MG MGB Instruction manual

MW
Workshop Manual
Publication Part No. AKD 3259 (14th Edition)
@
Leyland Cars—service
Cowley, Oxford OX4 2PG, England

MGB.
Introduction
Maintenance
Lubrication Chart
General Data
Engine Tuning Data
Engine
Engine (Local and territorial requirements) ..
Ignition System
Cooling System
Fuel System
Fuel System (Evaporative Loss) ..
Clutch
Gearbox ..
Overdrive
Gearbox (All Synchromesh)
Overdrive (Type L.H )
Automatic Gearbox ..
Propeller Shaft ,
Rear Axle and Rear Suspension (Three-quarter-■oating Type) ..
Rear Axle and Rear Suspension (Semi-■oating Type)
Steering Gear ..
Steering Gear (Energy Absorbing Column)
Front Suspension
Hydraulic Dampers ..
Braking System
Braking System (Tandem Master Cylinder)
Electrical System
Electrical System (Local and Territorial Requirements) ..
Wiring Diagrams
Wheels and Tyres
Body
Body (Local and Territorial Requirements) ..
Service Tools ..
Recommended Lubricants ..
Issue 3. 86842
CONTENTS
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MAINTENANCE SUMMARY
R.H.D. and L.H.D. except North America—continued
ACTION
OPERATION X
E: 8
on n
Re■tengine drain plug
Re■tgearbox drain plug
Re■tgearbox drain plug (every 24,000 miles)
Paint timing marks (early models)
Lower lift
Fit exhaust extractor pipe
Renew engine oil ■lter
Check/ top up gearbox oil
Fill gearbox with oil
Fill gearbox with oil (every 24,000 miles)
Check/adjust torque of cylinder head nuts
Check/adjust torque of rocker shaft nuts
Check/adjust torque of manifold nuts
Check/ adjust valve clearances
Fill engine with oil
XCheck/ top up engine oil
Lubricate water pump (early models only)
Lubricate dynamo bearing (early models only)
Top up carburetter piston dampers
Lubricate accelerator control, linkage and pedal pivot
Renew air cleaner elements
Check security of accessible engine mountings
Check driving belts, adjust or renew
Clean/adjust spark plugs
Renew spark plugs
Clean and test crankcase breather valve
Check/ top up clutch ■uid reservoir
Check/ top up brake ■uid reservoir
Check/ top up windscreen washer reservoir
Check/top up cooling system
Renew fuel line filter
Clean brake servo ■lter
Check cooling and heater systems for leaks
Run engine and check sealing of ■lter, stop engine
Rechec‘k/ top up engine oil
Connect instruments and check data
Check/adjust distributor points, renew if necessary
Check volt drop between coil CB and earth
Lubricate distributor
Run engine
Disconnect vacuum pipe, check dwell angle, adjust points as
necessary Using electronic
Check stroboscopic ignition timing equipment
Check distributor automatic advance
Check advance increase as vacuum pipe is reconnected
Check throttle operation, check/adjust carburetter idle speed
and mixture settings
Check/ top up automatic gearbox ■uid
Stop engine
0Remove wing covers
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~Maintenance 2" MGB. Issue2. 86842

MAINTENANCE SUMMARY
R.H.D. and L.H.D. except North America—continued
After
Sales
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ACTION
U!
OPERATION x
Oxxxx .0 Ox
x.
X
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Lubricate all locks and hinges (not steering lock)
Fill in details and fix appropriate Unipart underbonnet stickers
Close bonnet
Check and if necessary renew windscreen wiper blades
Remove exhaust extractor pipe
Remove spare wheel
Check spare tyre complies with manufacturer’s speci■cation
Check depth of tread
Check visually for external cuts in tyre fabric
Check visually for external exposure of ply or cord
Check visually for external lumps or bulges
Check/adjust tyre pressure
Check fuel filler pipe connections
Refit spare wheel. Drive car off lift. Remove rear compartment floor covering and
access panel
Check/ top up battery electrolyte
Clean and grease battery connections
Re■trear compartment floor covering and access panel
Check/ adjust headlamp alignment
Check/ adjust front wheel alignment
Carry out road or roller test and check function of all instrumentation
Report and additional work required
Ensure cleanliness of controls, door handles, steering wheel, etc
Oxxxxxxx00x00x O><><><><><><><O x.
X
X.
X
X
xxxxxOxx
This Maintenance Summary was produced from Leycare Supplementary Job Sheet AKD 8469 (1st Edition). Job sheets used
by British Leyland Distributors and Dealers operating Leycare Service are updated as modi■cations affecting routine
maintenance are introduced and the content of this maintenance summary may differ from that currently used by Leycare
Service operatives.
MGB. Issue2.
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Service 3‘
86842 Maintenance 3

