

-

e

----,

~-r---=T:-=ig=-:-h-t

-ess, ---;:;S~a-;;-fe

ty-,-ng

------;;;

-

--=G~a

----,

;--et

Condition)

x x

x

Cooling

Air

Baffles

(Check

for

Obstructions & Leaks)

x x x

Filters,

Strainers & Sumps

(Inspect & Clean)

x x

x

Compression

Check

(Check

all

cylinders

by

pulling

through

Propeller)

x

x x

--~

~~-~7-

--

_7~--~~~

--

--------------

--

--

--

--

Manifold

Equalizer

Pipe

Hose

Connection

(Check

condition

of

Hose

and

Tightness

of

Clamps)

x x x

Magneto

Breaker

P~o-in

ts----:

&

::-:-

---ibut-r

-----;-

(-=C

:-;:--ck

co-

nd---;-:-it

--=-

ion

of

rotor

&

-~

:;;--;::

Distr-----::-

--o-

he-

=-------

-

Distributor & Point

Condition & Gap)

x
x

Magneto

Timing & Synchroniza

_t_io_n

_________

~~~~

__

~~~~

__

~~

__

_________

________

_

Spark

Plugs

(Clean & Regap)

x

~

--------

-~

------~

----

--------~----~~

--

Cylinder

Fins

(Check

for

Breaks--Clean)

x

--

-

---

,

Carburetor

(Clean & Drain)

x

Fuel Lines

(Check

for

Chafing-Blow

Out

)

x

------

--~

--------

---~------

-

Engine

Mounts

(Chec

for

Tightness & Wear)

x

Generator

(Check

Connections,

Charging

Rate)

x

~---

~

~~

--

-----

---~----

~

--

Starter

(Check

Connections & Operation

of

Bendix

Drive)

x

Valve

Clearance

(Check & Adjust)

Every

200

Hours

Minimum

Magneto & Generator

Shock

Absorber

Drives

(Replace

worn

absorbers)

Every

300

Hours

Minimum

------

--------

-----~~--

---

----

~--

13

x

IX -ENG

INE LUBRICA ION

T

he primary

purpose

of

engine lubrica t ion is to

prevent met

a l-to-meta l conta ct between moving

par

ts. T

he

friction

accompany

ing

such meta

l-t

:>-

metal contact would

result in a loss

of

power, rapid

wear, a nd a

temp

erature

rise th

at might

cause part

s

to

fa

il. The a

ction

of the oil

is

to co

at

each met

a l

surface with a film. Be tween t

he

two films, other

l

ayers

of

the

oil sli

de

a long ov

er

each

other, t

hus

rep

lacing the high

frict

ion

of

metal-to-m

eta l c

on-

tact

by the low

inter

na l fricti

on

of

the

oil.

I n the process

of

circulating th

rough

the eng

ine,

oil absorb s he a t from

the

va rious

part

s. Most

of

this heat

is

dissipated

when the oil flows

through

the

oi

I coole

r.

It

is

ver

y im

port

ant that

an oil

of

the

proper

vis-

cosity

be used, since using too

heavy

an

oil will

impair

ci rcula ti

on

and insu

fficient

lubricati on w

ill

resu lt.

Operating

condition

s will control the period

be-

tween oil chang

es; however, t

he maxim

um

time

s

hould

not exce

ed

25

hou

rs.

Th

e S.A

.E.

lette

rs on a n oil co

ntainer do not

det

erm

ine the quali

ty of the lubric

ant.

The

refiner's

rep

utatio

n is y

our

best

guide

to the qua lity

of

the

product.

Pr

op

er lubrication

of y

our

engine should

be giv en

your most

ca reful a

ttention since improper

lubrica-

tion is evid

ence

d only after the dam

age

to

the

engi ne

has

occurred

and

is often very

cost ly. Using

the

proper

grade of

a good lu

bricant is cheaper

than

repa ir bills.

We

str

ong

ly

recommend

that

our

specifi

cation

a nd service

instructions

be strictly

followed.

ENGIN E

OI

L SPEC IFICA

TIONS

FOR MODEL

6

A4-150

-B3 A ND 831 AND

6A4-165-B3

ENG IN

ES

S

AE

40 when

free

air

temperature

is 40°F or

above.

SAE 20 when free a ir tem

perature

is

below 40°F.

x - CRANKCASE

The cra

nkcase is

built

in two h

alv

es of

high-

s

trength a luminum

alloy. (See Fig. 3. ) Each

crank-

ca

se half cont

ains

three

cylinder mounting p

ads

and

two e

ngin

e mount brack

et pads.

The left case

half

also

includes pads for the o

il

pump a nd oil

b

y-pass plat

e.

The

cran

kca

se whe n assembl

ed

as a unit

has a top

machined

face

to

take

a

cov

er

and a bottom machined

fac

e on which

the

o

il

pan

is

mounted. On

the model 6A4-

150-B3

a

nd

B31

eng

ines, a n oil seal is obtain

ed

between the

halves

at

the

nose

section

by two .135"-.14

5"

di-

ameter

synthetic

rubber packing

str

ips. Thes

e p

ack

-

ing

strips

fit

into grooves

mac

hin

ed into

the ma

ting

face

of

the

right

crankcase

half. The

se st rips

are

longer

than

the

grooves so

that they must

be

t

rimmed

to

length

after the

crank

case

is assembled

with

the

cra

nksh

aft

a nd camshaft. Ex

treme care

should

be taken

to

trim the ends

of t

he packing

strips absolutely flush w

ith

the face of

the

crank

-

ca

se.

This

is

partic

ula rly important

in t

he

nose oil

seal reces s, as

an

oil

leak

wil

l oc

cur

if t

he

packing

protrudes a t this loc

ation

. The model 6A4-

165-83

engine

does

not have

the rubber packing strips

be-

tween the c

ase

ha lves, and the packing st rip grooves

a re omit

te

d. An oil sea l

is obt

ained

on this

model

by

si

lk threads plac

ed

on the rig

ht

crankca

se half

in

the same positi

on

as the

grooves were located

in t

he othe

r models.

Fig.

46

shows t

he loc

ati

on of

these grooves. The threa ds a re

also trimmed flush

wi

th the

cra

nkcase fa

ces

oft

er

assembl

y. It is im-

po rtan t

that

the small rubber po cking rin

gs

at the

through

st

uds

be

in place b

efore

the

case

is re-

assembled. On

the

mod

el 6A4

-165-

B3

engin

e, it is

ne

cessa ry to put a sma

ll fiber was

her

under the oil

cro

ss-ov

er passage sea l rin g

to

pre

vent

it from fail-

ing in

to

the p

assa

ge. I t is advisable

to

ho ld the oil

sea

l p

ock

ing strips and rings in p

lace

with

a lig

ht

coot of

cup

grease

duri ng assembly.

7

6

3

FIG. 3.

I.

Main

Bearin

g J

ournal

2.

Propeller

Shaft

Bearing

Journal

3.

Nose Se

al

Adapting

Recess

4.

Engine

Mounting

Bracket

5.

Cylinder

Hold-Down

Stud

6.

Top

Crankcase

Cover

Mounting

Pad

10

Crankcase

7.

Rear

Through

Tie

Stud

8.

Crankcase

Assembly

Stud

9.

Top

Front

Through

Tie

Stud

10.

Front

Through

Tie

Stud

1 1.

Thrust

Washer

Mount-

ing

Pad

12.

Camshaft

Through

Tie

Stud

14

4

FIG.

4.

Crankshaft

and

Main

B arings

10

The

crankcase

on

the

model

6A4-165-B3

engine

has

drilled oil passages

and a mount

pad

to

take

a

propeller control valve'. This

pad

is

on

the

left front

of

the

crankcase

just

above

the

engine

mount

bracket.

The

two halves

are

joined internally

bya

series

of

six special

heat-treated

3/

8"

studs

located

at

the

main

bearing journals

and

four

heat-treated

5/ 16"

studs

located

at

the

camshaft bearing

jour-

nals.

Castle

nuts

safetied

with

cotter

pins

and

flat

washers

are

used on all internal

studs

. Two 3/

8"

studs

at

the

front

bearing

journal

and two

3/

8"

studs

at

the

rear

bearing

journal,

as well

as

one

5/

16"

stud

at

the

front

top protrude

through

the

right

crankcase

half. These five

studs

are

secured

externally using

flat

washers

and

elastic

stop

nuts.

Three

5/

16"-24x7-3/ 16"

hex

head

bolts

are

in-

stalled along the

top

of

the

case,

as

well as

three

5/

16"-24

x 1-3/

8"

hex

head

bolts installed

at

the

front

end

of

the

engine

straight

through

both

crankcase

halves. Plain 5/ 16" washers

are

used

under bolt

heads

and

under

the

specified

elastic

stop

nuts.

When

assembling

the

crankcase

halves, observe

that

the

aligning dowels

fit

in their respective holes

and

draw

up

the

crankcase

assembly

nuts

evenly.

XI-CRA

1

5

Wh

en

assembled with mati ng halves,

the

crank

-

sh

aft main bearing

hole

is

bored to 2,406" to

2.407"

and the

camsha

ft beari ng hole is bored to

1. 1245"

to 1

.1250

".

Each

of

the

six cylinder pods are s

tudded

at the

proper locations

as

follows: Four studs, 7/ 16-

14

NC

stud

end, 7/ 16-20-NF-

3 nut

end, dr

iven to a h

eight

above

pad

of 1

-1

/ 8". Four studs 3/ 8-1 6 NC

stud

end, 3/

8-24

-NF-3 n

ut

end, driven to a height

above

pad

of 1-1/

16".

One

pad

is loc

ated

at

each of

the

four low

er

out-

side corn e

rs

of

the

cra nkc

ase

to

acc

omm

odate

the

engine

moun ting brackets. Four dowels

are

located

in

the

case

to align

the

brackets, one do

wel

for each

bra

cket. On

the

early engines, the

brackets

a re

secured to

the case by

mea

ns

of two

studs.

5/

16-18 x 7/

8" hex

hea

d cap screws are used on

the

later

engine . Some engi

ne

models u

se

flat

washers

and

drilled he

ad

hex

ca p scre

ws

safetied

with lacing wire. On some engines

the low

er righ

t-

hand

bracket

is

of

special desi

gn with a p

ad

for

fuel

pump attachm

ent.

When

the

crankcase

is

disasse mbled a t engi

ne

overhaul, it

is

important

that

all plugs be removed

and

the

oil galleries and o

il

pass

ages

be thorough ly

flushed

out

before reinstalling

the plugs.

KSHAFT

1. Cr

ankshaft Gear

2.

Center Main

Journal

3.

Connecting Rod Journal

4.

Front

Main

and

Pro-

peller

Shaft Journa

ls

5.

Re

ar Main

Journa

l

6 .

Re

a r Main Bearing

7.

Cente

r M

ain Bearing

8. Fro

nt Main Bearing

9. Propeller Sha ft Bearing

10.

Pr

ope ller Bolt Flan

ge

Bush ing

15

The

crankshaft

is a one

piece, six throw, alloy

steel forging,

heat

treated

and

designed

to

with-

stand

high stress.

It

is

drilled f

or lightness

and

to

supply lubrication to all

the

beari ngs. (See Fig. 4. )

The

fillets

ground

on

the

crankshaft

have a

.125"

to

.140"

radius on

the

main

bea ring journals

and

connecting rod bearing journals.

These

fillets reduce

the

tendency

toward localization of stress

and

for

this reason it

is

important

that fil

let

specifica -

tions be observed

if

the

crankshaft

is

reground.

Also,

after

regrinding

the

journals, the fillets should

be

shot

peened

according

to

Aircooled Motors speci-

fication # 1 1981 .

CRANKSHAFT BEARINGS

The

crankshaft

is

supported

in

the

crankcase

by

five

split

steel-backed,

main

bearings

of

.0770"

to

.0775"

wall thickness

after

plating

. (See Figure

4.)

The

bearing shells

have

0 crush fit to secure

them

in

the

crankcase

bore

and

insure rigid

support

for

the

crankshaft.

The

five bearings

are

referred to by

number

with

the

# 1 bearing

at

the

rear

of

the

engine.

It

is

essential

that

the

bear

ing shell halves

containing

the

oil holes be

assembled

so

that

they

motch

the

oil

passages

in

the

left

crankcase

half.

Figure

No.4

shows

the

#4

main

bearing

with a

single oil groove. This

bearing

on

the

model

6A4-165-B3

engine

has

an

additional

oil

transfer

groove

to

provide a

passage

for propeller control

oil. This bearing having

the

oil

transfer

groove

will

. be suppl ied for service

replacement

for

the

#4

and

#5

bearings

on

all model engines referred to in

this

manual.

The

crankshaft

end-play, when

the

crankshaft

is

fitted

in

the

crankcase,

is

.008"

to

.020"

and

is

controlled by two split

bronze

thrust

washers lo-

cated

and

doweled to

the

front

and

rear

sides of

the

crankcase

web

of

the

front

center

main

bearing

support

in

both

crankcase

halves.

The

end

play

should be

checked

with

both

crankcase

halves

sepa-

rately

as

well

as

after

assembly

to

make

sure

that

the

.008"

minimum

clearance

is

obtainable.

Thrust

washers

must

be replaced in pairs

as

slight

varia-

tions in thickness exist between

different

pairs.

The

crankshaft

main

bearing journal

diameter

is

ground

to

2.249"

to

2.250"

and

the

connecting

rod

bearing journal

is

ground to

1.9365"

to

1.9375".

When

assembled in

the

crankcase,

the

clearance

between

the

crankshaft

journa

ls

and

main

bearings

is

.002"

to

.004".

Eight bushings with inside

diameter

threaded

3/8"

-24

NF-3

are

pressed into

the

flange

at

the

front

of

the

crankshaf

t for

attaching

the

propeller.

The

.6265"

to .627

0"

major

outside

diameter

of

the

bushing

is

a .

0015"

to

.003"

press fit

in

the

.624"

to

.625"

reamed holes in

the crankshaft

flange.

The

model 6A4-150-B31

has a 5"

diameter

bolt circle

flange.

The

model

6A4-150-B3

and

6A4-165-B3

engines

hqve a

standard

SAE-3 5.25" bolt circle

flange. Two

Woodruff

key

seats

3/

16

by 1-1/

8"

are

cut

in

the

rear

main

bearing journal extension

for

att

aching

the

crankshaft

gear, starter

gear

and

accessory drive gear.

The

crankshaft

runout,

token

with

the

shaft

sup-

ported on its main

bearing

journals, should

not

exceed

.002"

total

indicator reading.

The

crankshaft

of

the

6A4-165-B3

engine

is

drilled

at

the

front

main

journal to provide a pas-

sage

for propeller

actuating

oil from

the

crankcase

to

the

hollow propeller

shaft.

The

aluminum

plug

closing

the

end

of

the

propeller

shaft

should

not

be

removed

except

possibly

at a major

overhaul when

it

is

desired

to

thoroughly

clean

the

shaft.

This plug

is

assembled with a press

fit

in

the

shaft

and

is

safetied

with a

set

screw. If

the

plug

is

ever re-

moved, it should be replaced by a new

part,

as

the

old one

is

usually

damaged

by removal.

The

1/8"

pipe plug, which

is

installed in

the

center

of

the

aluminum

plug, should also never be removed ex-

cept

when a hydraulically

actuated

propeller is

installed

on

the

engine.

The

hollow propeller

shaft

carries

engine

oil which

will

escape

if

either

plug

is

not

in

place

during

engine

operation.

The

crankshaft

flange

has

the

following

mark-

ings on

the

rim

of

its outside

diameter:

"No.

1

U.D.C.,

24

and

28

degrees."

The

No. 1 U.D.C.

mark,

when in line with

the

center

line of

the

crank-

case

at

the

top

of

the

engine, refers to top

dead

center

of

No. 1 cylinder.

The

28

degree

mark

is

used for ignition timing on

the

model 6A4-1 50-B3

and

B31

engines

and,

when

01

igned with

the

crank-

case

center

line,

refresents

28

degrees before top

dead

center

on No. cyl

inder

when

on

the

compres-

sion stroke.

The

32

degree

mark

is

used for igni-

tion timing

the

6A4-165-B3

and,

when al igned

with

the

crankcase

center

line, represents

32

de-

grees before

top

dead

center

on

No.1

cylinder when

on

the

compression stroke.

Before installation

at

the

factory, every

crank-

shaft

is

100% magnetically

inspected

and

tested

for dynamic

and

static

balance.

CRANKSHAFT OIL

SEAL

!

4

FIG.

5.

Crankshaft

Oil Seal

1.

Crankshaft

Oil

Seal

3.

Oil

Seal

RetainerWasher

Spring

4.

Retainer

Washer

2.

Crankshaft

Oil

Seal

Attachment

Screw

Packing

A spring loaded all seal

is

installed

in

the

3.248"

to

3.250"

recess in

the

front end

of

the

crankcase,

formed by

the

assembly of

the

two

crankcase

halves. (See Fig. 5. )

The

free length

of

the

spring

itself

in

the

open position should

measure 7 -1 / 8"

to

7-1 / 4".

Be

sure

to

specify

the

correct

part

number

when ordering

the

seal. (See Fig. 5-1.)

The

spring

side of

the

seal

is

towards

the

rear

of

the

engine

and

a light

coating

of

sealing compound

is

applied

to

the

outside

surface

of

the

seal before pressing

the

seal into place.

The

split

in

the

seal should be

located

approximately

45

degrees

from

the

crank-

case

parting

line

to

insure

that

no oil

seepage

will

occur where

the

seal ends come together.

The

seal

should be

topped

into position evenly to

prevent

distortion

and

insure proper

seating

in

the

crank-

case

bore. A

split

retainer

plate

is

used

to

hold

the

seal in position. This

plate

is

attached

to

the

front

end

of

the

crankcase

by

means

of

two

1 /

4"

-20

x 1/

2"

hex

head

cap

screws

and

two 1 /

4"

shakeproof

washers.

16

X

II

-

CAMSHAFT

FIG.

6.

Camshaft a

nd

Bearings

1. Ca

mshaft Gear

2. Fuel Pum p Cam

3. Va lve A

ctuating

Cam

The camshaft inc

orporate

s six

intake

and

six

exhaust

lobes

and

has

four beari ng journals. (See

Fig.

6.)

The

bearing journals

are

ground .9985"

to .

999

",

and

the

journal

clearance

with

the

bear-

ing

is

.0015"

to

.0025".

The

permissible

camsh

aft

end ploy when assembled in

the

crankcase

is

.006"

to .

010".

The

end

ploy should be checked with

each

cran

kcase

half

separately,

as

well

QS

after

assem-

bly,

to

mak

e sure

that

the

.006"

minimum clear-

ance

is obtainab

le.

The

permissible

camshaft

runout

is

.00

2"

total indicator reading. This read-

ing

is

taken

at

the

cen t

er

of

the

shaft,

while being

supp

orted on

the

bearing

journals.

The

total thickness

of

the

split

camshaft

bear-

ing shells

is

.0620"

to

.06225"

when new.

Care

should

be

taken

when reassembling

the

bearings

in

the

crankcase.

I t

is

essential

that

the

bearing

half containing

the

oil hole

be

assembled

in

the

4.

Camsha

ft

Bearing

Journal

5. Ca msh

aft Bea ring

6.

Oil Pump Drive Gear

l

eft

half

of the

cra

nkcase so

that these oil hole

s

wi

ll

mate

with the oil

passages

in

the

case.

A ca

mshaft

from

the

6A4-150-B3

model should

never be interc

hange

d with

the

camshaft

from

the

6A4-165-B3

model. The

cam

lobe dimensions a re

diffe

rent

on

the

two models. Interch

ang

ing

cam-

shafts

would c

ause

improper func tion of the va lves

and

damage

to

the

valve

operating

parts

.

Both

cast

i ron

and

forged steel

camshafts

have

been

used on t

he

model 6A4-1 50-B3 engine.

