MG MGA Twin Cam Manuel d'instructions

Series

MGA

Twin

Cam

WORKSHOP

MANUAL

NOTE

Refer to the end

of

the appropriate Section for the latest instructions when

carrying out work on the vehicle.

Additional copies

of

this publication (Part No. AKD926B) can only

be

obtained from an M.G. Distributor.

Issued by

THE

M.G.

CAR

COMPANY

LIMITED

Propri•tor.: Morris Motors Limited

ABINGDON

-ON

-THAMES

Exported by

NUFFIELD

EXPORTS

LIMITED

Propri•tors: Morris Motors Limited

COWLEY,

OXFORD,

ENGLAND

MGA (Twin Cam). Issue

3.

32403

INTRODUCTION

This Manual has been prepared to provide the service operator with the necessary

information for the maintenance and repair

of

the M.G. (Series

MGA

Twin Cam).

The Manual also serves as a ready-reference book for service supervision and covers

items

of

procedure for the guidance

of

both the fully qualified and the less-experienced

mechanic.

UNIT ARRANGEMENT

In the Manual the complete vehicle

is

divided into Sections each

of

which deals with

an assembly or major component and carries a reference letter.

NUMBERING

OF

~kGES

AND ILLUSTRATIONS

The pages and 1llustrations are numbered consecutively within each Section, and the

Section title and letter are shown at the top

of

each page.

SERVICE TOOLS

Use

of

the correct tools contributes to

an

efficient, economic, and profitable repair.

References have therefore been made

to

such tools throughout the Manual.

MGA (Twin Cam).

Issue

3.

32403

CONTENTS

Section

General

Data

Engjne A

Ignition Equipment B

Cooling System c

Fuel System D

Clutch E

Gearbox F

Propeller Shaft G

Rear Axle H

Rear

Road

Springs I

Steering Gear J

Front Suspension K

Hydraulic Dampers L

Braking System M

Electrical Equipment N

Wheels, Tyres, and Jacking 0

Lubrication p

Chassis R

Body

..

s

MGA

(Twin Cam). Issue

3.

32403

3

r--

J

i I

I !

i l

i

I l

! I

I

I I

l

i

~

I

.

~

I

~

i

< i

!

~

i

i 00

i I

I 0

l

~

f

i

~

!

-

e !

~

i

u I

.51

i

~

!

~

i

< i

C-'

::;;

riJ

~

·-

...

~

00

-

.

C-'

:i

~

:I:

~

4 MGA

(Twin

Cam)

. Issue

3.

32403

I

l

I

i

I

THE M.G. (Series MGA

Twin

Cam)

ENGINE

MGA (Twin Cam). Issue

1.

32403

I

j

;

j

!

I

i

I

i

j

I

i

I

:

i

!

~

I

i

I

l

.......

._....~

5

GENERAL

DATA

t:NGINE

Type

Number

of

cylinders

Bore

Stroke

Capacity

Firing order

Compression ratio

Capacity

of

combustion chamber (val

ves

fitted)

Valve

operation

B.M.E.P

...

Torque

Cooling system

Oversize

bore:

First

Maximum

CRANKSHAFI'

Main journal diameter

Crankpin journal diameter

Main

bearlnp

Number and type

Material (bottom half)

Material (top half)

Length

..

End-clearance

..

End-thrust

Running clearance

CONNECTING RODS

Length between centres

..

Big~ad

bearl~~p

Material (bottom half)

Material (top half)

Bearing side-clearance

Bearing diametrical

cl

earance

PISTONS

Type

Material

Clearances:

Bottom

of

skirt

Top of skirt

Type

Materi

al

Clearances:

Bottom

of

skirt

Top of skirt

PI

STON RINGS

Compression:

Top ring

Second and third rings

MGA

(Tw

in Cam).

Issue

4.

3

2403

BCI6GB.

4.

. . 2·969 in.

(75-41

mm.).

. . 3·5 in.

(89

mm.).

. .

96·906

cu. in.

(1588

c.c.).

I,

3,

4,

2.

9·9 : l with pistons AEH681.

8·3 : I with pistons

AEH690.

. .

86·6

c.c.

(5·28

cu. in.).

. . Twin overhead camshafts.

163

lb.Jsq. in.

(I

1-4

6

lcg

./cm.1)

at

4,500 r.p.m.

lOS

lb.

ft

. (14·5

kg.

m.)

at

4,500 r.p.m.

Thermo-siphon, pump- and fan-assisted.

. . -()JOin.

(·25

4

mm

.).

..

-040

in.