The

timing

gear

is

located by a shoulder on

the

steel

shaft.

There

is

no locating shoulder on the c

ast

iron

camshaft,

however,

and the

gear

is

pressed on

to a distance

of

1.034"

to

1 .

036"

from the flan

ge

face. As

the

I.D. of

the

two timi ng g

ears

is differ-

ent,

it

is

necess

ary

to consult

the

Par

ts Book

to

determine

the

prop

er gear

to order for

eit

her sh

aft.

XIII -TIMING

G

AR CASES

The case encl

osing the a ccessory gear

train

con-

sists of two aluminum-a

llo

y castings,

the

front

ti

mi

ng or front

acc

essory case

and

the

rear

accesso

ry

or rear timi

ng

gear ca

se . (See Fig.

7.)

The front case which houses

the

cra

nkshaft

and

cams

haft gears

is attach ed to the re

ar crank

-

case surface by eight

5/16"-

18 x 7/ 8"

and

two

5/1 6

"-18

x 2

-1/4"

hex

head ca

p screws. The eight

sho

rt

scre

ws

use plain

5/16" flat was

hers a nd are
sec ured by lacing wire. The two long screws use
sha

keproof washers. The al ignment

of

this front

housing with the crankca se is

maintained

by two

1/4" x 3/

4"

dowels embedded

in

the rear

crank-

case mating surface.

The rear

case

which houses t

he

accessory

gear

train is fa

stened

to the front case by

ten

1 /

4"-

20 x 5/

8" and two

3/8"-16

xl"

hex

head cap

17

screws. Shakeproof washers

are

used

thr

ougho

ut

on

these

screws. La

ter

model

6AL-150-B3

and all

mod el 6A4-1 65-B3 en gines incorpora

te

two 1/

4"

do

wel

bolts

in place of the two large cap sc rews.

On

th

e older style re

ar

tim ing g

ear

case, a ten-

non

th

at matches a pilot diameter

in

the

front

tim

ing gear case

is

used to ma intain

alignment

in

stead

of

the

dowel bolts

used on the later

engines.

Th

er

efore,

the old

and

new type timing ge

ar

cases

ar

e not int erchangeable. It is important

to

consult

the Pa rts Book

to det

erm

ine the proper

mat

ing

tim ing gear

case

when ordering repla

ceme

nt pa rts.

The

cra

nkcase on all models

will

take

either

the

old

or

the new type timing

gear

cases.

Composition

gaskets

are

used between the

c

rankcase

and

the

front

timing case, as well

as

between the two timing

gear

cases.

\

5

REAR

TIM

ING

GEAR

HOUSING

FRONT

TIMING

GEAR

HOUSING

FIG.

,.

Timing

Gear

Housings

1.

Starter

Mounting

Pod

4.

Rear

Housing to Front

2.

Magneto

Mounting

Pod

Housing

Cop

Screws

3.

Generator

Mounting

5.

Oil Pon

Support

Studs

Pod

XIV -

CONNECTING

RODS

The

connecting rods

are

an

alloy

steal

forging,
magnetically inspected before being assembled on
the

cranksh

aft. (See Fig. 8,) They

are a matched

we

ight

assembly

and

are

stamped

on

the

bolt

bosses

in

relation to

their

cylinder position on

the

crankshaft

.

When

reassembl ing

the

rods on

the

crankshaft,

it

is

important

that

they

be

returned

to

their

orig-

inal position.

The

rods

are

located

in

numerical

order with

# 1 rod on

the

crank

throw which

is

ne

arest

the

gear

end

of

the

crankshaft

and

#6

rod

is

on

the

throw which

is

nearest

the

flange

end

of

the

shaft.

The lowe

r bushing

is

of

the

steel-

backed

split

type and

the

halves

are

interchangeable.

When

assem bling

the

lower

cap

to

the

rod, cylinder posi-

tion numbers on

the

bosses should be on

the

same

side of th e rod. The # 2,

#4

and

#6

rods have

the

finished reli

ef

surfac

e on

the

top

cap

towards

the

front

of

the engine

while

the

reliefs on # 1,

#3

FIG.

8.

Connecting

Rod Assem bly

and #5 rods face

the

rear

of

the

engine. It

is

im-

p

ortant

at

asse mbly to see

that

the

tongue

on

the

1.

Connecting

Rod

ond

4.

Lower Cop Co

nnecting

back of

the

bushing fits

the

slot provided

in

the

Upper

Cop

Rod Beari

ng

conn

ecting

rod to

prevent

binding or movement

of

2.

Connecting

Rod Bolt

5.

Connecti ng Rod Lower

the

bushing halves when installed.

The

wall

thick-

Co p

3.

Upper

Cop

Connecting

ness of

the

bushing

is

.06105"

to

,06150".

The

Rod Bearing 6.

Nut-C

onn

ecting

Rod

bushings are a crush fit when assembled

in

the

Bo

lt

18

connecting

rods.

When

assembled

to

the

crank-

shaft,

they

have a

cleardnce

of

.0015"

to

.0034"

on

the

crankshaft

throws.

The

connecting

rod

cap

is

assembled

to

the

rod

by two alloy

steel,

3/

8" -24

NF rolled

thread,

upset

head

bolts.

The

bolts

are

installed with

the

head

end

toward

the

piston pin bushing.

The

two 3/

8" -24

slotted

nuts

must

be

drawn

up

evenly

and

safetied

by two 3/

32"

x 3/

4"

cotter

pins.

The

side

clear-

ance

between

the

connecting

rods

and

the

crank-

shaft

cheeks

is

.00

8"

to .014".

Two holes

are

drilled in

the

connecting

rod

at

on

angle

of

36°

to

the

vertical

center-line.

These

holes

index with two holes in

the

bearing

bushing.

The

xv - P

STON,

PISTON

The

permanent

mould

cost

aluminum

alloy

pistons

are

of

a special design, which controls

ex-

pansion

to

a high

degree,

permitting

a close fit

between

piston

and

cylinder wall. (See Fig. 9-1. )

This

feature

provides for long cyl inder, piston

and

ring life

and

eliminates

piston

slap.

The

clearance

between

the

piston

and

cylinder

wall,

taken

at

the

bottom

of

the

piston

skirt,

is

.002" to .0035"

and

token

at

the

top

of

the

skirt,

just

below

the

slot,

is

.003"

to

.0045". (See Fig.

10.)

This

clearance

can

best

be

taken

by using a

long

feeler

gauge,

which will

reach

the

length

of

the

cylinder liner.

The

piston should

be

installed,

without

the

rings,

in

its normal

running

position

within

the

cylinder

and

the

clearance

taken

at

the

top

and

bottom

of

the

cylinder bore A .002" feeler

gouge

should

indicate

no

drag

when

checking

piston

clearance.

FIG.

10.

Checking

Pinon

Cleoronce

19

holes

permit

oil

to

spray

upward a

gain

st

the cyl-

inder walls

and pist

ons. To lub ricate

the pi

ston

pins

and

piston pin

bushings, thr

ee

holes

are

drilled

in

the

upper

end

of

the conne

cti ng rod and piston

pin bushing.

The

piston pin

bushing

is

a press f

it

in the

1.

0375"

to

1.

0385"

hole of the con

nect

ing rod.

After

installation,

it

is

bored

to

.9847" to .9849".

The

bushing

must

be insta

ll

ed

with the three

drilled holes indexing with

the

thr

ee

holes in t

he

connecting

rod

upper

boss.

Clearance

betwe

en the

piston pin

and

bushing

is

.0007" to .0012". T

he

two bores

of

the

conne

cting rod must be parallel.

PINS

AND

RINGS

- - I

2

-··

----

-

~~~~

Piaton

ond

Piston Pin

1.

Piston

3 . Pis

ton

Pin

Plug

2..

Piston

Pin

If

at

any

time

the

piston with rings installed

should

be

inserted

by

hand

in

the

cyl inder

bor

e,

do

not

push

the

piston

into

the

top

of

the

cylinde r

as

the

top

groove piston ring will

expand

above

the

upper

rim

of

the

cylinder li

ner

and lock the

piston

in

the

combustion

chamber

.

The

ring groove widths

are

as

follows : T

op

groove - ,099"

to

,100", middle groove - .097"

to

.098",

bottom

groove - ,1885"

to

.1895",

The

diameter

of

the

piston pin holes in the

piston

is

.98415" to .9840".

Pistons

are plat

ed all

over

with

the

exception

of

the pis

ton

pin holes.

The

pistons

are

stomped

for loca

tion

on the

bottom

of

the

piston pin boss. The numb er corr

e-

sponds

to

the

cylinder location

on the

engine

in

which

they

are

installed.

PISTON

PI

N

The

hollow piston pins are

of all

oy stee

l,

heat-

treated

and

magnetic

all y inspected. (See Fig.

9-2

.)

They

are

of

the

full f

loating

type and a re a palm

push

fit

in

the

piston

at

room

tempe

ratu

re (70° F).

They

are

finished inside

to

a dia me

ter

of

.619" to

.620"

and

ground

outside

to a diamet

er

of .9

838"

3

to

.9840".

The

piston pin

ends

must

De

square

with

their

axis within

.001"

total

indicator

reading to

insure proper

bearing

surface

for

the

end

plugs

and

assembly

end

clearance.

Two

aluminum

plugs

are

installed in

tne

ends

of

the

piston pin.

The

out-

side

diameter

of

the

plugs, where

they

fi

t inside

the

pin,

is

.6175/'

to

.61

85"

.

The

piston pins, when installed, give

the

piston

pin with

buttons

assembled

an

end cle

arance

in

the

cylinder bore

of

.015"

to

.033".

This

clearance

is

best

checked

by using a feeler

gauge.

Install a

piston pin

in

the

piston

and

insert

the

piston

in

the

cylinder bore

far

enough

to

permit

checking

the

piston pin

end

clearance

with a piston pin

button

against

one

side

of

the

cyl inder bore.

PISTON

RINGS: (FIG. 12)

FIG.

12.

Pist~n

and

Rings

1.

Top

Compression Ring

3.

Oil Control Ring

2.

Middle

or

Scraper

4.

Piston

Compression Ring

The

piston

is

provided with

three

ring grooves

to

accommodate

three

Perfect

Circle piston rings.

The

lower groove

has

holes drilled

through

the

piston wall

to

the

inside

of

the

piston for oil return.

The

top

ring

is

a compression ring with a width

of

.0930"

to

.0935".

It

has

an

undercut

on

the

inside

diameter

of

one

face,

around

the

circum-

ference

of

the

ring.

The

ring

must

be installed

with its

undercut

facing

the

top

of

the

piston. See

Fig. 1 1 for

the

diagram

showing

the

proper ring

positions.

1--~

2--~

3

:LJ

FIG.

11.

Piston Ring

Installation

1. Top Compression Ring

2.

Middle Compression­Scraper

Ring

3.

Oil

Control Ring

The

middle ring

is

a compression

scraper

ring

with a width

of

.093

0"

to

.0935". 1 ts

undercut

is

on one

edge

of

the

outer

circumference. Thi s ring

must

be installed with

the

undercu

t faci ng

the

bottom

of

the pist

on. This

is

important

as

reversing

the

ring

ot

installation

will

caus

e it

to scrape the

oil towa rd

the

combustion chambe

-r,

resulti ng in

high oil

consumption

and

fouled

spark

plugs.

The

lower groove ring

is

an

oil control ring of

the

slotted

type, with a width

of .1860"

to .186

5".

It

may

be installed in

any

position in the

low

er

groove.

The

piston ring

gap

for all

three

rings, when

measured

in

the

cylinder, should be .

013"

to

.02

3".

(See Fig.

13

for

method

of

measurement. ) The

top

ring

has

a side

clearance

when installed in

piston groove

of .0055"

to

.007".

The

center

ring

has

a side

clearance

of

.0035"

to

.005",

and

the

bottom

ring,

.002"

to

.0035".

When

the

pistons

are

installed on

the

engine,

the

ring

gaps

are

stag-

gered

in

relation

to

each

other,

before installing

the

cylinders.

FIG.

13.

Ring Gop

Clearance

20

XVI-CY

INDER

ASSEMBLY

Franklin cyl i

nde

rs

are

one -piece

aluminum

alloy

s

and

castings, incorporating deep, closely

spaced

fins to insure

ample

cooling

under

the

various

op-

erating

conditions

of

the

engine. (See Figs.

14

thru

17.)

The

piston bore

of

the

cylinder

is

fitted

with a nickel-iron liner which

extends

the

full

length of

the

cyl

inder barrel section

and

projects

.500

to

.51 5 be.low

the

cylinder flange of

the

cylinder casting. The liner

is

positionea by a lock

pin which

is

held solidly

in

place by two lock screws.

(S

ee

Fig. 14-3,

4.)

To

prevent

oil leaks,

the

lock

pin

and lock

screws

are

coated

with a liquid joint-

ing compound

at

assembly.

The

lock pin or lock

screws should never

be

removed;

replacement

is

necessary only when install ing a new Iiner. On
initial assembly,

the

lock pin

is

installed before

the

final grinding

and

honing of

the

cylinder barrel

operation,

and

is,

therefore, finished

to

size

on

the

inside of

the

cylinder bore when

the

bore

dia

meter

is

ground

to

size.

The

later

model

6A4-150-83

engines

have

two

lock pins positioned

90

degrees

apart

to

hold

the

cylinder liner

in

position.

The

model

6A4-165-B3

engine

has a step

machined

in

the

crankcase

at

the

cylinder

mount

bore. This

step

acts

as a stop

for

the

cylinder liner

and

only one liner lock pin

is

used

in

the

cylinder.

The cylinder bore

is

finish-honed

to a diameter

of

4.500"

to

4.501".

The

final finish

is

a fairly

coarse honing operation

to

insure

satisfactory

seat-

ing

of

the

piston rings

contacting

the

liner surface.

Tests

have proven

that

with

the

use of good lubri-

cants,

changed

regularly,

the

liners

will

show little

wear

over a tong period of operation.

Cylinders for

the

model

6A4-150-83

and

the

6A4-165-B3

are

mode from

the

same

costing.

Cylinders for

the

165 hp model have

different

valve guides from

the

1

SO

hp

model

and

an

addi-

tional shot peening

operation

has

been performed

on

th

e cylinder

base

to provide

added strength.

It is, therefore, mo

st important

that

a cylinder

originally

mahufactured

for

the

1

SO

hp

engine

MUST NOT be

token

from

stock

and

assembled

on a 165 hp engine.

All

cylinders for

the

model

6A4

-1

65-B3

engine

have

shot

peened bases.

During initial assembly,

the

aluminum

cylinder

ca

sting

is

heated

and

held for two hours

at a tem-

pe

rature

between 6250 and

650°F

to

anneal

the

casting a nd

prepare

it

for installation

of

the

liner,

valve se

at

inserts

and

valve guides, all

of

which

are

installed while

the

casting

is

in

the

heated

condition.

VALVE GUIDES

The

intake

and

exhaust

valve guides

are

a high-

quality

cast

iron

and

a re installed

as

previously

explained, when

the

cylinder

casting

is

heated.

(See Fig.

15-1,

2.) T

he

outside

diameter

of

the

valve guides

is

.5640"

to

.5645"

and

the

inside

diameter

of

the

reamed holes into which

they

are

pressed

is .5605"

to

.5610",

giving a

shrink

fit

of

.0

03"

to

.004". On

later

engines,

the

reamed

hole

is

.5615"

to

.562"

giving a

shrink

fit of .

002"

to

.003".

When

installed,

the

distance

down

from

the

mac

hined

top

surface

of

the

cylinder to

the

top

of the guide

is

.318"

to .354".

The

inside

diameter

of

both guides

is .375"

to

.376"

on

the

FIG.

14.

Cylinder Liner Lock Pin

and

Set

Screws

1. Cylinder

liner

3.

liner

Lock Pin

2.

Cylinder Hold-Down

4. Lock Pin Screws

Fl

ange

FIG. 1

S. Valve Guides

and

Top

Face

of

Cylinder

1.

Intake

Valve Guide

5.

Topped

Holes for Valve

Cover Screws

2.

Exhaust Va lve Guide

6.

Tapped

Holes for Rocker

3.

Intake

lifter

Tube

Hole

Support

Screws

4.

Exhaust

lifter

Tube

Hole

early model

6A4-150-B3

and

831 engines. On

the

loter

model

6A4-150-B3

engines,

the

diameter

of

the

exhaust

valve

stem

was increased, which re-

quired

an

increase

in

the

insi

de

diameter

of

the

exhaust

guide to

.4375"

to

.4385".

On

the

model

6A4-165-83

engine

, the Inside

diameter

of

both

5

21

2

valve guides

is .406

3"

to

.4073". The

valve guides

should be conc

entr

ic with

the

valve

seat

face

within

.002 total in

dic

ator

reading.

To replace

the

guides,

heat

the

cylinder

to

a

tem

perature

of

625°

to

650°F.

Support

the

cylin-

de rs on the he

ad

end, with supports close

to

the

gu ide to be pressed out. Press guide

out

from inside

th

e cylinder head. Me

asure

the

internal

diameter

of t

he

hole in

the

cylinder-standard

inside

dia-

meter of

ream

ed

guide holes on

both

the

intake

and exhaust

is .5605"

to

.5610"

and

install over-

size guides if necessary.

Intake

and

exhaust

valve

guides can be ob

tained

in

three

oversizes:

.001",

.00

2", and .005".

After

selecting

the

proper

size

guide, and with

the

cylinder

heated

to

625

° to

650°F. , install

the

new guide

by

coating

it with

white lead a nd pressing it into position until

the

top

of the guide

is

.318"

to

.354" below

the ma-

ch ined top surface

of

the

cylinder head.

Later engine models have inlet

and

exhaust

valve guides with a shoulder incorporated.

The

cylinders

that

take

the

shouldered

guide

have

an

additional

counter

bore in

the

bottom

of

the

valve

sp

ring well.

With

this

latter

type, it

is

only neces-

sar

y to press

the

guide into

the

cylinder until

the

shoulder

bottoms

on

the

counterbore

in

the

spring

well.

VALVE

SEAT INSERT (INLET)

2

FIG.

16.

Valve

Seat

Inserts

1. Inlet Valve

Seat

2.

Exhaust Valve

Seat

The inlet valve

seat

insert

in

the

aluminum

cylinder

head

is

made

of

iron alloy

to

give long

se rvice life. (See Fig. 16 -1.) It

is

installed when

th

e cylinder

is

heated

to

625

° to

650°F.

by being

pressed into

the

2.1255"

to

2.1265"

reamed

hole

in the cylinder head.

The

outside

diameter

of

the

inlet valve sea t insert

is

2.1295"

to

2.1305",

giving

a shrink fjt between

the

intake

valve

seat

insert

and

the reamed hole

of

.003"

to

.005".

When

the

insert

is

properly

seated

and

the

shrink

fit obtained,

the

seat

is

further

secured by rolling over

the

aluminum

material

of

the

cylinder surrounding

the

insert.

The

inlet valve

seat

is

then

ground to a

30°

angle

with a

seat

face

width

of

1/1

6".

Some

of

the

later

model

6A4-150-B3

and

B31

engines

and

the

early

6A4

-165-B3 engines have

alloy steel

seat

inserts with a

hard

stellite face.

On

the

6A4-165-B3,

the

diameter

of

the

reamed

hole

in

the

cylinder

has

been decreased to

2.1245"

to

2.1255".

This produces a shrink fit on

the

insert

of

.004"

to

.006".

VALVE SEAT INSERT (EXHAUST)

The

exhaust

valve

seat

insert

is

of

stainless

steel.

(See Fig. 16-2.) This

material

has

been

found

highly

resistant

to the corrosive action

and

high

temperature

of

the

hot

exhaust

gases,

thus

reduc-

ing wear

and

warpage.

The

exhaust

valve

seat

insert

is

installed

in

the

same

manner

as

the

inlet

valve

seat

insert

and

the

aluminum

cylinder

head

material rolled over it.

The

seat

insert

is

then

ground to a 45°

angle

with a face width

of

3/

32".

Some of

the

later

model

6A4-150-B3

engines

and

the

early model

6A4

-165-B3

engines

also have

alloy steel

seat

inserts with

the

hard

stellite face.

The

outside

diameter

of

the

exhaust

valve

seat

insert

is

1.6555"

to 1.6565".

The

inside

diameter

of

its

reamed

hole

in

the

top

of

the

cylinder

head

is

1.6514"

to

1.6524",

giving a

shrink

fit

of .0031"

to

.0051".

On

the

model

6A4-165-B3,

the

diameter

of

the

reamed hole

in

the

cylinder

head

is

1.6504"

to

1.6514",

The

outside

diameter

of

the

insert

is

1.6555"

to

1.6565".

This produces a shrink fit on

the

insert

of

.0041"

to

.0061".

The

seat

inserts may be replaced by

cutting

them

out

to a thin

shell with a boring tool.

The

stellite

faced inserts should rarely ever need

to

be replaced.

If

it

does become necessary to remove this type

of

seat

insert, a high-speed steel tool will

be

required

as

the

stellite face

is

very difficult to

cut

through.

Care

must

be

used when removing

the

shell,

not

to

damage

the

reamed hole

in

the

cylinder head.

Heat

the

cylinder

to

625

0

to

6500 for two hours

and

press

in

the

new inserts. It is

important

that

the

inserts

bottom

flush

in

the

reamed hole

and

that

they

are

held

in

position during

the

time

the

cylinder

is

cooling. If it should become necessary

to replace

the

valve

seat

inserts,

the

operation

must

be performed with

the

proper tools

and

care

must

be

token

to

hold

the

seat

face

widths to

the

specified dimensions, using narrowing

stones

or

cutters.

CYLINDER TAPPED

HOLES

AND STUDS

The

tapped

holes

in

the

cyl

inder for

the

rocker

block

and

inlet manifold screws

are

5/

16"-18

NC

thread

to a depth

of

5/ 8".

The

two

exhaust

stack

studs,

5/16"-18

NCstud

end, 5/

16"-24

NF-3

nut

end, 5/ S"

height

of

studs

installed.

Some cylinders have

three

studs

in

the

top cylin-

der

surface

for

fastening

down rocker assemblies.

The

studs

are

5/ 16" -18 NC

stud

end

and

5/16"-24

NF-3

nut

end.

The

stud

height

is 1-33

/ 54".

ROCKER

BLOCK

SCREWS

In

the

later

engines,

three

5/16"-18

x 1-3/

4"

hex

head

cap

screws

are

used to

fasten

rocker

assemblies

to

the

cylinder

instead

of

the

studs

mentioned above.

22

CYLINDER - O

IL SEAL

RING: (FIG. 17-6)

-6

2

3

4

FIG.

17.

Cylinder

1. Inlet Valve

Port

4.

Cylinder Fins

2.

Exhaust

Stack

Stud

S. Cylind

er

Hold-Down

3.

Ex

haust

Valve Port

Flange

6. Cyli

nder

Flange Oil Seal

Wh

en installing

the

cylinder on

the

crankcase,

inspect

the

cylinder pod

surfaces

on

the

crankcase

and

the

bottom

of

the

cylinder

flange

for nicks

and burrs.

See

that

these

surfaces

are

clean.

The

oil seal ring

is

installed

on

the

cylinder liner

and

pushed bock

so

that

it

is

snug

against

the

cylinder

flange a ll

around.

It

is

important

to

check

the

chamfer

on

the

crankcase

at

the

cylinder bore

to

deter

mine

the

proper

oil seal ring

to

use. I f

the

chamfer diameter

is

4-13/ 16", use

the

seal ring

called for in

the

Ports

Book for

engines

up

to No.

1

1020. I f

the

chamfer

diameter

is

4-29/32",

use

the sea l ring called for in

the

Ports

Book for

engines

No.

11

021

and

up. A new seal ring should

be

used

each time

the

cylinder

is

removed

and

reinstalled

and

must fit snugly into

the

chamfer

in

the

crank

-

cas

e to

prevent

oil leaks.

CYLINDER HOLD-DOWN NUTS

The cylin

der

is attached

to

the

crankcase

by

u

si

ng fo

ur

7/1 6" -20

and

four

3/8"

-24

hex

nuts

with special wa

shers

having

rounded

edges

and

safetied wi

th palnuts.

The

nuts

should all be pulled

down evenly

to ass

ure

a good seal

at

the

crankcase

cylinder pod.

CYLI DER FI

NS

Inasmuch

as the cylind e r cooling

depends

on

the

maximum

flow of a ir ov

er the

cylin

der

fins, it

is

imperative

that

the

ent

ire cylin

der

fin a rea be kept

clean

and

free from any

obstr

uctions. T

he

engine

cowling should

be

checked freq

uentl

y fo r

leaks

and

kept

securely tig

htened in

its cor

rect

position .

HELICOILS

Stainless

steel

helicoil s

park pl

ug inserts a re

used

to

accommodate

two spark plugs in

the

head

of

the

cylinder.

Their

use

greatly

improves

spark

plug

thread

wear and

maintenan

ce and, when

nec-

essary,

they

can

be

easily repl

aced.

(See Fig. 18.)

Fig.

18.

Helicoil

Replacement

1. Removing Helico

il

I s

ert

To remove

the

helicoil,

insert

the

extrac

ting tool,

# 13825, in

the

spark

plug hole.

(Fi

g. 18-1.) Top

I ightly with a

soft

hamme

r. Remove

insert

by t urn-

ing it

out

in

on

anti-clockwise

direction

.

2.

Reta pping

the Thre

ads

Retap

the

spark

plug hole (Fig. 18-2) to remove

any

small nicks

and

to

clean

the

threads,

us ing t

he

bottoming

finish

top

tool # 13822 to a

depth

of

3/

8

"

23

3.

nstall ing t

he

Helico U

Inse

rt

Pu

ll man

drel of

the inserting tool, # 13826, back

into the

sleeve and pl

ace the helicoil

spa

rk plug

inse

rt

in

the recess

of

the

sleeve, t

ang

end

of

the

in-

sert

toward

the

threaded

end of the sleeve. Adva nce

the mandre

l until its s

lotte

d end e

ngag

es

the tang

of

the

insert. Rota

te

mand

rel clockwise while hold-

ing

the

sleeve, until the l

ead

thread

of the insert

is

almost

flush, b

ut

not above

the

base

of the

s

le

eve. Hold

the

sleeve

of the insta ll

ing tool firmly

against

and

in line with t

he

spark

plug hole. Tu rn,

but

do

not

press down on

the

man

drel

and

screw

the insert

all

the way

into t

he spark

plug hole (Fig.

18-3) until

the end

of

the

top

thread

of

the inser

t

is

a h

alf

turn

inside the

top

thread

of

the spark

plug hole.

4.

Removing

the Helicoil

Tong

24

B

reak off

the

tang with a p

air

of

long nose pliers

(Fig. 18-4

).

I n

ser

t th e

expanding

tool, #

18295,

an

d torque to 1

20

in.-Ibs. (Fig.

18-5).

5. Torquing

the

Expander

With

the

exp

anding to

ol

sti

ll

in posi tion , pl

ace

the

staking

tool, # 1

829

6,

on the

fac

e of

the

spark

plug hole. Ta p

the

tool lightly w

ith

a s

oft ham

me r

(Fig. 18-6 ).

6.

Securing

the

Helico

il

in

Position

This ope ration knurls a lig ht

chamfer

arou

nd

the spar

k plug hole

and

seals

the insert

in

place

.

Remove

the staking tool

and

expand

er tool.

XVII-

VA

VES

AND VALVE SPRING

VA

LVE

S: (FIG. 19)

2

--

---

-

FIG.

19. Valv

••

1.

Intake

Valve 2 .

Exhaust

Valve

On model

6A4

-150-

83

and

B31

engines

the

alloy ste

el

inlet valve

has a stem

diameter

of

.3

71

7"

to .3725"

and a 30°

angle

seat.

The

seat,

when ground, must be

concentric

with

the

steam

with

in . 015" total indic

ator

reading.

The exhaust

valve h

as

a speci

al he

at

and

cor-

rosion -resistin g a

ll

oy steel h

ead

welded

to

the ste

m.

The va

lve st

em dia

meter is .434

2"

to

.435

0".

Some

en

gi

nes h

ave

exhau

st

valves wi

th a steam diameter

of .37 17" to .3725". It

is very imp

ortant that

the

proper steam

diamet

er

valve be used wh

en repl

ace-

ment

is made;

otherwi

se,

the

clearanc e between

valve s

tem an

d guide will be inc orre

ct

and

serious

da

mag

e will re

sult

. A

ll

exhaust

valves have a

45°

angle se

at.

The sea t, when grou nd,

must

be con-

cen

tr

ic

with

the

stem within .

01

5"

total

indicator

reading.

Bo

th intake a nd exha ust va lves on

the

model 6A4-1 65-B3 engine

have

a s

tem

diameter

of

.4038"

to .4030".

VA

LVE SP

RING : (FIG.

20)

I

6

FIG.

20. Valve S

pring

1. Spring

Tensio

n Adj

ust-

me nt Shims

2.

Bo

tto

m W

asher

3. Val e Spring

Damper

4. Valve Sprin g

5.

Top Wash

er

6.

Valve Spring Re

tainer

Lock

The

valve spring

assembly

consi

sts

of

a single

co

il

spring, cupped

bottom

washe

r,

shoul~ere