(Hll6

mm

.).

. . 2 in. (50-8

ro

m.).

1·8759

to

1·8764

in

.

(47-65

to

47-66

mm.).

. .

3.

Shell type.

. . Steel-backed, lead-indium· or lead-tin-plated.

. . Steel-backed, lead-ind

iu

m-

or

lead-tin-plated.

I Sia. (38 I

mus

.). (error) 1.

25

in.

(31.

75

mm)

·006

in. max. (·

152

mm

.).

.. Taken by tbrust washers

at

centre maio bearing.

-(}()2

to

·0037

in.

(.051

to

·094

rom.).

6·5 in.

(165-1

mm

.).

Steel-backed, lead-indium- or lead-tin-plated.

. . Steel-backed, lead-indium- or lead-tin-plated.

. .

·008

to

·012

in.

(·203

to

·305

mm.).

·002

to

·0037

in.

(·OS

I

to

·09

4 mm.).

. . Flat

top

(9·9

: I compression ratio).

. . Aluminium alloy.

. . ·

0035

to

-(}()66

in.

('

090

to

·

168

mm.).

. .

-(}()58

to

·0083

in

.

(·

14

7

to

·211

mm.).

Domed top (8·3 : I compression ratio).

. . Aluminium alloy.

·0035

to

·

0041

in. (·

090

to ·

101

mm.).

·0070

to

·0076

in. (·

177

to ·192 mm.).

. . Plain.

. . Tapered.

General Data I

GENERAL

DATA-continued

Width

..

Th

ickness

Fitted

gap

Clearance in

groov

e . .

Oil c

ontrol

type

..

(Fr

om Engine

No.

44

6)

Wi

dth

. .

Thickness

Fitted

gap

Clearance in

groove

GUDGEON

Type

Fit

..

Dia

met

er

VALVES

AND

VALVE

GEAR

Valves

Seat angle:

Inlet

..

Exhaust

H

ead

diamete

r:

Inlet

• .

Exhaust

Stem

diamete

r:

Inlet ••

Exhaust

Valve lift

Valve stem

to

guid

e clearance:

Inlet . .

Exhaust

Valve clearance

Chain

pitch

and

number

of pitches ••

Inlet valve:

Opens

Closes

Exhaust

valve:

Opens

Closes

VALVE

GUIDES

Length:

Inl

et

Exhaust

..

Di

amet

er:

Inlet:

Outs

ide

Ins

ide

Exhaust: Outside

Insi

de

Fitted height above

head:

Inl

et

Exhaust •.

General Data 2

. . ·0

54

to

·055

in.

(1

·

37

to I·

39

mm.).

. . ·

124

to

·131

in. (3-15

to

3·

33

mm

.).

.. ·

008

to ·013 in. (·20 to ·33 mm.).

. . ·0015

to

·0035

in

. (·038

to

·089 mm.).

. .

Microland

sc

raper

.

. . Twin-segment scraper.

. . ·1

552

to

·

1562

in.

(3

·

94

to

3

·9

9

mm

.).

. . ·1

24

to

·131 in. (3·

15

to 3

·33

mm.).

. . ·008

to

·013 in. (·20

to

·33

mm.).

. .

·001

5

to

·00

35

in. (·038 to ·089

mm.).

. . Fully floating.

Hand

-

push

fit

at

room

temperature.

·

875

in. (22

·22

mm.).

. .

1·59

in. (40·38 mm.).

1·

44

in. (36·58

rom

.).

•

342

in. (8·68 mm.).

·3

42

in. (8·68

mm

.).

·375

in

. (9·52 mm.).

. . ·00155 to ·00255

in.

(·0394 to ·0635

mm

.).

·00

155

to

·00255

in

. (·0394 to ·0635

mm.

).

·

01

4

to

·01

5 i

n.

(·356 to ·381

mm.)

(cold).

·3

75

in.

(9

·

52

mm.),

132

pitches.

20° B.T.

D.C

.

50°

A.B.D.C.

50°

B.B.D.C.

20°

A.T.D.C.

2-/r

in. (52·39

mm.

).

2-if in.

(61

·

91

mm.).

·5645

to

·

5655

in. (14·33

to

14

·36 mm.).

·3

438

to

·3

443

in.

(8

·73

to

8·74

mm

.).

·

5645

to

·5655 in. (14·33

to

14·

36

mm.).

·

343

8

to

·

3443

in.

(8

·

73

to

8·7

4

mm.).

·750 in. (

19-()5

mm.).

·

844

in. (21·43 mm.).