d

up-

per was

her

a sp ring

dam

per

and

a spilt key or

ke

eper

to ho

ld

the

upper was

her

in position. The

two was hers serve to c

enter

the sp ring a bout

the

valve

ste

m.

The

valve spring must be asse mbled

in the cyli n

der with the spr

ing

damper

do

w~

to

void dam

age

to the

damper

and

other

valve Itnk-

age parts.

On

th

e model 6A4-1 50-B 3 and 831

engine

s, t

he
valve sp ring fo rce, when compressed to the indi­c

ated lengt

hs, is as follows: Spring compressed to

1 -5/ 8"

= 46

to

52 Ibs. and

at

1 -1/ 4" = 1 08 to

116 Ibs. These m

easu

rements a re made with the

sp

ri

ng da mper removed. Wi th the valve and va lve

springs

asse

mbled in

the

cylinder,

the

valve should

suppor

t a weight of

SO

to

60 Ibs: before t.he valve

s

tarts

to leave its

seat

in t

he cyll der.

Adju

stm

ent

for assembled we

ight

is

accompli shed by

adding

or

removing shims UNDER

the bottom

washer. The

shims

are available

in

.016" and

.031"

thickne

ss.

Valve

trav

el

from the closed

to

the

fu

ll

open posi-

tion must be a

MI

NIMUM

of

.39

0"

to insure proper

operation. With t

he

va lve

in

its full open positi.on

on

the

engine, the spri ng coi I shou ld

not

be solid;

otherwise serio us

trouble

with rocker

arms

and

I

ifter

rod~

m

ay

be experienced.

YVhe

never seryice

operati

ons

are

performed

affecttng

valve springs

or component

parts, always

che

ck

the spri

ngs for

a minimum travel

of .390"

and

check

for clea

rance

between the

spring coils when

the

valve

is

in

the

full open position.

On

the

model 6A4-165-B3 engine, the force

exerted

by

the

valve spring wh

en

it

is

compressed

to

1.343" without the dam

pe r installed should

be

138 to 1

46

Ibs. W it h

the

valves

and

spring

asse

m-

bled

in

the

cylinder,

the

valve should

supp

ort a

weight of

68

to

75

Ibs. befo re the valve leaves its

sea t. The valve

and

springs a re so designed on

the

165 hp engine

that

NO SH I

MS

ARE EVER RE-

QU

IRED UNDER THE BOTTO M WASHE

OF THE

VALVE SPRINGS. The actual

opera

ting valve travel

in

the

mod

el 6A4

-165-B3

engine

is .500". The

mov

ement obtainable

by depressing the valve until

th

e spring

is sol

id is co n

siderab

ly

over .

500",

how-

ever.

25

XVIII

- VALVE ACTUATING MECHANISM

1

---

2 -

-"""11

FIG.

21.

Valve

Train

1. Va lve Rocker

Arm

4.

lifter

Rod

2.

Va lve

5. Hydraulic

Lifter

3. Rocker

Arm Support

'---4

5-~

The

valves

are

actuat

ed from

the

cams

haft

thro

ugh

hydra

ulic valve lifters,

lifter

rods,

and

val ve roc

ker

assemblie

s, which

contact

directly

on

t

he

valve stems. (See Fig.

21

.)

L

ubrication

to

the rockers

and

valves is

accom-

plished witho

ut

use

of external

oil lines

since

the

oil flows

through

drilled

passages

in

the

lifters/

lift

er

rod s,

adjusting

screws,

and

rockers

to

insure

sati

sfa

ctory lubrication

to

these

parts

and

the

va lves

themse

lves.

Ca

ution

must

be

taken

when

replacing

lifter

units,

li

fter

rods, a

nd

adjusting

screws

to

make

su re that they

are

of

the

prop

er

type

. Both a forged

type a nd a st

amped

type

of

valve rocker

are

used

in

the

model 6A4-1

50

-83

and

6A4-165 -

B3

engines.

The

adjus

ting screw in

the

forged

rocker

has

a

5/ 1

6"

-

24

thread,

and

the

adjusfing

screw in

the

st

amp

ed rock e r

has

a 3/

8"-24

thread.

Where

a

di

fference exis

ts from

one

engine

to

another

in

pa r

ts

ha ving the

same

function,

the

Parts

Book

shows the correct

part

number

for specific

engine

numbers.

HYDRAULIC

LI

FTERS

(J

- l

FI

G.

22. Johnson Hydraulic Valve Lifter

1. R

etainer

Ring

4.

Valve

Cage

2.

Pist

on

S. Lifter Body

3.

Retu rn Spring

The

hydraulic lift

ers h

ave proven

to

be

dependa-

ble

through years

of

usage. The

ill

ustrated

views in

Figure

22

shows the simplicity

of

construction,

togethe

r w

ith

the

few pa

rts that

comprise

the

as-

sembly

of

the Johnson

Products lifter,

and

Figure

23

sho

ws

the

Wilcox-Rich

li

fte

r.

:---3

FIG. 2

3.

Wilcox- Rich Hydr

aulic

Valve Lifter

1.

Plunger

Assembly

2. Cylin

der

Assembly

3.

Lifter Body

Oil

under pressure from t

he

engine

lubrication

system

enters

the

lif

ter

body

chamber

through

two

inlets

in t

he

annu

lus

aro

und

the

body. This

annulus

indexes with a hole drilled in

the

lifter

guide

hole

in

the

crankcase. The Iifte

r body

chamber

is

thus

filled with o

il

under

pressur

e. A

spring-loaded

valve, loc

ated

und

er

the r

eturn

spring, lifts

off its

seat due

to

the

pressure of the oil in

the

lifter

body

chamber and

allows oil

to fill the lift

er

piston

chambe

r.

Wh

en the

valve

is

closed, the oil in

the

piston

chamber, being

non-compressib1e,

completes

a lift

ing

mec

hanism that

opera

tes

against

the

lifter

rod

as

positively

as

though

the

entire

lifter

unit w

ere

a single solid piece. As

the

valve train

expands

and cont

rac

ts with

changes

in

engine

temperatu

re, the lif

ter

adjusts

its own

length

to

c

ompe

nsa

te

for

the changes.

IAcclJrately

deter-

mined

cle

aran

ce to within one

ten-thousandths

of

an

inc h

bet

ween

the piston

and

the

bore

of the

lif

ter

body

permits

the esc

ape

or

leakdown,

as

it

26

is

commonly

called,

of

a small

amount

of

oil from

the

chamber.

This

leakage

automatically

com-

pensates

for

any

expansion

in

the

valve

train,

allowing positive valve

seating. When

the

valve

frain

contracts,

the

piston

return

spring holds

the

piston

outward.

This relieves

pressure

on

the

oil in

the

piston

chamber

and

an

the

valve

under

the

return

spring.

The

valve moves from its

seat

and

permits

the

intake

of

oil from

the

engine

lubrica-

tion

system

through

the

lifter

body.

Thus,

the

lifter

unit

corrects

its

length

each

time

the

valve

closes,

to

maintain

zero

clearance.

Some

engine

models

have a slightly

reworked

lifter

installed.

A

second

annulus

has

been

added

to

the

body

to

allow more oil

to

the

rocker

arm

mechanisms.

However,

this

change

in no way

affects

the

operat-

ing principles

of

the

lifter

valve

described

herein.

Valve

lifters

furnished

by

both

Wilcox-Rich

and

Johnson

Products

are

used

in

model

6A4-1S0-83

and

B31

engines.

These

lifters

are

completely

in-

terchangeable

and

both

have

a body

diameter

of

.8745"

to .8740".

The

lifter

body

clearance

in

the

guide

is

.001"

to .

002". The

Wilcox-Rich

lifter

is

easily

distinguished

from

the

Johnson

Products

lifter

by

the

plunger

spring which

is

visible in

the

open

end

of

the

Wilcox-Rich assembly.

The

valve

lifter

for

the

model

6A4-165-83

engine

is

manufactured

by

Johnson

Products

and

has

a body

diameter

of .9360-.9355".

Care

must

be

taken

when

replacing Iifters

in

the

165

hp

model

to

see

that

the

smaller

diameter

lifter

for

the

150

hp

model

is

not

used.

The

large

diameter

I

ifter

assembly

is

easi

Iy

recognizable

by

the

Jorge

chamfer

on

the

lifter

rod

end

of

the

body.

CAUTION:

Hydraulic valve lifters for

the

older

model four

and

six-cylinder

Franklin

engines

with

the

external

rocker oiling

system

must

not

be

used

in

the

6A4-150-B3

and

831

engines.

These

old

style

lifters will

fit

the

guide

hole

in

the

crankcase,

but

they

are

nQt

machined

to

provide

an

oil

passage

to

the

hollow

lifter

rods for

rocker

and

valve lubri-

cation.

HYDRAULIC LIFTER (SERVICING)

To

disassemble

the

Johnson

type

hydraulic

lifter,

remove

the

retainer

ring from

the

top

of

the

lifter

body. (See Fig. 22-1.) This

is

done

by prying

one

end

out

with a small

knife

blade

or

similar

tool.

I f

the ,tappet

is

full

of

oil

and

the

piston

is

tight

against

the

ring, first press

the

piston down

slightly

by

pushing

against

the

upper

socket, forcing some

of

the

oil

out

past

the

piston.

When

the

retainer

ring

is

removed,

the

action

of

the

return

spring

pushes

the

lifter

piston

out

of

the

lifter

body.

In

this

position,

the

piston

return

spring

and

valve

cage

may

be

easily removed.

With

the Iifter

parts

separated,

give

them a thorough

cleaning.

During

the

cleaning

process,

do

not

enlarge

the

holes

or

change

the

dimensions

of

the

piston

or

the

bore

of

the Iifter

body by using

any

tool

or

material

with

an

abrasive

action.

Clean

each

unit

separately

to

avoid mixing

parts.

This

is

important

as

it would

change

the

leak

-down

rate

and

affect

the

proper

operation

of

the

unit.

After

the

lifter

parts

are

cleaned

and

dried, a simple

check

can

be

mode

to

test

the

action

of

the

lifter

valve

assembly

and

the

leak-down

rate,

which

is

controlled

by

the

clear-

ance

between

the

piston

and

the

lifter

body.

Install

the

valve

assembly

and

piston without

the

return

spring,

in

the

lifter

body. Place

the

unit

on a

bench

and

tap

the

piston

head

sharply with

the

forefinger. If

the

unit

is

in good

condition,

the

piston will

rebound

sharply,

due

to

the cushion

effect

of

the

air

in

the

lifter body

chamber.

If

the

pi'ston does

not

react

in

this

manner,

it

would indi-

cate

improper

seating

of

the

valve

or

excess ive

clearance

between

the

piston

and

lifte r body.

WHEN

REASSEMBLING THE UNIT, IT

IS

VER

Y
IMPORTANT TO REPLACE THE SAME PARTS
REMOVED FROM

THAT

PARTICULAR

UNIT

AS

THEY ARE A MATCHED ASSEMBLY.

When

installing

the

hydraulic

lifters, no oil

should

be

used

in

the

chamber.

When

the

lifters

are

installed

dry,

the

two small holes

extending

through

the

piston

skirt

vent

the

air

very quickly,

and

oil from

the

engine

lubricating

system

operate

s

the

lifters.

The

outside

of

the

lifter

body

should

receive a

light

coat

of

oil, however,

before

being

installed

in

the

crankcase.

Very

infrequent

servicing

is

required

and

it is

advisable

not

to

disturb

the

lifters unless

there

is

a

direct

cause

traceable

to

lifter

performance.

Always

replace

the

lifters in

their

original

locations

on

the

engine.

Some

engine

models

utilize

a Wilcox-Rich

hydraulic

lifter

rather

than

the

Johnson

Products

unit

just

described.

The

Wilcox-Rich employs a

ball

check

valve

arrangement

to control

the

oil

flow. However,

the

operating

prinCiples

of

the

two

lifters

are

practically

the

same

.

The

disassembly

of

the

Wilcox-Rich lifter

is

ac-

complished by first lifting

the

hydrauliC

unit

out

of

the

lifter

body.

It

shou

Id

lift

out

easi

Iy,

but

if

an

excessive

deposit

of

sludge

or

dirt

prevents

it

from doing so,

immerse

the

lifter in

clean

solve

nt

and

wash

it

until

clean.

The

plunger

or

piston is

locked

to

the

cylinder

by

the

plunger

spring whi ch

fits

into a counterbore

in

the

cylinder.

To

remove

the

plunger

from

the

cylinder,

first

unlock the

spring.

This

is

done

by

simply

turning

the

plunger

and

spring in

the

direction

that

would

"wind

Up"

the

spring. Pull

outward

at

the

same

time,

and

the

plunger

should

then

come

out

easily. If

the

plunger

should

be

stuck,

it

wi

II

be

caused

by

one

of

two

things

:

1.

A

carbon

deposit

which

has

formed

at

the

shoulder

of

the

cylinder

above

fhe

plunger.

2.

The

oil

chamber

is

still filled with oil,

seale

d in

by

the

ball

check

valve, holding

the

plunger

against

the

carbon

ring.

To

determine

whether

or

not

the

plunger

is

stuck,

insert

a wooden

stick

in

the

oil

inlet

hole

at

the

bottom

of

the

cylinder.

This

will

unseat

the

ball

check

valve

and

allow

the

oil to

drain

out. If

the

plunger

still

remains

stuck

after

this

procedure,

soak

the

unit

in

solvent

and

use

taped

pliers if necessary. A

combination

twisting

and

pulling

motion

will

separate

the

plunger

from

the

cyl inder.

AS

IN THE CASE OF THE

JOHNSON

UNIT,

THE PLUNGER

AND

CYLI NDER

ARE

SELEC

-

TIVELY FITTED

AT

THE FACTORY,

AND THE

PLUNGER FROM ONE CYLINDER

CANNOT

BE

USED

IN OTHER CYLINDERS.

After

cleaning

and

reassembling

the

unit,

the

method

of

checking

by

creating

an

air

pocket

in
the

cylinder

and

quickly

releasing

the

plunger

to

see

if it kicks

back

up is

the

some

as

previously

described

for

the

Johnson

lifter.

27

LIFTER

ROD

AND

TUBE

. The rockers

are eith

er

metal

stam

pings or forg-

The

lifter rod

is

of

seamless

steel tubing. It

has

a ball

end

which

contacts

the

cup in

the lifter

plunger. A

cup

on the top

of

the lift

er rod c

ontacts

the

ball

end

of the dri lied valve rocker a

dju

sti ng

screw. (See Fig .

24-1.)

I f either ti ps on the lifter

rod show

appreciable

wear,

the lift

er rod assembly

should be replaced .

The

holes

in

the t ips a

nd the

hollow rod

must

be free

of

foreign

matter,

as

oi

I

from

the

engine

must

pass

thro

ugh the lift

er

rod

ass

embly

to

lubricate

the

rocker arms

and

valve

assemblies.

3

FIG. 24. Lifte

r Rod, Tube

and

Oil Seals

1. Lifte

r Rod Assembly 3. Lif

ter

Rod T

ube

2.

Lifter

Rod Tube

Pa

ckin

gs

The

lifter rod should

be

straight

within .

005"

total

indicator read

ing.

The lift

er

rod

is encas

ed

in a

lifter

rod

tube

which contains a coiled spring

type

circlet

fitted

in

the recess of the

bead

on

the

crank case

end

of

the

tube. (See Fig. 24-2.)

This

circlet

centers

the

lower end

of

the

push rod on t

he lifter

cup

and

serves

as a guide

to

position the rod during ins

talla-

tion and engi ne ope

rat

ion. Early en

gines had the

Wilcox-Rich valve

lifters

and

were not insta lled

with cir

cl

ets

in

the

lifter rod tubes. W

hen any

of

the lifte

r rod tubes

are

removed,

the

cran

kcase

end should be examined at the bead to det

erm

ine

if it c

ontains

a ci

rclet

. A spring circlet

shou

ld

be

insta lled before

the

tube

is reassembled

on

the

engine. This

is p

articularly

imp

ortant

if

the

John

-

s

on

Pro

ducts

hydr

aulic

lifter

is

being used.

NOTE: I t

is

very

important

to ma

ke sure that

the

ball

end

of the lifter rod

is posi

tioned in

the

c

up

in the va lve lifter. F

ailure

to

do

so w

ill cau

se

impr

oper

engin

e ope

ration

and

damage

to

the

valve

op

eratin

g parts .

ROC

KE

R PINS

AND

ROCKE

RS

T

he ste

el rock r pins a re mo

unt

ed through three

support blocks

on the

head

of

the

cylind e

r. (See

Fig. 25.)

I f

the

valve rocker s a nd suppo

rts

hav

e b

een

~e":l0ved

,

it

i.s

important

to

see

that

a welch plug

IS In

stalled

In

the

bore

of each

roc

ker

pin

just

inboa rd of the supp

ort

screw hole.

The

absen

ce

of

this

J?l

ug w

ill

elimi na

te

the

safe

ty

feature

of haVi

ng

an

ad cross feed

between

the two rocke

rs

in

case

the

oi

I passage

to one roc k

er

gets plugged. The

oil

h

ol

e in the roc ker pin should face down toward

the

cylind

er

head for

the

same reason .

.

The

rockers (See Fig. 25-2, 3) m

ay

be id

enti

-

fi

ed by the

part

number which is stamp

ed

on

each

piece. Some roc

kers

hav

e only the la

st

number of

~h

e

pa rt numb

er

sta mped on

the

piece,

thus,

the

In

let roc k

er

is

stamped

with a

"7"

and the

exhaust

ro

cker

is stamped with

an

1/8",

mgs,

depending on

engine seria l number.

All of

the

forged type rockers, both in ta ke a nd

exhaust, have

a drilled o

il

hole th

at opens

out the

valve

end

of the rocker a r

m. There are so

me

stampe

d type

intake

valve ro

ckers that are dril led

so

that

the oil

hole opened dire

ctly

on the valve

s

tem

tip . Some

of

the

stam

ped type

exhaust

valve

rockers were drilled so

th

at o

il

holes open

ed both

at the end

of the rocker arm

and

also direct

ly

on

the

valve

stem

ti p. All

of the

inta

ke va lve rockers

are

interchangeab

le with

each

other. All

type

s of

e

xhaust

roc

ker are also

int

erchangeable with each

other.

Any

of

the

rockers

mention

ed above m

ay

be

used on all model

6A4-150-B3

and

B31 engines.

It

is

important that

only the forg

ed

type rock e r

be

used

on

the

mod

el

6A4-165-B3

engine.

Soli9

aluminum

blocks were used as rocker

sup

-

ports

In

the

early engines. A metar

stam

ping is

used

as

support

blocks for

the

rock

ers

in the late

r

engines. (See Fig.

25-5. ) These

are

attach

ed to

the

cylinder

head

by

means

of

5/

16"-18

x 1

-3/

4"

hex

head

cap

screws

and

are

secured

by

a ta b-

typ.e lockwasher. Some

engines

having

studs in the

cylinder

head

use plain washers, 5/ 16"-24 plain

nut,

and

5/ 16"-

24

palnut

to

secu re.

alu

minum

block

supports

to

the

cylinder.

Other

engines use

aluminum

blocks

secur

ed by 5/ 16"

-18

1-3/ 4"

cap

screws with 5/

16"

shakeproof

washer

s. The

stamped

steel

and

the

machined

aluminum

block

rocker

supports

are

interchangeabl

e on t

he

6A4 -

1

50-83

and

831

engines

only. Either type support

may

be used with e i

ther

the stud

or

cap

screw hold-

do

wn

fas

tening

s.

The

roc

ker

support

for

the

mod

el

6A4~

16

5-83

engine is

of the s

tamp

ed typ e. It is

n

ot mte

rchangeabl

e with t

he

rock

er

supports for

t~e

other

mode l

engin

es as it

support

s t

he

rocker

pm at a

great

er hei

ght

above t

he top of the cyl in-

de.r. A 3/

8"-24

hex ja m n

ut

on a 3/ 8"-2

4 NF-3

dnlled rocke

r adjust ing screw is used on the

stamped

rocker. A 5/ 16"-24 j

am nut and ad

justing

screw

are

used

on

the

for

ged

rock e

r.

FIG. 2

5.

Valve Rockers and Supports

1. Roc

ke

r Assembly Hold -

4.

Rocker

Pin

D

ow

n Screw and Lock

5. R

ocker Suppo

rt

W

ash

er

6. Roc k

er

Arm Ad j

ust

ing

2.

Ex

ha ust Valve Ro

cker

S

cre

w

Ar

m

7. Rocker Arm Ad ju

sting

3. In ta

ke

Valve Rocker

Screw N

ut

Ar

m

28

5

Due

to

the

increased

height

of

the

rocker

sup-

ports on

the

model

6A4

-165-B3

engine,

dimpled

rocker covers

are

used.

CAUTION:

A model

6A4-

150-

B3

rocker cover should

not

be used on

the

165

hp

model

as

damage

to

the

cover

and

possibly

the

rocker will

result. The

dimpled

cover

may

be

used for

replacement

on all models. Refer

to

the

Parts

Book for t

he

correct

part number

and

refer-

ence.

The

rocker

arm

bushing

inside

diameter

is

.625"

to

.

626

ft

The

rocker pin o

utside

diameter

is

.6225"

•

to

.623",

giving a

bushing

on

pin

clearance

of

.002"

to

.0035".

The

side

clearance

between

the

rocker

arm

and

supp

ort

is

.003"

to

.008"

('006"

desired) .

The

rocker pin fit in

the

aluminum

blocks

is

.001"

tight

to

.0005"

loose.

The

rocker pin

fit

in

the

stamped

supports

is

.001"

tight

to

.0015"

loose .

XIX

- LUBRICATING SYSTEM

Being Q

wet

sump

type

engine,

the

oil

pan

or

sump

(See Fig.

27)

is

attached

to

the

bottom

of

the

crankcase

and

has a maximum

service

capac-

ity

of

eight

quarts.

The

total

oil

capacity

of

the

6A4-165-B3

engine

is 8 3/4

quarts.

The

oil

is

picked

up

from

the

reservoir by

the

oil pump,

through

the

Floto

unit,

which

is

designed

to

receive oil from

the

cleanest

location within

the

reservoir. This

unit

incorporates

a wire mesh

filter

to

prevent

foreign

materials

from

entering

the

system. Some

of

the

early

production

6A4-150-B31

engines

were

not

equipped

with

the

Floto unit. On

those

units

a fine

mesh

screen

is

incorporated

in

the

end

of

the

oil

inlet

pipe assembly.

The

gear

type oil

pump,

driven by Q

gear

on

the

camshaft

gnd

mounted

inside

the

engine

to

the

left

crankcase

section,

delivers oil

under

pressure

to

the

oil by-pass

plate.

(See Fig.

28.)

This

plate

is

located

on

the

outside

of

the

crankcase

at

the

left

front

of

the

engine

crankcase

adjacent

to

#5

cylinder. Excessive oil

pressure

in

the

lubricating

system

of

the

engine

is

controlled by a spring

loaded

plunger

in

the

oil by-pass

plate.

The

plunger

and

spring

can

be

removed for inspection by

un-

screwing

the

rear

hexagon

nut

on

the

housing. On

some

early

production

engines,

the

by-pass

plunger

and

spring were

incorporated

in

the

oil

pump

cover

mounted

at

the

bottom

of

the

oil

pump

inside

of

the

oil

pan.

T

he

oil by-

pass

plate

also

contains

the

oil cooler

relief valve, (See Fig.

29),

which consists

of

a steel

boll, spring

and

boll

cage.

The

purpose

of

this

valve

is

to by-

pass

the

engine

lubricating

oil directly into

the

engine

lubricating

system

in

the

event

that

the

oil cooler

or

the

cooler oil

li

nes should

become

obstructed. The

oil cooler relief valve

can

be

re-

moved for inspection by unscrewing

the

hexagon

nut

on

the

front

end

of

the

by-

pass

plate,

just

abov

e the

oi

I cooler

return

I ine fitting.

On some early model

engines

equipped

with oil

by-

pass plu

nger

and

spring in

the

oil p

ump

cove r,

the

oil cooler relief valve

is

incorporated

on

the

oil cooler itself.

Oil

under

pressure from

the

pump

is

carried

by

an

external

oil line

to

the

oil cooler.

After

passing

through

the

cooler,

the

oi I is

returned

by

an

ex-

ternal

line

to

the

by-

pass

plat

e. It

is

then

directed

through

two drilled

passages

running

the

full

le

ngth

of

the

left

crankca

se half.

The

low

er gallery furnishes oil

to

the

left

bonk

of

hydraulic lifter

s.

The

upper

gallery furnish es oil

to

the

main, rod and camsha

ft

bearings . A drilled

passage

from t

he

first mentioned gallery

through

one

of

the

camshaft bearing bosses supplies oil to

the

right

bank

of hydraulic valve li

fter

s. Oil

is

directed from

the

hydrauli

c va lve lifters through

the

hollow lift

er

rods

to

oil

the rocker

arm

s, valves

and valve spr

in

gs.

The

connecti

ng rods are pro-

vided with

spray

holes

to

kee

p t

he cyli

nder

walls

and

piston pins in a heavy oil

spray

at all

time

s.

Timing

and accessory drive ge

ars

are

continu

ous

ly

bathed

in

oil. .

LUBRICATION SYSTEM - I

NSPECTION

AND

SERVI

CI

NG

Determine

the quanti

ty

and g

enera

l condi tion

of

the oil in the engin e

sump

by insp

ect

ing the oil

level

as

indic

ate

d on the

gra

duated

oil level g

auge

or dip stick.

This

.inspection should be mod e

at

least

daily,

or

more

often

if

opera

ting conditions

warrant.

Oil

of

the

som

e ty pe and viscosity may

be

added

to

bring

the

quantit

y to or n

ear

the full

mark.

Do

not

attempt

to

ope

rate

the

engine with

on

insufficient

quantity

of

oil in

the

sump

. Figure

26

shows

the

oil level

gouge

for the

6A4-150-B3

engine. The

gouge

or dip

stick

for

the

6A4-165-B3

is

similar

to

the

one sho

wn exc

ept

the

graduations

are

marked "3",

" 5" , "7"

and

"full"

.

FIG.

26.

Oil Measuring Stick

The

oil filler

cap

is

located

on

the

top

of

the

crankcase

cover on t

he

right

side,

near the re

ar

of

the

engine.

When

the filler

cap

is

removed, inspe ct

the gas

ket

for condition. Replace if worn.

Do

not

neglect

to reinstall

the

filler cap.

As previous

ly

explained, the

maximum

service

capacity

of

the

oil sump

is

eigh

t q

uart

s for the

150

HP

engine and

8-3

/ 4 quart

s for

the

165 HP

engine

. No useful purpose can

be

ser

ved by exceed-

ing this

maximum

quanti ty.

The

period for c

hangi

ng the

oi I wiJ

I va

ry

wit h

operating

conditions, howe ve

r,

the

maximum time

between

oil

changes

should

not

excee

d 25 hours.

Always

drain

the

oil whi le the

eng

ine is wa rm.

To

drain

the

oil, remov e the

sump

drain plug,

located

at

the

bo t

tom

of

the

sump

pa n

at

the right

rear

of

the engin

e. Reinstall the s

ump

plug and

secure

with

safety

wire to

the

tab

provided.

Refill

the

sump

with a good gra

de

of oil of the

recommended viscosity. Use only clean

containers

and

funnels . Ins

pect

the fill

er cap g

ask

et

and

rein-

stall

immed

iat

ely

to eliminat

e the possibility of

any

sma

ll

objects

be ing accidentally dr

opped into

the cran

kcase. Che

ck

the

leve l of

the

fresh oil in

the sump

by inspectin g

the

dip stic

k.

Screw

the

dip

stick

back

firmly into

place

. Remove any excess

oil

that

may have been

spilled on the engi

ne.

When

starting

an engi

ne, al ways rememb er to

observe

th

e o

il

pressure g

auge

. If the oil pressure

go

uge

does no t

start

to indica te within

2D

seconds,
and tapping the gouge gloss with the fingers does
not

have

an

immedi a

te

effect

, STOP THE ENGINE

AT ONCE

an

d investigate

the

couse.

29

The

maximum

oil

temperature

should

not

ex-

ceed

230°F.

The

oH

pressure during normal

opera

-

tion should be between

30

PSI

minimum

and

50

PSI

maximum,

with a minimum oil pressure

of

10

PSI

in

the

idle range.

When

starting

a cold engine, do

not

exceed

1200

RPM

engine

speed for

at

least

five

minutes

to

perrnit oil

to

thin

out

before going to

higher

RPM.

OIL PAN

2

riG. 27. Oil

Pan

Assembly

1. Oil

Pan

4.

Attachment

Screw

and

2.

Oil

Pan

Gasket

Shakepraof

Wosher

3.

Reinforcement

Band

5. Oil Drain Plug

The

oil

pan

is

attached

to

the

bottom

of

the

crankcase

and

serves

as

a reservoir for

the

engine

lubrication oil. (See Fig.

27,)

The

3/4"-24

square

head

oil

drain

plug

has a standard

pipe

thread

and

is

safetied

to a tab

by steel lacing wire.

A composition

gasket

is

installed

between

the

oil

pan

and

the

bottom

crankcase

surface. A solid

aluminum

reinforcing

plate

under

the

oil

pan

flange

of

stamped

pons

assures

desirable

oil

seal-

ing

qualities

at

this

porting

line.

The

oil

pan

is

attached

to

the

crankcase

by

twenty-four

5/16"-18 x 3/4"

fillister

head

screws

using 5/

16"

shakeproof

washers.

Three

plain

5/

16"-24

hex

nuts

with

5/16"

shakeproof

washers

are

used to

attach

the

rear

end

of

the

oil

pan

to

the

timing

gear

case.

To insure a proper

fit

and

prevent

oil leaks,

the

timing

gear

case

gasket

is

trimmed

flush with

the

crankcase

bottom

surface

and

the

trim

joints

coated

lightly with

sealing

compound.

Some

engine

models have a

magnesium

cast

oil

pan,

which

is

attached

to

the

engine

in a

similar

manner

to

the

stamoed

pan.

However,

the

cast

pan

has

sufficient

flange

thickness

to

eliminate

the reinforcement

band

necessary on

the

stamped

pan.

unitt

is

mounted

to

the

bottom

front

section

of

the

left

crankcase

half

by four

1/4-20

x 2-3/

4"

hex

head

cap

screws

and

four

1/4"

plain

washers.

The

cap

screws

are

safetied

with lacing wire,

or

in

the

later

engines with

tab

lock washers.

On

the

model

6A4-165-B3

engine, only

three

1/ 4"-20 x 2-3/4"

cap

screws

are

used with a

fourth

1

/4"-20

screw which is only 2-1 /

2"

long.

When

the

oi I pump

is

removed from

the

case,

the

location

of

the

various screws should be noted. It

is

essential

that

the

screws

be

reassembled in

the

same

loca -

tions from which

they

were removed.

The

threaded

hole for

the

cap

screw on

the

crankcase

pad, where

the

oil

pump

is

attached,

and

which

is

nearest

the

second

cam

lobe, should be

checked

carefully

after

the

screws

are

assembled. The

com lobe

in

its

closest position

must

clear

the

end

of

the

screw.

The

engine

should be

turned

over slowly by

hand

to

check

this

clearance

The

oil

pump

cover assembly, which includes

the

oil inlet pipe

and

oil inlet

float

stop,

is

sup-

ported

at

the

Floto

end

by a

bracket,

which

is

at-

tached

to

the

bottom

of

the

crankcase

by two

1/ 41f-20 x

5/8"

fillister

head

screws

(and

two 1/

4"

plain

washers). A clamp

is

used

to

fasten

the

oil

inlet pipe

tube

to

the

bracket

(Screws

are

safetied

with lacing wire.)

The

backlash

between

the

oil pump

gears

is

.004"

to

.008"

. Also,

the

backlash

between

the

drive

gear

on

the

camshaft

and

the

driven

gear

on

the

all

pump

shaft

is .004"

to

.008".

NOTE:

The

gear

on

the

oil

pump

shaft,

which

is

driven by

the

gear

on

the

camshaft,

has

been

made

of

cast

iron for some

engines

and

of

soft

steel for

other

engines. Also

the

camshaft

incor-

porating

the

oi I pump

drive

gear

is

made

of

cast

iron for some

engines

and

of forged steel for

other

engines. If

either

of

the

above

ports

are

replaced,

DO

NOT

assemble

a steel oil

pump

shaft

gear

ta

run with a

cast

iron

camshaft

gear. Any

other

combination

of

gear

and

camshaft

is

permissible.

The

cast

iron oil

pump

shoft

gear

can

run with

either

type

camshaft

. This

is

the

only

gear

that

will be supplied for service

replacement.

Order by

part

number

as

listed

in

the

Ports

Book

for this model. Gears for

earlier

models

are

dimen-

sionally

the

same

and

should

not

be used.

OIL INLET FLOAT (FLOTO)

OIL

PUMP

FIG.

28.

Oil

Pump

and

Floto

The

oi I pump

is a gear

type, positive displace-

1. Oil

Pump

Body

and

3. O

il

Inl

et

Pipe

ment

pump. (See Fig.

28.)

The

pump

drive

gear

Gears

4. Fl

ata

Stops

is

driven by a

gear

on

the

camshaft.

The

pump

2. Oil

Pump

Cover and

5.

Fl

oto

Clip

body, to which

is

attached

the

inlet pipe

and

Floto

Attachment

Screws

6. Floto

Unit

30

The Floto unit

(Fi

g.

28-

6),

is

composed of a

large di

ameter oil

screen, which

is

so

constructed

that

it floats

in the cle

an

upper

portion

of

the

oil

in the

pan

. T

he

screen prevents

any

foreign

matter

that

might

be suspended in

the

oil from entering

the o

il

inlet pipe.

The

Floto

unit

is

attach

ed

to

the oil

inlet pipe

by a

1/8"

x 1"

cotte

r pin

and

special wire clip.

The clip

is omitt

ed in

the

6A4

-16S-B3 engines.

When assem

bled,

the

Floto

unit

should

be

free

to move within

the li

mits

of

the

stops on

the

inlet

pipe.

The

posi tio n of

the

unit

when fu

lly

lowered

tow

ard

the

bottom

of

the

pan

should

be

4"

from

th

e bottom face

of

the

cra

nkcase

to

the

centerline

of

the

Floto

at

the

big

diameter.

I f

at

any

time the Floto

unit

is

removed from

the

oil inlet pipe

or

is in

any

way

damaged,

it

shou

ld

be

care

fully

check

ed for condition of inlet

pipe

an

d Flo

to

operation

bef

ore reassembly.

The

Flo

to shou

ld flo

at

if placed

in

oil or water. If it

sinks, it sh ould

be

rep laced.

Oil

BY-PASS PLATE

--12

F

IG. 29.

Oil

By.Pass

Plate

ond Relief Valve Assembly

1. Oil Pressure Relie f

Valve

7.

Oil Cooler Relief

Valve

Nut

Boll

Cage

2. O

il

Pressure Relief

Valve

8. Oil Cooler Relief

Valve

Gask

et

Spring

3. Oil Press

ure

Reli

ef Val

ve

9. Oil Coole r Relief

Valve

Spring

Gasket

4. Oil Pres

su

re Re lief Valve

10. Oil Cooler Relief

Valve

Pl

unger

Nut

5.

O

il

By-Pas

s P

late

11.

OiIOut-of-Engine
Fitting

Ball

12.

Oil

Into-Engine

Fitting

6. Oil Cooler Relief Valve

On all

but

a few

of the first engines of this

model,

the oil

by-pass pla

te

contains

the

oil

pump

pressure relief valve

and the o

il

cooler relief valve.

(See Fig.

29,) It is

mounted

on the outside

of

the

crankc

ase

at

the

left front of the engine.

The

func tion

of

the

oil

pressu re relief va lve

is

to

by-pass

excess oil directly

back

into th

e crankcase when-

ever

the

pressure

in the oil sy

ste

m exceeds

the

specified limits.

When

the

oil pressure

has

stabil-

ized, the spring tension w

ill

cont

rol

the

valve posi-

tion

to

maintain

normal pressure within specified

limits.

The relief valve plunger

and

spring on early

engines

are

located

in the oil p

ump

cover itself.

Inspection of

the

oil pres

sure

relief valve plunger

(Fig.

29-4)

and spring c

an

be

made

by removing

the rear

hex

nut

on the by-pass pla

te

housing.

Inspect the plunger

an

d bore for smoothness. Bore

diameter

is

.5615"

to .5630

". Plunger

diameter

is

.560"

to

.561 ". Two types

of

plungers were used ,

however,

plunger

part # 14732

is

the only one

which

will

be serviced since

the

two types are i

nter

-

changeable

in all engines

of

this model.

Free length

of

spring

is

2-11 /

32"

and,

when

compressed

to 1-21 / 32",

the

spring sh ou ld

exert

a force

of

1 0

to

11 Ibs. All of

the

pa rts should be

cleaned

and

reassembled with a new copper

gas

ket

under

the

nut.

The

operation

of

the

oil

cooler relie f valve is

to

by-pass

the

oil

through

the

by-pass plate

should

the

oil flow

through

the

coole r or cooler oil lines

be retarded. (See Fig.

29-6

to 10,)

In

this ma

nner

,

the

engine

would

continue

to receive lubr ication

independent

of

the

cooler's

operation

in

the

event

cooler obstruction occurs. The oil coo l

er

relief valve

incorporates a 9/ 16" steel

ball, held

against

a se

at

in

the

by-pass

plate

by a sprin g, which

has

a fre e

length

of 1-29

/ 32" and, when compresse d

to

1-

1/16",

should

exert

a force

of

2.1

to

2.4 Ibs. A

perforated

brass

cage

serves

as

a guide a nd

reta

iner

for

the

relief valve ball.

Inspection of

the

oil cooler relief valve assembly

can

be

made

by removing

the'

front

hex

nut

on

the

by-pass plate. Use a new copper

gasket

when

reinstalling

the

unit

.

On a few

of

the

early model engines, the relief

is incorporated in

the

oil cooler line.

If a more

detailed

inspection

is

indicated,

the

en

tire by-pass

plate

assembly

may

be

removed

from

the

engine

by

loosening

the

cap

screws which

attach

it

to

the

outside

of

the

crank

case. Us

e a

new

gasket

of

the

proper type between

the

by-pass

plate

ahd

crankcase

when reinstalling the housing

on

the

engine.

31

~~

'.'.'

XX

-INLET

MANIFOLD

The

manifold on

the 6A4-1S0-B3

and

B31

eng

ine

is

composed of seven m

ajor units:

(See

Fig.

30)

a co

st

distr

ibuting

zone, on

which

the

carburetor

is mount

ed; two a

luminum a ll

oy dis-

tributing

zone pipes, 1 -

5/8"

in di

ameter

, joining

the

distributing, zo

ne

to

the

inl

et

manifo

lds; two

cast

inlet manifolds, o

ne

to the even-

numbered

side

and

one to

the odd-numbere

d si

de

cylinder

ports; two

aluminum

manifo

ld

equalizer

pipes,

1 -1 /

4"

in

diameter,

joining

the inlet

manifolds,

o

ne

for

the

odd-cylinder side a nd

one

for the even-

cylinder side.

The

manifold of t

he mode

l 6

A4-165-

B3

is

com-

posed

of

units

similar to

tho

se on the model

6A4-

1

50-83

engines.

The

individual parts, howeve

r,

are

not

interch

angeable betwe

en the two models.

The

distribu

ting

zone pipes on the 165

hp

model

are

1-7/

8"

in

diameter.

The manif

old equa lizer pipes

are

1"

in

diameter.

Even though it is physically

poss

ib

le

to install

the

ent

ire induction manifold

system

for

one

model on

the other

model,

this

should NOT be

attempted.

Neither engine

will

function properly with

an

induction system

other

than

the

one

properly approved

and

specified

for it.

The

distributing

zone

is fast

ened

to

the

rear

end

of

the

cran

case

by

one

0'1

pan

mounting

stud

and

by two 1/

4"-

20 x

2-

1/

2"

hex

head cap

screws

through

the

tim

ing

case

into

tapp

ed holes

in

the

rear

crankcase

sur

face. A plain 5

/16

" shakeproof

was

her

is

used on

the

stu

d whi

le

1/4"

shak

epfoof

washe rs

are

used

under

the

ca p s

cr:ew. Some engines

use plain washers

under

the

cap

screw

heads

and

lacing wire. The distributin g

zone ..on

the

model

6A4-

165-83

engine

is

mounted

in

the

same

man-

ner

except

that

the

two 1/

4"-20

cap

screws

are

3"

long.

The

distributing

zone

pipes

are

joined

to

the

zone

and

manifold by inlet manifold flanges.

The

flanges

are

mounted

to

man

ifolds

at

one

end

and

the

zone

at

the

opposite

end

by 5/16"-18

x 5/

8"

hex

head

cop

screws, using 5/1

6"

shakep

roof

washers

under

the

screw head. Rubber packings,

which

are

a crush

fit

in

man

ifolds

and

zone,

are

held

in

position by

the

flange

s.

The

manifold

equal-

izer pipes

are

joined

to

the end of

the

manifolds,

using similar rub ber

pac

king

and

flanges,

as

well

as

the

same

size

cap

screw

and

shakeproof

washer.

The

equalizer

pipes a re joined

together

in front

of the

eng

ine by a fabric-reinforc

ed

composition

hose,

1

-1

/ 4" inside dia

mete

r,

2-1/ 2" long, secured

by two

adjustab

le hose clamps. A clamp

attached

und

er

the

hea

d of a

front

oil

pan

screw

and

tighte

ned with a # 10-

32

screw supports

the

weight of the fro

nt

equaliz

er pipe assembly.

The

hose connec

tion

on the model 6A

4-16

5-B3 is 1"

inside

diameter

by 2-1 /

2"

long.

The cast

inlet

man

ifolds are m

ounted

on

the

cyli

nder

inl

et

ports

by 5/ 16"-1

8 Allen

head

socket

sc

rews. Th e scre

ws are secured

in

position with

lacing wire, and

5/

16" plain washers

are

used

under th

e heads. Lat

er

mod e

ls

use 5/1

6"-18

slotte

d h

ex head

cap screws with 5

/16" shakeproof

6-

FIG.

30.

Inlet

Manifold

1.

Connecting

Hose

7.

Flange

a nd

Rubber

Pockin

g for R

ear End

2.

Supporting

Bracket

for

of

Runner

Front

Pipe

8.

Distributing

Zone

3.

Front

Manjfo

ld

E

qualizer

Pipes

9.

Flange

and

Rubber

Packin

g fo r Distribut ing

4.

Fl

ange

and Rubb

er

Zone En

d of Pipes

Packing

for F

ront

End

of

Runne

r

10.

Carburetor

5. Cyl i

nder Intake

Port

1

1.

Rea r Dist ribu

ting

Zon e

Gasket

Pipes

6.

Cast

Run

ner

Inle t

Manifold

washers. A composition

gasket

is used a t

each

cylinder inlet port between

the

manifold

and cylin-

der

matching

surfaces.

It

is of

greatest

importance

that

all sea ls,

gas-

kets,

and

connec tions in this manifold indu ction

system be proper

ly inst

alled.

The

system m

ust

be

sealed

against

the

entr

ance of unmetered

air

as

the

carburetor

will only supply fuel

in

proportion

to

the

air

flow that poss

es

throu

gh

its ven

tur

i

system; hence,

the

ent

ranc e of outside a ir at

atm

ospheric pressure into t

he low

er

pressure area

of

the

inside of

the indu

ction system

will

ca use

the

engine

to

overheat

due

to

a le

on

fuel mixture.

CA

UTI

ON : It

is

importc

nt

that

the