MGA (Twin Cam). Issue 4.

32403

GENERAL

DATA-continued

VALVE

SPRINGS

Free

length:

Inner

Outer

Fitted

length:

Inner

Outer

Number

of

working

coil

s:

Inner

Outer

Pressure:

Valve

open

Valve closed

TAPPETS

Type

Diameter:

Body

Working

face

Length

(From

Engine

No.

1087)

CAMSHAFIS

Journal

diameters

End-float

. .

Bearings:

number

and

type

Inside

diameter

..

Clearance

..

HALF-SPEED SHAFT

Journal

diameter

s:

Front

Centre

Rear

End-float . .

Bearings:

number

and

type

Inside

diameter

(reamed

in

position

):

Front

Centre

. .

Rear

Clearance . .

ENGINE

LUBRICATION

SYSTEM

Oil

pump

Type

Relief pressure valve

operate

s

Relief valve s

pring:

Fr

ee length

..

Fitt

ed le

ngth

Oil filter

Type

C

ap

a

cit

y

M

GA

(T

win

Cam). [

$SU

e

6.

32

403

2·3

in

. (58·42 rom.

).

2·54 in. (64·51

mm.).

. . 1·62

in

. (41-15 mm.).

1·78 in. (45·

21

mm

.

).

7·8.

6.

. .

Inner

65

lb. (29·5 kg.).

Outer

125 lb. (56·7

kg

.

).

. .

Inner

42

lb

. (19·1

kg

.).

Outer

84

lb.

(38·1

kg

.

).

. .

Inv

erte

d

bu

ck

et.

1·5 in. (38·1 mm.).

1·5 in. (38·1

mm

.).

. . 1

·2

5 in.

(31

·75

mm

.

).

. . 1·5

in

. (38·1 mm.).

1·

250

to

1·2505 in. (31·75 to

31

·76 mro.)

·001

to

·005 in. (·025 to ·127

mm

.

).

..

3.

D2

bi

-

metal

bearings.

. . 1·2515

to

1

·2

525

in.

(31·788

to

31-813 rom.).

. . ·001

to

-()()25

in. (·0254

to

·0635 mm.).

1·78875

to

1·78925

in

. (45·43

to

45·44

mm

.

).

1·

7287

5 to

1·72925

in

.

(4

3·

91

to

43·92

mm

.

).

1-62275

to

1·62325 in. (41·22

to

41·23

mm

.

).

·003

to

·

006

in

.

(·0

76

to

·

152

rom.).

. . 3. ThinwaU steel-backed white

metal

1·

7

90

in

. (45·47

mm

.).

1·730

in.

(4

3·94

mm.)

.

. . 1·624 in. (41·25

mm

.).

. .

-()01

to

·002 in. (·025

to

·051 mm.).

. . Eccentric

rotor.

. . 50 lb.fsq.

in

. (

3·

52 kg.f

cm

.2) .

. . 3 in. (76·2

mm

.).

..

2

1~

in

. (54·77 mm.)

at

16

lb. (7·26

kg

.)

load

.

. . External renewable elcmc:nt,

fuU

-fiow.

.. i pint (·6

U.

S.

pint

, ·28

litr

e)

.

General D

at

a 3

Oil

pr~ssure

Idling

Runn

ing

GENERAL

TORQUE WRENCH

SEITINGS

Cylinder head

nuts

Main

bearing

outs

Big-end

bearing

nut

s

Clutch assembly

to

flywheel

Camshaft

bearing

nut

Steering-wheel

nut

FUEL

SYSTEM

Carburettcr

Make

and

type

Diameter

Needle

..

J

et

Pi

sto

n

spring

..

AIR CLEANER

Make

and

type

FUEL

PUMP

Make

and

type:

Delivery test

Suction lift

Output

lift

COOUNG

SYSTEM

Type

Thermostat

setting

Quantity

of

anti-freeze:

15

° f

ro

st

25° frost

35° frost

IGNITION

SYSTEM

Sparking plugs

Size

Plug

gap

..

Coil

Distributor

contact

points gap

Suppressors

Static t

im

ing

:

9·1

: I compression

ra

tio

8·3 : 1 co

mpres

s

ion

ratio

CLUTCH

Make

and

type

Diam

eter

..

Facing material

General

Data

4

DATA

-

contin

u

ed

10

to

IS

lb.fsq. in. (·7

to

1·05 kg

.f

cm.

1

).

SO

to

60 lb./sq. in. (3·52 to 4·22 kg.fcm.1) .

. . 70

lb

. ft. (9·68

kg

. m.).