manifolds

be properly a

li

gne

d wi

th

the mounting

pads

on

the

cylinder

s.

If pro per a lign me

nt

is

not

obtaine

d,

manifo

ld leaks w

ill

occu r or a manifold

casting

may be

crac

ked wh

en

the

mou

nt

sc re

ws

are

tight-

ened

. To

obtain pro

per alignment, the cylind

er

hold-down

nuts

shoul d

not

be completely

tightened

wh

en

the cylinder

is

first

assembl

ed

on the

engine

.

Th

e manifold runne

rs

shou

ld

be temporarily

as-

sembled on t

he

cyl inders without

any gaskets

and

the mount

screws tigh

tene

d. T

he

cylinder hold-

down

nuts

shou

ld

then be tig

hten

ed

with the proper

torqu

e. The manifold runners should t

hen

be re-

moved for

lat

er asse mbly with ga

skets

.

32

7

XXI

- ACCESSORY GEAR

TRAIN

MAGNETO DRIVE

GEAR

AND

HUB

The

magneto

drive

gear

is

a steel,

30

tooth,

helical gear. (See Fig.

31

-2.) The

gea

r itself

is

machined

separately

from the hub.

The

hub

is

pressed into

the

gear

to form

an

assembly. A

Wood~

ruff key

and

keyway insure

that

the

proper rela-

tion between

hub

and

gear

teeth

is

maintained.

This gear

and

hub

are

furnished for service re-

placement

only

as

on

assembly.

The

hub

has

on

extended

shank

that

is

pressed into

the

hollow

rear

end

of

the

crankshaft.

The

hub

is

coated

with

an

anti

-sieze compound before being pressed into

the

shaft.

The

two

Woodruff

keys

that

position

the

starter

gear

on

the

outside of

the

crankshaft

extend

through

the

shaft

and

also position

the

magneto

drive

gear

hub

on

the

inside

of

the

shaft.

There

are

two

tapped

holes

in

the

gear

hub

that

furnish a

means

of

pulling

the

gear

assembly

out

of

the

shaft.

There

is

a hole

in

the

center

of

the

hub to

take

the

tachometer

drive gear.

The

mag-

neto

drive

gear

should be checked for

squareness

with

the

crankshaft

after

assembly.

The

maximum

permissible runout

is

.005"

total

indicator reading.

The

permissible

backlash

of

the

magneto

drive

gear

with

magneto

and

generator

driven

gears

is

.006" to .010".

MAGNETO DRIVEN

GEAR

The

magneto

driven

gears

are

aluminum

20

tooth helical gears. (See Fig.

31-3.)

The

inner

hub of

the

gear

has

eight

equally

spaced

recesses

machined

in

it. Also,

the

outside

face

of

the

mag-

neto impulse coupling

has

eight

recesses

machined

in

it.

When

assembling

the

gear

em

the

magneto

shaft,

hold

the

magneto

in

a vertical position with

the

drive

shaft

pointing

straight

up. Install

the

rubber shock absorbers

in

the

recesses of

the

im-

pulse coupling

and

then

slide

the

magneto

driven

gear

over

the

shaft.

Line up

the

gear

so

that

the

rubber shock absorbers form a drive between

the

gear

and

the

impulse coupling. Install

the

special

nut

and

pull

the

entire

assembly up to

the

proper

torque. Line up

the

hole

through

the

shaft

with

a hole

in

the

nut. Before

the

nut

is

safetied

with

a

cotter

pin,

the

magneto

impulse should be

checked for freedom

of

operation. Hold

the

mag-

neto

in a horizontal position

and

turn

slowly by

hand

in

the

normal direction

of

rotation.

The

im-

pulse pawl should

engage

the

stop

stud.

Further

turning should

cause

the

impulse

to

snap. If

the

impulse does

not

snap,

the

magneto

gear

should

be removed

and

the

gear

and

gear

spacer

checked.

When the

gear

is

assembled

against

the

shoulder

on

th

e ma

gneto

drive

shaft

without

the

rubber

shock

absor

bers

in

place,

the

spacer

on

the

shaft

should

protrude

.001" to .007" beyond

the

face of

the

gear.

The

permissible

backlash

with

the

drive

gear

is

.006"

to

.010".

GENERATOR DRIVEN

GEAR

The

generator

driven

qear

is

an

aluminum,

20

tooth helical gear

. (See Fig.

31

-1,) This

gear

has

eight

equally

spaced

recesses

in

the

hub .

When

assembling

the

gear

on

the

generator

, it

is

first

necessary

to

install

the

special

adapter

so

that

33

FIG.

31.

Ace.nory

Gear Train

1.

Generator

Driven

Gear

3.

Magneto

Driven

Gear

2.

Accessory Drive

Geor

4.

Tachometer

Drive

Gear

the

eight

equally

spaced

recesses

in

the

adopter

face away from

the

generator

body. This

adapter

is

keyed

to

the

generator

shaft

wi

th

a

#61

Wood-

ruff key. A rubber shock absorber unit with

eight

projections on

either

side

is

used

as

a drive connec-

tion between

the

gear

and

the

generator

shaft.

Une

up

the

recesses

in

the

gear

with

the

shock

absorber

projections

and

install special

flat

washer

and

nut.

Pull

the

entire

assembly up

tight

and

safety

with a

cotter

pin. Engines with

the

15

am-

pere

generator

have

the

individual rubber

shock

absorbers

and

installation

will

be

eased

by holding

the

generator

in

a vertical position with

the

shaft

upward while assembling. The moulded shock

ab-

sorber unit

and

the

individual shock absorbers

are

not

interchangeable

due

to

the

different

overall

thicknesses.

CAUTION: Inasmuch

as

the

aluminum

helical

tooth

gears

look very much

the

some, it

is

most

important

that

proper precautions be token

to

avoid a mix-up

of

the

gears. The

magneto

and

generator

driven

gears

are

not

interchangeable.

The

permissible

backlash

with

the

drive gea r

is

.006" to .010".

TACHOMETER DRIVE

The

tachometer

drive

gear

is a small

heat-

treated

steel, 12 tooth,

spur

gear. (See Fig.

31-4.)

This

gear

is

made

with a short .1885"

to

.1890"

diameter

shaft

that

is

a press fit

in

the

hole in

the

magneto

drive

gear

. An assembly composed

of

a

cylindrical housing, a sleeve, a

tachometer

drive

connector,

the

24

tooth

tachome

ter driven gea

r,

and

a packing complete

the

tachometer

drive. The

housing

containing

this assembly

is

a press

fit

into

a hole

near

the

center

of

the

rear

timing

gear

case.

Two

1/4"-20

x

1/2"

cap

screws

and

shakeproof

washers secure

the

housing

to

the

case. The

per-

missible

backlash

between

the

tachometer dri

ve

and

driven

gears

is

.001"

to .003".

STAR

TER

GEAR ASSEMBLY

The 103

too

th starter

ring ge

ar

is

shrunk

onto

shaft

is

coated

with

an

anti-sieze

compound

be-

a forged s

teel hub

to form a

permanent asse

mbly.

fore

the

gear

is

assembled.

The

gear

is

positioned

(See Fig.

50

-1

, p.) The hole

in

the

gear

hub

has

a

on

the

shaft

by two # 16

Woodruff

keys

and

is

diamete

r of 1.996

8"

to 1.9975"

. Th is produces a

secured

by a

spanner

nut

and

tab

lockwasher.

The

.

004"

to .0052

" shrink fit on the 2.00 1

5"

to

sp

anner

nut

is

brought

up

as

tight

as

possible.

The

to

heat

the gear

assembly to 2

00°

to

250°F

to

as-

wi

th

the

crankshaft

after

assembly.

The

maximum

semble

it on

the crankshaft.

The

end

of

the

crank-

permissible

runout

is

016"

total

indicator

reading.

2.0020" di

ameter

cra

nkshaft

end

. I t

is

necessary

starter

gear

should

be

checked

for

squareness

XXII-

IGNITION

To

# 5 Cyl.

To

# 5 Cyl.

Bottom

Plug I

To

# 6 Cyl.

Top

Plug

To

=#

6

CyL

I I

Top

Plug

To # 3

Cyl.

I I

To

#"

3 Cyl.

Bottom

Plug # 4

Cyl.

Top

Plug

f_}l

To

fl

I r

To

p

Plug

To

#"

I Cyl. I

l

BotiomPlugl

I I I

To

#

2Cyl.

Top

Plug

I

II

IT I

Top

Plug

I

II

,I I

Plates

,----

1---

I

I

r--

I

I

I

-j

I

I

I

I

I I

I

I

I

I I

I

I

I

I I

I

I

I

I I

1

I

I

I

I

I

I

I

I

I

I I

I

L

I

J I

,

I

I

L

__

__

J

ist

ributor

Plates

Left

Mag

neto

Right

Magneto

FIG.

32.

Wiring Diagram for

6A4-150-B3

and

B31

Engines

Engine Firing Order

1-4-5-2-3-6

34

T'o # 5

Cyl.

• To :# 5

Cy

I.

-,

Top Plug

r-_Bottom~lug

1To #: 6

Cyl.

I

To

'# 6 Cyl.

r-------......r--

I I Top

Plug

I I

Bottom

Plug

I

To

# 3 Cyl. I

I To # 3

Cyl.

I

I Bottom Plug

I

I

I

To

# I Cyl.

I

I To # 4

Cyl.

I I

Top

Plug

I I

I I Bottom Plug I I I

I I

I I

I I

I

I I

II

II

I I

'-t--

L

__

@-_

J

Left

Magneto

I I I

To

#:

2

Cyl.

I I I

Top

Plug

I

I

I I

I

L'L----

I

I

-':

I

~

I

\!)~4

0 I I

I

' @

I

I

I I Top Plug

, :

I I

I I

To

#"

1 Cyl.

I I Top Plug

I I

I I

I I

, ,

I I

II

~

I I

---......

I

I

I

Lj--w

0

4

@

I

I

I

L

@-

-~

Rig

ht Magneto

I

To # 4 Cyt

'

I

I

Bottom

Plug

I

I

I

I

I

I

I

I

To

#"

Z.

Cyr.

,

Bottom

Plug

I

I

I

I

'-{-I

I

I
I

FIG.

33. Wiring Dia....

..

A4-165-

J

bii

...

Engine Firing Orcler

'-4-5-2-3-6

The

ignition for

the

6A4-150-B3

and

831

engines

is

supplied by two LA-6 Eisemann

magne-

tos (See Fig.

34),

mounted

on

the

rear

timing

case.

The

high tension

current

is

carried

from

the

distributor,

which

is

Incorporoted in

the

magneto,

to

the

spark

plugs, by 7 mm. high

tension

cable,

containing

19

strands

of

tinned

copper

wire.

The

ignition for

the

model

6A4-165-B3

and

a few

of

the

later

model

6A4-150-83

engines

is

supplied

by Bendix-Scintilla S6RN-21

magnetos.

The

Bendix

and

the

Eisemann

magnetos

are

similar

in

principle

of

operation,

and

the

descriptive

mformation

below

appl ies

to

both.

Wiri ng

diagrams

for

6A4

-1S0-B3

and

831

and

the

6A4

-165-

83

engines

are

shown in Figures

32

and

33 respectively.

MAGNETOS - PRINCIPLES OF OPERATION

The

LA-6

and

S6RN-21 model

aircraft

magnetos

are

of

the

conventional

high tension type.

They

cons i

st

basically

of

a closed

magnetic

circuit

in-

cluding a rot

ating

magnet,

a coil

incorporating

a

primary

and a secondary

windingl a

breaker,

a

condenser,

and a jump

spark

high

tension

dis-

tributor.

FIG. 34.

LA-6 Magneto

1.

Magneto

2. Imoulse Coupling

3. Drive

Adapter

4.

Magneto

Dnven

Gear

5. Rubb

er

Drive Shock

Aqs orbers

6. HoldinQ

Nut

35

TO SMRK PLUGS

8

26

3

22

25

~--28

---+-

-HN~

5

--.-.....-~~1

1

6------l

~

~

-----~

--------------

~

TO

MAGNETO

SWITCH

FIG.

35. Schematic Diagrom

of

Electric and

Magnetic

Circuifl

A.

High Tension Cable

8.

Breaker

Com

13.

B.

Hi

gh

Tension Termina l

15.

{

con-Se

condooy

Winding

2. C

oi

I Contact

or

22

.

12.

Coi l- Pri

mary

3.

Ca rbon Brush

and

24.

Winding

Sp

ri

ng

Cail-Care

25.

5.

Distribu tor Rotor
Electrode

6.

Distributor Pla

te

El

ectr

ode

The

magneto driv

e shaft carrie

s a two-pole

alnico

magn

et fitte

d with la min a

ted

pole pieces.

This

magnet assembly

rot

ates in t

he

tunnel

of

the

main

housing which inclu

des

cast-in

laminated

pole

shoes

. These po le shoes

are

bridged

at

their

upper

end

s by

the

lami

nated

coil c

ore

to

complete

the

magnetic

circui t.

Referring to the sc

hematic

diagram

of

the

mag-

netic circuit

(Fig. 35) , it

is evi

dent

that

the

direc

-

ti

on

of flux through

the coil

core

is

reversed twice

for

each

revoluti on of

the magn

et

rotor.

This gene

rated current rep

rese

nts

energy

stored

in

the

magnetic

circ uit by

distorting the

magnitude

and

direction

of

flux from its normal condition.

Interruption of t

he

prima

ry

cur

rent by opening

of

the

cont

act

breaker rel e

ases

this

sto

red

energy

by

allow ing the flux

to cha

nge

rapid

ly

to

its

normal

state.

This rap

id

change of

flu x through

the

pri-

mary

winding induces t

he requir

ed high

voltage

-

surg

e in

the

sec

ondar

y wind ing.

T

he design

of

the cam is

such that it

opens and

cl

oses

the

brea ker

in

proper rel

atio

n to

the

posi -

tion of the ma

gne

t rotor, th

ereby produc

ing

the

maximum o

btai

nab

le

valu

e of high volta

ge

surge

.

T

he condenser

is

connected in

parallel

with

the

bre

ake

r c

onta

cts in order

to suppre

ss

contact

arc-

in

g when

the

prim

ary cur

rent

is

interrupt

ed.

The

hig h tension distribut

or consi s

ts

of a

jump

gop

type of rot

ating switch properly

geared

to

the

ma

gne

t rotor. Th

is

serves to di

stribu

te

the

high

volta

ge

surges

to

the prop

er cylinder

at the

correct

t ime.

26.

28

.

Hi

gh Tension Terminal

Magn et Rot

or

Distributor

Cam
Brea ker Assembly
Pinion

Ge

ar

Condens

er

Breaker Con

denser

Lead

29.

Grou d

Ter

minal

The magne

to

is " t

urned off"

by

connecting

the

gro

und terminal

to ground thro

ugh a

suitable

igni-

tion

switch . Gr

oun

ding this te rminal

short

circuits

the brea

ker,

thus

ma king

it

impossible for

the

apening

of

the .conta

ct points to

interrupt

the

pri-

mary

curren

t.

IMPULSE

STARTER

ON THE LA-6 A

ND

S6RN-21 MA

GNE

TOS

The impu

lse

starter

is

an automatic

device,

which

ope

ra tes only

during

engine

starting,

and

serves a two-fold purpose. I t

automatically

retards

the

tim

ing

of

the

ignition spark

to

prevent

engine

"kickin

g" when

starting, and it

intensifies

the

s

pa k to

insure

easy

starting.

At

starting

speeds,

the

impulse

starter

auto-

matically locks t

he

magn

et

rotor twice

during

each

revo lution. W it h the rotor blocked,

the

magneto

drive memb

er continues

to

turn

with

the

engine

Windi ng up t

he

impulse

starter

spring.

When

the

spring

is

com

pletely wound u

p,

the

starter

auto-

mat

icall y unlocks the rotor and

the

unwinding

of

the

impulse sta

rter

spring

rapidly rot

ates

the

mag-

net

rotor

to

its normal position. Th

is

rapid

rotation

of the mag

net rotor causes a

spark

of

high

intensity

to

be

generat

ed

at

a ti me

later

than

normal.

When the engi ne

sto

rts

and

the

magneto

comes

up to speed, the impulse coupling

latches

are

moved by cent

rifugal

action

to

their

disengaged

position.

The

magn

eto

then

continues

to

operate

in

the normal mann

er.

36

0 -

-------

FIG.

36.

LA-6 Magneto

Longitudinal Section

1.

Cover P

late

8 .

Breaker

Cam

15 .

Magnet Rot

or

2.

COM Con

tactor

9. Housing

Ventilat

or

1

6.

End

Plate

3.

C

orban

Brush

and

10

. Ball

Bearings

17.

Coble

Plate

Spri

ng

11. Distri b

utor

Bear

ing

18.

Oil Seal

4.

Distributor

Spring

12. Coil

19

. Sli

nger

5.

Distributor

Rotor

1

3. High

Tensi

on Terminal

20.

Rotor

Shaft

Electrode

14.

Housing

21 . Cover

Ventilator

6.

Distributor

Plate

Electrode

7.

Adopter

EISEMANN MAGNETOS -

MINOR

The breaker contact

po in

ts should

be clean

and

free

from

oil. If the

con

tac

ts appear

in good condi -

INSPECTI'

ON

(ON ENG INE)

tion,

it should

not

be nec

essa

ry to che

ck

bre

aker

Remove

the

two screws which hold

the

ca

ble

timing. When,

however, the co

ntacts

show

signs

of

plate

to

the

end

plate

(Fig. 36-1 6

). Als

o re

move

wear,

the breake

r timing

should

be readjusted.

the

end

plate

(16).

The entire distributor sect ion

To

odjust the break

er

contacts,

turn

the

engi

ne

of the

magneto

may

then

be

removed to al low

crankshaft unt

i I

the cam

follower be

ars

on

the

top

inspection

of

the

magneto

operating comp

onent

s.

of

# 1 cylin

de

r ca m l

obe, thus giving

maximu

m

Care

should

be

taken

in removing the dist

ributor

conta

ct poi

nt

separation

. Loosen

sl ight

ly

the

two

section

to

pull

it

straight

back

from

the main

hous

-

scre ws which

secure

the break

er asse

mbly

in the

ing until dowels,

distributor

rotor, a nd coi l

con-

e

nd

pla te, and by

means

of the

breaker

adjusting

t

actor are

in

the

clear before

attemp

ting

to

swing

e

ccentric

(Fig. 37

-27),

set the con

tact

for a

it

to

the

side.

s

eparatio

n of from .

019"

to

.02

1". (See Fig.

40.

)

Wipe

out

any

accumu

lat i

on

of

forei

gn

material

Retighten the

breaker

securing

screws

and

recheck

inside

the

distributor

plate wit

h a cloth

moist

-

contact separa

tion. Care

should

be exerc

ised that

ened

in

carbon

tetrachloride.

Be

sure

that

the

setting gage

is free from dirt and

oil.

carbon

brush

and

the

coi I connector a re free. I

n-

ALWAYS C

HE

CK THE MAGNETO TO E

GINE

s

pect

visually

the

coil, distributor

rotor and gear,

TIMI

G

WH

E EVER ADJU

STMENT

OR RE-

coil

and

breaker

leads,

and brea

ker

assembl

y.

PLACEMENT OF

TH

E BREAKER POI NTS

IS

I f

the

interior

of

the mag

neto

appea

rs e

xces

­MADE.

sively oily,

the

magneto

shou

ld

be

removed fr

om the

engine

for

thorough

cleaning and

poss ible replace-

Rea

ssemb

le

the dist

rib utor

sec

tion

end

plate,

ment

of

the

oil seal (Fig. 36

-18). The d

istributor

making sure that

the

carbon

brush

is

prope

rly

r

otor

and

gear

should

be

free

, but without

exce

ssive

I·o

cated

and

not broken,

and that

the

dowels en

ter

backlash

or

end

play

.

sq

ua

rely.

37

FIG.

37.

LA-6

M.peto

Tr'tInlY.'"

Section

22.

Distributor

Gear

27.

Breaker

Adjusting

Eccentric

23.

Breaker

Points

28.

Breaker

Condenser

Lead

24.

Breaker

Assembly

29.

Ground

Terminal

25.

Pinion Gear

26.

Condenser

MAGNETO

TIMING

CHECK

To

check

the

timing

of

the

magnetos

when

they

are

installed

on

the

engine,

proceed

as

follows.

Turn

the

crankshcft

in

the

normal

direction

of

rotation,

clockwise,

as

viewed from

the

rear

end

of

the

engine.

Observe

the

action

of

the

inlet

valve

on

# 1 cylinder.

When

the

inlet valve

has

been

de-

pressed by

the

lifter

rod

and

returned

to

the

closed

position by

the

valve spring,

the

# 1 cylinder

is

on

the

compression

stroke.

Continue

to

turn

the

crank

-

shaft

until

the

impulse coupling

is

released.

This

will

occur

at

approximately

top

dead

center

of # 1

cylinder

and

can

be identified by

an

audible

click

at

the

magneto.

Turn

the

crankshaft

in

the

reverse

direction

of

normal

rotation

until

the 28°

mark

on

the

crankshaft

flange

has

passed

the

timing

pointer

by a few

degrees

or

far

enough

to

compensate

for

backlash

in

the

gears.

Do

not

turn

the

crankshaft

more

than

this

amount

as

the

impulse coupling

will

become

reengaged,

giving

an

incorrect

breaker

point

position.

Remove

the

magneto

distributor

cover

to

observe

the

action

of

the

breaker

points. Using a

timing

light,

.0015"

feeler

stock

or

cellophane

to

deter-

mine

the

breaker

point

opening,

turn

the

crank-

shaft

in

the

normal direction

of

rotation

until

the

28° mark

is reached. (See Fig. 39,)

The

breaker

points

on

the

magneto

should be

just

opening

at

this

position

of

the

crankshaft.

If

adjustment

is

necessary

to

obtain

the

correct

setting,

it

must

be

made

by moving

the

magneto

in its

flange

slots.

Do

not

adjust

the

timing

of

the

magneto

points in

relation

to

the

crankshaft

position by moving

the

points

through

the

eccentric

adjusting

screw. I t

is

always good

practice

to

check

the

breaker

points

maximum

opening

as

outl ined in

the

section

on

minor

inspection

(Page

37)

before

checking

the

magneto

timing. (See Fig.

40.)

On

the

mode l

6A4-150-B3

and 831 engines, a

2°

tolerance

is

allowed

on

the igni

tion t imin g so

that 28°

to 30° b

efore

top d

ead

cen

ter

is

pe rmissi-

ble.

The

left

magneto

setting

is

at 28°, but

it

is

often

possible to decreas e the "

magn

eto drop" by

s

etting

the

right

magneto

to

29°

or 30°.

BENDIX - SCINTILLA MAGN

ETO

The

sections

above

on

minor insp

ect

ion

and

magneto

timing

also

apply

in most

part

to the

Bendix -Scintilla

magn

etos on

the

mod

el 6A4-165-

83

engine. On

the

Scintilla

magneto,

however, it

is

necessary

to

remove the brea

ker cover

to obse rve

or

adjust

the

breaker

points.

The

points

are

ad-

justed by loosening

the

set

screw in the slott

ed

breaker

arm.

The high tensi on

cable contact

sockets

may

be inspected for moisture by remov-

ing

the

high tension

grommet

retainer plate.

CAUTION:

Do

not,

under

any

circumstan

ces,

remove

the

five screws which hold the two sect ions

of the

magneto

together,

while

the

magneto

is on

the

engine.

To

do so would

disengage

the

distribu-

tor

gears,

causing

the distributor timing

to

be

"Iost"

and

necessitating

complete

removal and re-

timing

of

the

magneto.

SPARK PLUGS

The

approved

non-shielded

spark

plug for all

the

engine

models covered in this manual is

the

Champion

J-10.

The

approved shielded s

park plu

g

is

the

Champion

C-1

OS.

The

spa

rk

gap

setti

ng for

both

type plugs

is

.014"

to .018".

Spar plugs

should be screwed

into

the

cylinders wit h

the

fingers

only until

they

are

snug

to avoid crossing the

threads.

They

should

be

tightened with a tor

que

wrench

to

a value

of

180

to

240

in. Ibs.

FIG. 38.

LA-6

Magneto

Timing Marks, Internal Parts

1. Magneto

Ground W ire

2.

Mag

net

o B eaker Points

3. Ma

gnet

o Condenser

4.

Magnet

o Gear Timing

Ma rks

38

FIG.

39.

Setting

Timing

Morks

on Propener Flange

MAGNETOS - INSTALLATION ON MODEL

6A4-150-B3

AND

831 ENGINES

Remove

the

valve cover from # 1 cylinder,

left

rear

of

engine,

to

observe

the

valve

action.

Rotate

the

crankshaft

in

the

normal direction, clockwise,

as

viewed from

the

rear

of

the

engine.

Observe

the

# 1 cylinder

inlet

valve

(left-hand

valve

when

fac

-

ing

the

cylinder

head) . When

the

inlet

valve

has

been

depressed

and

returned

to

its

normal

position,

the

# 1 cylinder

is

on

the

compression

stroke.

Con-

.

tinue

rotating

the

crankshaft

in

the

same

direction

until

the

28°

magneto

timing

mark

on

the

outer

rim

of

the

crankshaft

propeller

flange

at

the

front

end

of

the

engine

is

in line with

the

porting

line

formed

by

mating

surfaces

of

the

two

crankcase

halves (See Fig.

39).

The

engine

is

now in

correct

timing

position to install

magnetos,

i.e.,

28°

before

top

dead

center

of

# 1 cylinder

on

its compression

stroke.

Install

the

spiral

magneto

drive

gear

complete

with

rubber

cushion

drive,

making

sure

the

eight

rubber

projections

engage

pro

perly

in

the gear hub

and

in

the

counterbore

on

the

face

of

the

impulse

coupling

on

the

magneto.

Remove

the

distributor

cover

on

the

magneto

to

expose

the

distributor

electrode

and

breaker

points.

With

the

magneto

hand

-held in a

horizontal

posi-

tion,

turn

the

rotor

shaft

in

the

direction

of

normal

rotation

and

snap

the

impulse coupling several

times

to

check

its

operation.

Next,

turn

the

rotor

in

reverse

direction

to

normal

rotation,

to

avoid

engaging

the

impulse

unit,

until

the

center-line

mark

on

the

rotor

gear

is ind e

xed

with

the

punch

mark

on

the

breaker

com

gear. The

distributor

rotor

electrode

is

now in

the 7 o'clock

position

and

is

in

position

to

fire # 1 cylinder (See Fig.

38).

Install a

gasket

on

the

magneto

pod

of

the

rear

timing

case

and

install

the

magneto

adapter

plate.

Install a

second

gasket

between

this

adapter

and

the

magneto

itself. Now instqll

the

magneto

with

the

timing

case

studs

in

the

middle

of

the

magneto

flange

slots. Install

the

special

5/16"

plain

washers

and

5/16"-24

elastic

stop

nuts,

leaving

the

nuts

loose

enough

so

th t the

magneto

may

be moved

in its

slots

by a

slight

tap

of a soft

mallet.

Using a

timing

lightf .001

5"

feeler

stock

or

thin

cellophane

to

check

the

point

opening,

tap

the

magneto

until

the

points

are

just

separating.

With

the

magneto

housing in

this

position,

tighten

the

stud

nuts.

MA

GNETOS - INSTA LLAT ION ON THE MODEL

6A4-165-B3

ENG INE

The magnet

o on this

engine

is

installed in a

ma nn

er

sim il

ar

to that

described in t

he

section

abo ve with t

he

following exce

ptions : The 32° tim-

ing

mark

is line

d up with the

crankcase

centerline

as sho

wn

in Fig. 39. Remove

the

plug from the

in

spe

ctio

n hole provided a t

the top

and

rota

te

the

magneto

until

the cham

fered too

th

with a white

poi

nt

ma rk

is near the

center

of

the

hole. The

breaker cov

er

should be removed so

tha

t t

he

point

s

ma

y be observed. T

he magneto

is

insta lled

on

the

eng

ine and c

heck

ed for prop

er

timing

as

described

above.

FIG. 40.

Settilll

M.lneto l re

eker

G.p

39

2

XXIII-

CARBURETION

10

9

MA-3SPA Carburetor

1. Mixture Control

8.

Idle Speed

Adjustment

linkage

and

Stop

Screw

2.

Fuel Inlet

9.

Throttle

Stop

3.

Fastening Screw between

10.

Throttle

Butterfly Valve

Upper

and

Lower Bodies

1

1.

Idle Mixture

Adjust-

4.

Accelerating Pump Body

ment

Screw

5. Fl

oat

Bowl

Drain Plug

12. Accelerating Pump
linkage

6.

Float

Bowl

7.

Throttle

Arm

The

model MA-3SPA Marvel-Schebler

carburetor

used

on

the

6A4-150-B3

and

831 engines

is

of

the

float

type

and

incorporates

an

accelerating

pump

and

a mixture control

unit

. (See Fig.

41,)

The

carburetor

is

made

up

of

two

major

units--a

cast

aluminum

throttle

body

and

bowl

cover,

and a cost

aluminum

fuel bowl

and

air

entrance.

The

model

MA-4-5

carburetor

is

used on

the

model

6A4-165-

83

engine.

The

model MA-3SPA

and

MA-4-5

car-

buretors

are

very similar

except

for

the

size

of

the

various parts.

The

information below appl ies

to

both

models. Fig.

42

is a diagromatic

picture

show-

ing all

of

the

operating

parts.

ADJUSTMENTS AND PRECAUTIONS

The

only

adjustment

that

is

ordinarily

made

on

the

carburetor

while it

is

on

the

engine

is

to

obtain

proper idle conditions.

The

engine

should be thor-

oughly warmed up before making

the

idle

adjust-

ment.

The

idle speed

adjusting

screw (Fig.

41-8)

should be

set

so

that

the

engine idles

at

approxi-

mately

550

RPM.

The

idle mixture

adjusting

screw

(Fig.

41-11)

should be

turned

out

slowly until

the

engine

IIrolls" from richness,

then

turn

the

screw

in

slowly until

the

engine

"lags"

or runs

"irregu-

larly" from leanness. This

step

will

give

an

idea

of

the

idle

adjustment

range

and

of how

the

engine

operates

under

these e

xtre

me idle mixtures . From

the lean setting, tu

rn the nee dle o

ut slo

wly

to

the

richest mixture

th

at will

not caus

e the

engine

to

roll or run unevenly. This adjustme

nt will in

most

cases give a slightly slow

er

idle speed

than

a lean

er

mixture

adjustment,

with th e

sam

e throttle stop

screw

setting,

but it w

ill

give

the

smoothest

idle

operation. A ch

an

ge

in

the

idle mixture will

chan

ge

the

idle speed

and

it may be necessary

to

read just

the

idle speed wi

th

the

th rottle stop scre w to

the
desired point. The idle adjusting needle should be
from 3

/4

to 1

tur

n from its

seat

to give a satisf

ac­tory idle mix ture.

This

proced ure

is the

same

on both

the

MA-3S PA

and

the

MA-4

-S ca rbu retors.

The

idle mixture a

d-

justing screw on the MA

-4-

S model is in the

sam

e

position

as

sho

wn

in

Fig.

41

-1

1,

but

it

is arrow

shaped

to ind

icate the

adjus

tment position.

CAUTION : C

ar

e should be

tak

en not

to

damage

the

idl

e needle

seat

by turning

the

idle adju

sting

needle too tightly

against

the

seat,

as

damage

to

this

seat

will

make

a satisfactory

idle adjustment

very difficult to

obtain

.

FLOAT HEIGHT

(FIG.

42-3

) :

The

float

height

is

set

at

the

factory,

and

can

be

checked

by remov-

ing

the

throttle

body

and

bowl cover and

float

as-

sembly.

The

carburetor

is

turned

upside down.

The

proper position

of

the

floats on

the

MA-3SPA

should be 7/

32"

from

the

bowl

cov

er

gasket

to

the

closest

surface

of

the floats. On

the

MA-4-S

car-

buretor

this dimension

is

13/

64". Be

sure to c

heck

both floats to the prop

er

dimensions,

making sure

that

the

floats are parallel

to

the

bowl cover gasket.

When

the

ca rburetor

is

disassembled for clean-

ing,

extreme

care

should be

taken

not to

enlarge

or

damage

any

of

the

jet

holes. Damage or enlarg e-

ment

of

the

jets wi

II

change

the

met

ering

charac-

teristics

af

the

carburetor

and

affect

engin e

opera

-

tion. A new

gasket

should be used between

the

two sections of

the

carburetor

when it

is reas-

sembled.

40

THROTTLE:

FLY

~%==:::;;zs:::/r

./

PRIMARY

IDLE

OELI

VERY

/

/'

SECONDARY

IDLE:

DEUV(

~

SECOND-'

RY

IOLE

AIR

VENT
HRTIARY OLE DELIVER!
TERTIARY

OLE

AIR

VEN.I

THROTTLE BARREL

AIR

VENT

SCREEN

FuEL

C"1ANNEL

FIG.

42.

SCh

.....

tk

Dnw

....

of

the

MA-JSPA

C.

...

.,N....

CAUTION: Care must be taken when

reassem-

bling

th

e mix

tur

e m

etering

valve assembly

to

see

that

the

met

ering valve pilots properly into

the

valve body. (See F

ig.

4.)

The

metering valve

is

actuated

by a flexible

shaft

and it

is

possible for

the va lve to be assembled w

ithout

sliding properly

into the

va lve body. I f this occurs,

the

carburetor

will meter extremely rich.

USE

OF MIXT

URE

CONTROL IN FLIGHT: T

he

mixture c

ontr

ol

should n

ot

be used u

nder

3,000

feet. Wh

en adjustin g the mixtur e c

ont

rol

for

alti-

tudes higher th an 3,

000 feet

, move

the

control in

and

out slowl

y,

with

the

throttle

at

cruising position

until the highest RPM

is

attai

ned. The ca rburetor

mixture wi

ll

then

be correctly adjus

ted

for

that

t

hrott

le position and l

oad

at that pa r

ticular

altitu

de.

CAU

TION: Always have t

he mixt

ure co nt rol in

the full

rich position wh

en

coming in f

or

a landing,

.so that if fu

ll

power

is

required in

an

emergency

near

th

e ground,

the

engi

ne

will

operate

satisfac-

torily and

will

not over-heat because of too lean a

mixtu

re.

ST

ARTING-

CO

LD ENGINE:

At

air te

mpera-

tures of freezing

or

above, two

or

three strokes

of

the

throttle

should prime the engine sufficiently

for easy

sta

rting.

When

the

engine

is cran

ked with

the

starter

and with t

he

thro

ttl

e cracked sli ght

ly

ope n, it should s

tart

immediately.

At

tem

peratu

res

below freezing down to abo ut 10°

F,

three strokes

of

the engine pri

mer

in addition to the three strokes

of

the throttle shou

ld

be used. After the engine

initia

lly st

arts,

occasional ope

rat

ion

of

the

primer

may be neces

sar

y during t

he

first

30

seconds of

operation. At

te

mpe

ratures below

loaF

, additional

prim

in

g m

ay

be necessary. The mixtu

re

contr

ol

should be in the full rich position for all

starting

attempts.

If

the start

er

fails to

turn th

e engine on

the first or second try, the engine should be

turned

through a few ti mes by h

and

with the ignition

off

and

the

sta

rter

again

tri ed. If

the

star

ter still fails

to

cr

ank the engine, the

batter

y should be checked

to see if it

is adequ

ate

ly

charged.

C

AUTIO

N: It

is

important to lock

the

prim

er

securely afte r using to preve

nt

fuel leakage into

the indu

ct

ion system and

improper engi

ne

opera-

tion.

START

ING-

HOT ENGINE:

With

the

mixtu re

cont

rol

in

the full rich position and the throttle

cl

osed, the engine should st

art

immedi

ately when

cranked. No priming is necessary when

the engine

is

hot rega

rdless of the outsi de

air

tem

peratu

re.

41

XXIV

- GENERATOR

AND

VOLT

GE

REGULATOR

3

FIG.

43.

Ge" rotor

1. Frame

and

Field

2.

Commutator

3.

Drive

Shaft

4.

Armature

The

generator

is

Q device for

changing

me-

chanical

energy into electrical energy. It consists

of

four main subassemblies.

These

are:

The

trame

and

field,

the

commutator

end

head,

the

drive

end

head

and

the

armature

assemblies. (See Fig. 43. )

The

frame

and

field consists

of

the

frame

which

supports

the

components

of

the

generator,

the

pole

shoes

and

the

field coils.

The

coils supply

the

mag-

netic field which

is

necessary for

generating

elec-

tricity;

the

pole shoes

and

frame

supply

the

path

for

the

magnetic

field.

The

commutator

end

head

supports

the

brush holders

and

brushes

that

are

needed

to

conduct

the

electricity from

the

revolv-

ing

armature.

A ball

bearing

in

the

commutator

end

head

supports

Qne

end

of

the

armature

shaft.

The

drive

end

head

includes a ball

bearing

which

supports

the

drive

end

of

the

armature

shaft.

The

armature

consists

of a soft

iron core, a

commutator

and

the

windings, which

are

wound in slots in

the

core

and

are

connected

to

the

commutator.

The

commutator

consists

of a number

of

copper

seg-

ments

insulated from

each

other

and

trom

the

armature

shaft.

The

voltage

regulator

is

a device

that

regulates

the

generator

current

and

vol

tage

output

to

the

battery

and

electrical units.

It

protects

the

genera-

tor

from overload

and

the

battery

from overcharg-

ing. (See Fig. 44.>

It

also

acts

as

a reverse-current

relay

to

prevent

battery

current

from flowing

bock

through

the

generator

when

it

is

not

operating,

causing

the

battery

to

discharge.

If

the

generator

is

not

charging

properly, all

connections

and

wiring from

the

generator

to

the

voltage

regulator

and

the

battery

should be

checked.

The

connections should be dry

and

tight

and

the

wiring should be free from frayed

spots

or

cuts. If

the

wiring

and

general condition

of

the

42

generator

is

satisfactory,

the

trouble

may

be

in

the

voltage regulator. Ordinarily,

the

voltage

regulator

is

not

serviced

but

is

replaced by a new regulator

of

the

proper type.

A

low

charging

rote

and

a fully

charged

battery

indicate

normal regulator

operat'on.

A discharged

battery

will

normally produce a high

charging

rote.

The

electrical accessories

may

be serviced

in

an

engine

shop

that

has

complete electrical repair

and

testing equipment. Usually

the

most

satisfac-

tory procedure, however,

is

to

take

the

accessory

needing service to a registered service

station

that

handles

the

make

of

equipment

involved.

CURRENT

REGULATOR

--GEN

-BAT

fiG.

44.

V

Ito

• Rqulator

xxv -

ST

ARTI

G

MOTOR

FIG.

45. Stortln, MDtor

1. Frame

and

Field

2. Armature

3.

Commutator

The

starting

motor

is

designed

to

crank

the

engine

when

the

starting

switch closes

the

circuit

between

the

storage

battery

and

the

motor. I t con-

sists

of

five main subassemblies which

are:

The

frame

and

field,

the

armature,

the

commutator

end

head,

the

pinion housing or drive end

head

and

the

Bendix drive. (See Fig.

45.)

The

frame

and

field consists

of

the

frame which supports

the

com-

ponents

of

the

motor,

the

pole shoes

and

the

field

coils.

The

coils supply

the

magnetic

field which

is

necessary for producing torque;

the

pole shoes

and

frame supply

the

path

for

the

magnetic

field. The

armature

consists

of

a soft iron core, a

commutator

and

the

windings which

are

wound in slots in

the

core

and

are

connected

to

the

commutator.

The

commutator

consists

of a number

of

copper seg-

ments

insulated from

each

other

and

from

the

armature

shaft.

The

commutator

end

head

supports a bearing

and

four brush holders

and

brushes.

The

Bendix

drive

is

an

automatic

clutch

that

engages

the

4.

Drive

Shaft

5. Bendix Drive

cranking

motor with

the

engine flywheel when

the

motor

cranks

the

engine

and

disengages when

the

engine

starts

. I t consists

of a threaded

sleeve

fastened

to

the

armature

shaft

through a drive

spring,

and

a pinion mounted on

the

threads

of

the

sleeve.

When

the

starting

circuit

is

closed,

the

armature

revolves, turning

the

sleeve within

the

pinion,

and

forces

the

gear

forward, meshing it

with

the

flywheel

gear

. The sudden shock of mesh-

ing

is

absorbed by

the

spring.

When

the

engine

starts,

the

pinion

is

driven

faster

than

the

sleeve

and

is

forced

back

along

the

threads,

automatic-

ally unmeshing it from

the

flywheel.

The

starter

ordinarily requires very little servic-

ing. Brushes should be replaced when worn

to

half

their

original length.

The

starter

should be dis-

assembled

and

inspected

at

300

hours. Any worn

Bendix drive

parts

should be replaced. The

arma-

ture

shoft

should

be

lubricated sparingly with light

oil

before

it

is

reassembled.

43

XXV I - E G

INE

ASSEMBLY

The following proce

dure

is inte

nded to serve

as

a guide

in

assem

bling the 6A4 -

150-B3

and

631

and

6A4-16

5-63 engi nes

after

they

have

receiv

ed

a complete overhau

l.

The me

thod

outlined

is

similar

to

the

procedure used when the en

gines

were orig-

inally

assembled

at

the

facto

ry. I t is

assumed

that

the

units being installed have bee n thoroughly in-

spected,

cl

ean

ed and reconditioned

and

that

they

conform to

the toleran

ce pecifications recom-

mend ed. General

as

sembly only will be covered,

th

erefore , you should be thoroughly familiar with

the

assembly of t

he

individua l com

ponents

as

out-

lined

in

the

text

of this manual.

CRANKSHAFT

C

oat

the

cra

nkshaft rear hub with

Anti-Seize.

Install

the

two # 16 Woodruff keys

in

the

key slots.

He

at

the

cranksha ft gear

to 200°F

for

one-half

ho

ur and install it on t

he cranks

haft.

Use a

soft

ha

mmer

to bottom the gear

on

the

crankshaft

shoulder. Press the bushings for

the

propeller bolts

in

to

the front cranksh

aft

flange. Refer

to

the

Parts

Lis

t f

or

ava ilable oversize bushings.

CAMSHAFT

C

oat the

rear hub

of

the

camshaft

with

Anti-

Seize. In

sta

ll

the

Woo

druff

key

in

the

key slot.

He

at

the camsha

ft gear

to

200°F f

or

one-half

hour

and press

the gea

r on

the

camshaft.

CRAN KCASE

Atta

ch the engine

mounting

brackets

to

the

t

wo crankcas

e halve

s.

Install

the

main

bearing

shel ls,

camshaft bearing

shells,

and

thrust

washers

in

the cra nk

case

halves.

Check

the

crankshaft

in

bot

h ha lves for end play. See Fig.

46.)

This

clear-

a nce is controlled by

the

thickness

of

the

thrust

washers.

Check

for

clearance

between

the

crank-

sha

ft throws

and

crankcase

walls.

Check

the

cam-

shaft

in

both

open halves

of

the crankcase

for

end

play.

Check

for

clearance

between

the

oil

pump

gea

r on

the

camshaft

and

the

crankcase

walls.

Specified

camshaft end

play

is .006"

to

.010".

Crankshaft

end play

is .008"

to

.020".

FIG.

46.

Cams

haft

and

Crankshaft

Installed

in

Crankcase

1.

Crankshaft with Gear

2.

Cam

shaft

with

Gear

3. Crankcase

FI

G.

47. Torquing Connectin g

Rod

Bol

t

Install the holding

fi xtur

e on

the

crankshaft

front