. . 70

lb

. ft. (9·68 kg. m.).

50

lb.

ft

. (6·913

kg

. m.).

. . 35

to

40

lb. ft. (4·84

to

5·53 kg.

iO

.).

33

lb. ft. (4·56 kg. m.).

. . 42 lb. ft. (5·15 kg. m.).

. .

S.

U. twin

H6

semi-downdraught.

It

in. (44·45 mm.).

. .

OA6

(standard).

RH

(rich).

OA7

(weak).

. . ·10 in. (2·54 mm.).

Red,

4i

oz. (128

gm.

).

Vokes,-oil-wetted.

S.U.

electric, large capacity.

12

·5 gal.fhr. (54·28 litresfhr.).

33 in. (83·8 em.).

48 in. (121·9 em.).

. . Pressurized

rad

ia

tor.

Thermo-siphon,

pump-

and

fan-assisted.

. . 50

to

55° C. (122

to

131° F.).

It

pints (

1-8

U.S. pints, ·85 litre).

. . 2 pints (2·4 U.S. pints, 1·14 litres).

.. 3i pints (4·2 U.S. pints, 2 1itres).

Champion

N3.

Champion

N58R

(for competition

work

and

other

arduous

conditions).

14

mm.

·025 in. (·64 mm.).

Lu

cas

HAI2.

Lucas, type

DM2

.P4.

·014

to

·016 in. (·35

to

·40

mm.)

.

Lucas No. 78106A fitted

on

each

H.T.

cable.

T.D.C.

8°

B.T

.

D.C.

Borg

& Beck

8ARG.

Single dry plate.

8 in. (20·3

em

.).

Wound

yam,

reinforced.

MGA (Twin Cam). Issue 6. 32403

GENERAL

DATA-continued

Pressure springs

..

Colour

..

Damper springs

Colour

..

Release lever ratios

GEARBOX

Number

of

forward speeds

Synchromesh

Ratio

s:

Top

Third

Second

..

First

Reverse

Overall ratios:

Top

'l'tird

Second

..

First

Reverse

Speedometer gea

rs

ratio

..

STEERING

Type

Steering wheel

turns-lock

to lock

Steering wheel diameter

..

Camber angle

Castor angle

King pin inclination

Toe-in

Track:

Front

Rear

FRONT SUSPENSION

Type

Spring detail:

Coil diameter (mean)

Diameter

of

wire

Free height

Number of free coils

Static laden length

at

load

of

Dampers

..

Damper settin

g!O:

Rebound:

Bl

ow-off

Time setting

Compression:

Bl

ow

-o

ff

Time setting . .

MGA (Twin Cam). Issue

3.

27765

6.

Light grey.

6.

Maroon

and

light green.

11·7:

1.

4.

Second, third,

and

fourth gears.

Standard Close ratio

gearbox gearbox

1

·0

:

1.

I·0 :

I.

1·374 :

1.

. . 2·214 : I.

..

3·64 :

I.

4·67 :

I.

4·3 :

I.

. . 5·908 :

l.

9·520 :

I.

15·652 :

1.

. .

20

·4

68

: I.

5/

12

.

. . Rack and pinion.

2j.

16! in. (419·10 mm.).

1·

267:1.

1·62 :

I.

2·

44

5:

I.

3·

199

:

I.

4·3 :

I.

5

·

44~

:

I.

6·9

66:

I.

10·52 :

I.

1

3·75:

1.

1° positive to

lo

negative

on

full bump.

4

o.

. . 9° to

tot

0

on

full bump.

Wheels parallel.

47ft

in. (1·217 m.).

. . 48! in.

(1

·242 m.).

. . Independent coil.

. . 3·28 in. (82·25 mm.).

. . ·54 in. (13·72 mm.).

. . 9·09 in. ±

nin.

(23·09

cm

.±

l·6 mm.).

..

7·2.

. . 6·6 in. (16·76 em.).

1,

19

3

lb

.

(5

41

kg.).

. . Piston type.

1,

150

lb. in. (13·3 kg. m.) at

18<'

0/sec.

at

18

° C.

72

5

lb

. in. (8·3 kg. m.)

at

20°/Sec.

at

18

° C.

55

0

lb

. in. (6·3 kg. m.)

at

1

80

°/Sec.

at

18°

C.

. . 3

50

lb

. in. (4·0 kg. m.)

at

20°/

Sec.

at

18

° C.

General D

ata

5

MG MGA Twin Cam Manuel d'instructions

Manuels Automobile populaires d'autres marques