fla nge. Figure

47

shows a production type

holding

fi

xture

used for engi

ne

build up. Place

the

crankshaft

with

the

propeller flange end down on

the

holding

fixture

base. I nsta ll a

matched

set

of

connecting

rods on

the

crank

shaft,

placing the

machined

surface

on

the

rod bolt boss towards its

adjacent

or

nearest

main be a ring journal on

the

crankshaft.

Oil

the

cran

sha

ft jour

na

ls

prior

to

installing rods.

The

connecting rods

are

numbered

relative

to

their

cylinder position on the

crankshaft

and the

numbe

rs are positioned so

that

they

can

be

read when viewed

throug

h the open top of the

crankca

se.

After

the

connecting

rod bolts have been

torqued

(See Fig. 47 ) ,

check the rod side

clearance

on

the

crankshaft.

Specified clearan

ce

is .008"

to

.014".

Install

the cott

er

pins with their

heads

to-

ward

the

rear

of

the

cran

ksh

aft.

Coa t

the

inside

surfaces

of

the

four

thrust

washers with cup

grease

to

hold

them

in position during assemb

ly

of

the

crankcase.

Oil

the

cranksha

ft

and camshaft bea rings. I n-

stall

the

right

crankcase

half on t

he

cra

nkshaft.

See

that

all

crankcase

seals a re

in

place

as

de-

scribed

in

Section

X.

Insta

ll the camshaft by index-

ing

the

zero

on

the

crankshaft ge

ar with the

zero

mar

ing on

the

camshaft

gear.

(See Fig.

48.)

On

engines having a fuel pump,

in

sta

ll

the

fuel

pump

push rods. In

sta

ll

the

left

crankcase

half

.

Install

the washers

and el

astic stop

nuts

on

the

two

rear

and

two

front

thro

ugh tie- st uds. Draw

the

two

crankcase

sections

toget

her, being sure

that

the

crankcase

seals h

ave

been

properly installed.

Draw

the

two sections tog et

her tig

htly by torquing

the

elastic

stop

nuts

down eve

nl

y. Install the

castle

nuts

on

the

internal

studs

in the

crankcase. Torque

the

nuts

and

install cotter pin

s.

Install

the

three

long t

hrough-bolts

along

the

topside and three

short

through-bolts

at

the

fron t end

of

the case.

Make

sure

that

flat

washers a re und

er

the bolt

heads

as

well as

under

the

elastic

sto

p nu t

s.

Now, recheck

the

camshaft

and cran

kshaft end play.

Check

the

backlash

of the

camshaft

and c

rankshaft

gea

rs

within

the

specified limi ts of .004" to .0 12". Install

the

oil by-pass pla te a nd gask

et

on the lower

left

hand

corner

of

the

case and torq ue the

cap

screws

securing

them with shakeproof washers.

44

FIG.

48.

Timing Gears

1.

Crankshaft

Gear

2.

Camshaft

Gear

PIS

TONS

AND

CYLINDERS

WITH

VALVES

INSTALLED

Install

ri

ngs

on

the

piston

as

follows: First,

slide

th

e oi I control ring down over

the

top

of

the

piston

an

d f

it

it

into

the

bottom

groove; Second,

insert

the s

craper

ring with

the

outside

groove

facing

down

into

the

middle

piston

groove;

Third,

insert

th

e t

op

compression

ring with

the

inside groove

fa ci

ng

up

into

the

top

piston

groove. Install a

set

of pistons,

balanced

within

plus or

minus

1/8

ounce

betwe

en

any

two,

beginning

with

the

front

pistons

and

cylinders

and

working

back

towards

the

rear

of the

engine,

the

# 1

assembly

being

installed

lost. Oil

the

piston

pin

bushing

and

install

the

pi

ston

with

the

piston pin

location

number

on

the

pi

sto

n pin boss

facing

the

front

of

the

engine.

Install the

rear

piston

pin plug. Oil

the

piston rings

and grooves

as

well

as

the

piston

skirt

. Oil

the

in-

side

of

the

cylinder

bore. Install

cylinder

oil seal

ring on

the underside

of

the

cylinder

flange.

Make

sure the ring

gaps

are

staggered

and

using a ring

c

om

pressor, sli

de

the

cylinder

over

the

piston, using

c

orrect

cylind

er

as

numbered

on

the

flange.

When

th

e cylinder skirt

is

just

over

the

bottom

ring, re-

move

the

ring

compressor

and

install

the

front

piston pin plug. Slide

the

cylinder

into

position

on

the

crankc

ase.

Do

not

fully

torque

the

cyl

inder

hold-down

nuts

at

this

time. When

all

the

cylinders

are

insta ll

ed on t

he

crankcase,

temporarily

attach

the intake manifol

ds

wit

hout

gaskets

to

the

intake

ports

on t

he

cy l inders for

the

purpose

of

al igning

the

cy linders while torquing

the

cylinder

hold-down

nuts. Th

is

will as

sur

e a flush

fit

at

the

manifold

to

inlet

port

location,

thus

eliminating

the

possibility

of induction leaks. Remove

the

intake

manifolds.

VALVE

ACTUATING

UNITS

I ns

ta

ll

the

hydraulic

I ifters. I

nstall

the

rubber

packings against

the

bead

on

the

cylinder

head

end

of the lifter

tubes.

Slip

the

tubes

through

the

holes

in

the top

cylin

der

flange

with

the

inside wire

ci rcle

ts

towa rds

the

crankcase

. Install

rubber

pack-

ings

against the bead

on

the

lower end

of the tube.

N

ow

oil the outside di

ameters

of

the

lifter

tube

oil

seals. Using a pi

lote

d driver,

tap the

lifter

tubes

in

to position

so that the outer

end

of

the

tubes

come flush

or

below flush w

ith the

ma c

hin

ed

top

surface

of

cylinders. Be sure low

er pac

king goes

into

hole in

crankcase.

Install t

he lift

er

rods prop-

erly

centere

d in the l

ifter

s.

Install

the

rocker

sup-

port blo

cks

with

the oil holes

in t

he

rocker pins

fa

cing down towa rds the

crankc

ase

and

rocker

a rms

installed

on

the pin. Torque the rocker

sup-

port block nuts

or

cap

screws. Rota

te the cr

ank-

sha ft to el

imina

te

torq

uing the nuts

or

scre

ws

while

the

lifters a re

on

the pea

k of

the

ir re

spec

tive

cam

lobes.

Check

the

side clea rance

of the

roc k

er

arms

to

specified

limits of .00

3"

to

.00

8" (Desired

.006").

Set

the

valve cle a ra n

ce

to .040".

Insert

.040"

feeler stock

between t

he

valve

tip

and rocker

arm

with

piston on top

center

of

its compression

stroke

and

the

rocker

arm fully depressed

aga inst

the

spring

tension

of

the

volve lift

er.

Turn the

rocker

arm

adjustment

screw

unt

il the feel

er

is

a

light

drag

fit. (See Fig.

49.

) Tig

hten

the ja m nut

to

hold

the

scre

w in position. Recheck

.04

0" clear-

ance

after

the

nut

is

tightened.

FIG.

49.

Checking Valve Clearance

TIMING

GEAR CASES AND ACCESSORY

DRIVE GEARS

Trim

the

crankcase oil

seal

rubbe

r pa ckings

flush with

the

crankca

se s

urfa

ces. Insta

ll

the

front

timing

gear

case

with

the

specified gasket

between

the

crankcase

and

the

timing gea r

cas

e surfa ces,

making

sure

the

two

alignment

dowe

ls loca

ted in

the

crankcase

Ilne up with

the

holes provid ed in

the

timing

gear case

. Pull

the

ti ming

gear case

down

tight

against the

crankc

ase by

torquing the

eight

internal

5/ 16"-1 8 x 7/

8"

hex hea

d ca p screws

down evenly. (See Fig.

50

-5.) Use

plain 5/1

6" flat

washers

and

secure

with lac i

ng

wire.

At

the

sam

e

time

install a

nd

torq

ue

the

two 5/ 16"- 18 x 2-1/ 4 "

45

FIG.

50.

Starter

and

Accessory Drive G

ar

A.sseMbly

1.

Starter

Gear

and

Hub

5.

Front Timing

Gear

2. Accessory Drive

Gear

Housing

to

Crankcase

Cop Screws

3.

Tachometer

Dnve

Gear

4. Front Timing

Gear

Housing

cap

screws with

shakeproof

washers holding

the

bottom

of

the

timing

case

to

the

crankcase

.

The

starter

gear

is

then

heated

to

2000 to

2500 F

and

dnven

onto

the

rear

end

of

the

crankshaft

until inside

hub

of

the

gear

bottoms

on

the

crank-

shaft

gear. (See Fig. 50-1.)

The

special

tab

washer

and

crankshaft

nut

are

then

installed

to

hold

the

gear

in

position. A proper

spanner

wrench should

be used

to

tighten

the

nut.

Rap

the

wrench

handle

several times with a

hammer

to

make

sure

the

nut

is

down tight.

Wedge

the

washer

material

into

the

slots

in

the

nut

to

prevent

the

nut

from loosening.

The accessory or

magneto

drive

gear

is

then

in-

stalled

in

the

rear

end

of

the

crankshaft,

making

sure

that

the

slotted keyways

in

the

gear

hub

fit

over

the

keys

in

the

crankshaft.

The

inside

gear

face

should

bottom

on

the

end

of

the

crankshaft

and a soft

metal

driver

and

hammer

may

be

used

for this purpose. On both

gear

installations,

the

contact

surfaces

should

be

coated

with

Anti-Seize

Compound.

The

rear

timing

gear

case

is

aligned

with

the

front

timing

gear

case

by

means

of

a pilot

tennon

on

the

rear

case

fitting

into

the

front case.

Make

sure

the

specified

gasket

is

aligned

correctly be-

tween the

contact

surfaces

of

the

two cases.

The

ten

1/

4"-20

x 5/

8"

hex

head

cap

screws holding

the

two

cases

together

are

then

torqued

down

evenly.

At

the

same

time,

the

two 3/ 8"-16 x 1"

hex

head

cap

screws on

either

side

of

the

case

are

torqued.

Shakeproof

washers

are

used

throughout.

On some

engine

models,

the

pilot

tennan

is

omitted

and

the

two

cases

are

al igned by

means

of

two

special hollow dowels on

either

side

of

the

case.

Two special

heat-treated

1/ 4"-28 x

I"

through

bolts

machined

to

.2495"

to

.2505"

diameter

with

flat

washers

and

elastic

stop

nuts

are

installed

through

the

dowel holes.

OIL PUMP AND FLOTO UNIT

Install

the

oil

pump

with

the

inlet

tube

and

Floto

unit

attached

. (See Fig. 51.

The

pump

cover

with

attached

inlet

tube

and

the

pump

body

en-

closing

the

pump

gears

are

secured

to

the

oil

pump

pad

on

the

bottom

side of

the

front

left

half

of

the

crankcase

by four

1/4"-20 x 2-3/4"

hex

head

cap

screws

and

plain 1 /

4"

flat

washers. 0'1

the

model

6A4-165-B3,

one

of

the

four

1/4"-20

cap

screws

is

only 2-1 / 2" long. This screw goes

in

the

boss

nearest

the

cam

lobe

to

provide

cam

lobe

clearance.

A

cotter

pin

and

special wire clip hold

the

Floto

unit

to the

end

of

the

Inlet tube. I nstall

the

bracket

and

clamp

about

the

inlet

tube

to

support

the

outer

end

of

the

tube,

as

well

as

the

weight

of

the

Floto

unit.

The

bracket

mounting

screws

and

clamp

tight-

ening screw

are

drawn

up

tight

and

secured with

lacing wire.

Check

the

Floto

unit

for free travel.

Also

check

the

distance

of

Floto in its lowest posi-

tion from

the

bottom

of

the

crankcase.

This

measurement

must be less

than

the

depth

of

the

oil

pan

to

prevent

interference

between

the

bottom

of

the

pan

and

the

Floto unit.

FIG.

51.

Oil Floto

Installation

1. Oil

Pump

4. Oil

Inlet

Pipe Suppo

rt

Brocket

2.

Oil Inlet Pipe

5.

Oil

Inlet

Pipe

Clamp

to

Bracket

3.

Floto Unit

46

OIL PAN

Install

the

speciHed

gasket

between

the

oil

pan

and

the

crankcase.

Install

the

solid

aluminum

re-

inforcement

bond

under

the

oil

pan

mounting

flange

Draw the

pan

up

to

the

crankcase

by evenly

torquing

the

twenty-four

5/16"

-18 x 3/

4"

fillister

head

screws.

The

ad cooler

brackets

at

either

side

of

the

pon should be installed

under

the

three

speci-

fied

cap

screws.

The

two

outside

nuts

holding

the

rear

of

the

pan

to

the

timing

gear

case

may

then

be torqued.

Shakeproof

washers

are

used

through-

out.

Some

engines

will

be

equipped

with

cost

all

pans

and

no

reinforcement

band

is

needed

. Leave

the

middle

stud

on

the

bottom

rear

of

the

crank-

case

free

for

installation

of

the

distributing

zone.

CRANKCASE COVER

AND

VALVE COVERS

The

top

crankcase

cover

is

secured

to

the

top

crankcase

surface

by

means

of

sixteen

5/16"-18

x 5/ Sn hex

head

cap

screws. (See Fig.

52.)

The

cap

screws

are

torqued

and

shakeproof

washers

are

used. A specified

gasket

is

used

between

th~

two

matching

surfaces.

Before Installing

the

crankcase

cover,

the

raised

bead

around

the

inside

of

the

cover

mounting

flange

should

be

inspected

to

see

that

it

is

undamaged.

Before installing

the

valve covers,

make

the

fol-

lowing inspection. Examine

the

top

surface

of

the

cylinder

for nicks

or

scratches.

Examine

the

raised

bead

of

the

valve cover

mounting

flanges

for

dents

or

warpage.

Place

the

valve cover on

the

cylinder

head

without

the

gasket

and

check

for

contact

with

.

003"

feeler

gauge.

Use a

specified

gasket

which

is

in

good condition. Draw

the

cover down evenly

by

tightening

the

screws in a criss-cross fashion, a

few

turns

at

a time.

This

procedure

is

most

im-

portant

to

prevent

warpage

and/ or

bending

of

the

cover.

FIG.

52.

Crankcase

Cover

1.

Crankcase

Cover

3.

Crankcase

Cover

Gasket

2.

Attaching

Screw

and

4. Oil Filler Cop

Shakeproof

Washer

INDUCTION SYSTEM

I nstall

the

ihlet

manifolds, observing

that

all

screw plugs

are

installed

and

tight

and

that

the

manifolds

and

gaskets

fit flush

to

the

inlet

ports

on

the

cylinder.

Tighten

down evenly

the

six Allen

head

5/

16"-

18

xl"

screws holding

each

manifold

to

the

cylinders. Use

plain

5/16"

flat

washers

and

secure

the

screws with lacing wire .

Later

engine

models use

slotted

hex

head

cap

screws

and

shake-

proof

washers

for

attaching

the

manifolds.

Install

the

front

equalizer

pipe

assembly

com-

plete

with

the

connecting

hose

and

support

ing

bracket

holding

this

assembly

to

the

crankcase.

Attach

the

distributing

zone

to

the

timing

gear

case

by

means

of

two 1/

4"

20

x 2-1/

2"

hex

head

cap

screws,

as

well

as

by

the

center

stud

at

the

rear

end

of

the

crankcase

through

the

oil

pan

flange.

Torque

the

cap

screws

and

use

shakeproof

washers.

Now install

the

rear

connectmg

pipes

between

the

zone

and

the

manifolds.

IMPORTANT-

In

assembling

the

induction

system,

extreme

care

must

be

exerted

to

see

that

all

gaskets

and

packings

are

properly installed

so

as

to

eliminate

induction

leaks.

Do

not

reuse worn

or

mutilated

gaskets

and/ or

rubber

packings. Use

specified

parts

only.

ACCESSOR I

ES

STARTER: Install

the

starter

on

the

studs

at

the

top

pad

of

the

rear

timing

case

using two 3/

8"-24

elastic

stop

nuts

or

flat

washers, 3/

8"

plain

nuts

and

palnuts.

The

cover having

the

breather

tube

ottachment

may

then

be

installed,

complete

with

a

gasketJ on

the

front

side

of

the

timing

case.

Torque

the

two

1/4"-20

x

1/2"

hex

head

cap

screws

and

use

shakeproof

washers.

FUEL PUMP: Engine models haVing a fuel

pump

carry

a special

right

rear

mounting

bracket,

having

a

pad

far

the

pump. Check

to

see

that

the

end

of

the

pump

actuating

push

rod

extends

.292"

to

.311" beyond

the

fuel

pump

pad

gasket

. Install

the

pump

on

this

pod

and

pull

the

two

5/16"

through

bolts

up

tightly. Be

sure

the

gasket

between

the

pump

and

the

pad

is

of

the

specified

type

and

is

installed

properly.

Inasmuch

as

fuel leaks

cannot

be

tolerated,

it is

best

to

use a new

gasket

whenever

assembling

this

unit

to

the

engine. The

pump

inlet

and

outlet

are

marked

"in"

and

"out".

Hook

the

lIin

ll

side

of

the

pump

to

the

fuel supply

tank

and

the

"out"

side

of

the

pump

to

the

carburetor

supply

line.

IGNITION SYSTEM: Install

specified

14

mm.

spark

plugs using a

13/16"

deep

socket

and

torquing

to

180

to

240 in. Ibs.

Be

sure

that

copper

gaskets

are

installed

under

each

plug. Install

mag-

netos

as

outlined

in

the

magneto

installation

sec-

tion

of

thiS

manual

on

page

39.

Secure

magnetos

with special

flat

washers,

plain

nuts,

and

palnuts.

Connect

all Ignition wires

between

magnetos

and

plugs

as

shown

in

Figs.

32

and 33.

Carefully

inspect

all ignition Wires for

any

breaks

in

the

wire

insulation.

GENERATOR : Install

the

generator

on

the

bot-

tom

pod

of

the

rear

timing

case.

Use

either

flat

washers,

plain]

/4"

nuts

and

palnuts,

or

elastic

stop

nuts

on

four

1/4"-28

studs

to

attach

the

generator

to

the

engine.

CARBURETOR: I nstall

the

carburetor

over

four

1/4"-20

studs

on

the

bottom

of

the

dlstributing

zone. Use

1/4"-28

elastiC

stopnuts

to

secure

the

carburetor

to

the

zone.

The

model

6A4-165-B3

engines

use

5/16"-24

studs

and

elastiC

stop

nuts.

OIl. COOLER

The

oil cooler

is

ottached

to

the

engine

just

below

the

oi I pan

and

is

suspended

from two

brackets

which

are

supported

by

three

oil

pan

hold-

47

ing

cap

screws

on

eithe r sid e

of the engin

e. B

efore

the actual installa ti on

of the H

eat Exc

han

ger oil

cooler, t

he

small b

rac

ke ts s

upporting

the

rubber

bu

mpers which act as shock

absorbers

aga

inst

the

o

il

pa n a re Iin

ed

up

by slipping t

he 1/4"-28 x 5/

8"

cap scre

ws through the cooler a

ttachme

nt holes,

then

through the bumper bra c

ket

holes, a nd

finally

throu

gh

the

holes in the bracke

ts

on t

he

engine.

Use

1/

4"

plain

flat wa

sher

s a nd

elastic stop

nuts

with

the

heads

of the ca p

scre

ws

being towa rds

the

engine

oil

pan.

Whe

n assembly

is

complete, t

he

two

ru

bber bumpers

sho

uld be crush

ed

slightl y aga in

st

ei

ther

side

of the

engine o

il pan. So

me

engine

mo

dels have Fe

dde

rs o

il

coolers, which w

ill incor

-

por

ate the

rubb

er b

ump

ers d irectly

on

the

engine

o

il

cooler s

upp

ort

ing br

acke

ts and the necessity

f

or

an

individual brac

ket

to

hold

the rubb

er bumper

is

eliminated

. T

he

"T" sha

ped

connection havi ng

the

adapter for

the

oi I temper

atu

re bulb

is

the

"oil-out-of-cooler" fitt

ing. This pipe

is

conne

cted

to

the

"oil -

into-engine"

or

fro

nt

fittin

g on t he oil

by-p

as

s pla te. T

he pipe

elbow nea r t

he

bottom of

the cool

er

is

the "oil-into-cooler" fi

tti

hg a nd shou ld

be

con

nected

directly

to

the

"oil

-ou t -of

-engine"

or

re

ar

fitting

on

the

oil by-pass

plate

. Special for

med

tubing

and

compos

iti

on

hoses

wit h hose clamps

a re

used

for

the

oil cooler hook-up.

Th

e e

ngine

is

now

read

y for

inst

a lla tion on

the

test

block

or

in

the

air

craft,

depen

di ng on t

he

ex-

tent

of

the overhaul made.

Disassem

bly for over

haul can

be

conv

eniently

accomplished by

performi

ng the above

procedur

e

in rever se.

Cl

earances

and to

rque

limits a re list

ed

on

page

.--------12.

_______

of

this ma nual.

X

XVII

- ENGINE

ESTING

T

he

proc

edure

outlined

is

intended

to

serve

as

a

guide

for

testing

the

engine after it

has

been

over

-

ha

uled.

FACTORY RUN -IN SCHEDULE

Model 6A

4 -

1S0-B3 & B3

1 Model

6A4-16

S-B3

RPM

Durat

ion RPM

Duration

1400

30 min.

1

40

0

15 min.

1

60

0 30 min.

16

00

15

min

.

18

00

30

min

.

1800

30

min.

200

0

30

min

.

2000

30

min.

22

00

30

min

.

2200

30 min.

2400

30

min

.

2500

30 min.

26

00 30

min

.

2600

30 m in.

2650-27

50

30

min

.

2750

30

min

.

28

50 -

2950

30

mi

n.

4.00

hrs.

Total

4

.00 hrs. Total

Check acceleration

.

Check

ma gneto

at

full t

hro

tt le.

Maxi

mum

drop

200

RP

M.

Ch

eck mixture contro

l.

Check

idle

speed.

Shut

down wit h idle

cut

-off.

48