MAINTENANCE SUMMARY
NORTH AMERICA
The following items should be checked weekly by the driver:
Engine oil level
Brake ■uid level
Battery electrolyte level
Radiator coolant level
Windshield washer reservoir level
All tyre pressures
All lights for operation
Horn operation
Windshield wipers operation
MAINTENANCE INTERVALS
TThese items are emission related
Carry out the services indicated by Xin column
The Lubrication Service at 3,000-mile or 3-month intervals Lubrication
Aat 6,000—mile or 6-month intervals Service AB
Bat 12,000-mile or 12-month intervals
*Speci■ed otherwise
LUBRICATION
Lubricate all points .................................................................................................................... ..X ............... ..X .........
Renew engine oil ......................................................................................................................... ..X ............... ..X .........
Renew engine oil ■lter ..................................................................................................................................... ..X .........
Check level of all ■uid reservoirs, brake, clutch, battery, rear axle, transmission,
cooling system and windshield washer ................................................................................. “X ............... “X ..........
ENGINE
TCheck all drive belts; adjust if necessary .....................................................................................................................
TCheck all hoses, vacuum, air and water for condition and tightness ......................................................................... H
TRenew all air ■lter cleaner elements (air pump and carburetter) ................................................................................ ..
TCheck restrictor in rocker cover purge line for obstruction ......................................................................................
TAdjust valve rocker clearances ...................................................................................................................... “X .........
TCheck gulp valve operation (renew if necessary) .........................................................................................................
FUEL SYSTEM
TRenew fuel line ■lter .......................................................................................................................................................
TCheck condition of fuel ■ller cap seal ............................................................................................................................
TCheck fuel pipes and unions for cha■ng, corrosion and leaks ..................................................................................
TTop up carburetter piston dampers ................................................................................................................ ..X ..........
OSCILLOSCOPE AND COMBUSTION CHECK
TCheck distributor points, resistance and dwell .............................................................................................. ..X ......... ..
TRenew distributor points .................................................................................................................................................. .n
TCheck ignition timing and distributor advance or retard characteristics .................................................. ,.X .........
TCheck engine idle speed... ................................................................................................................................. “X .........
TCheck spark plugs (cruise and unload condition) ........................................................................................ ..X .........
TRenew spark plugs ...........................................................................................................................................................
TCheck distributor cap and wires ...................................................................................................................... ..X .........
Check charging system output ........................................................................................................................ ..X .........
TPower check, engine cylinder comparison ...................................................................................................................
TCheck choke and carburetter fast idle speed setting .................................................................................... ..X .........
TCheck exhaust emission (CO HC) at idle ...................................................................................................... ..X .........
MGB. Issue2. 86842
.Maintenance 4

MAINTENANCE ‘SUMMARY
North America—continued
‘
A B
SAFETY .
Check/adjust front wheel alignment ..............................................................................................................................
Check visually hydraulic pipes, unions for cha■ng, leaks and corrosion ................................................................
Check/adjust handbrake operation ............................................................................................................. .. A...X .........
Inspect the brake pads for wear and discs for condition ......................................................................... .. ....X .................. ..
Inspect brake linings and pads for wear, drums and discs for condition ................................................................
Check/adjust headlights ................................................................. ........................................................... .. .WX .........
Check tyres visually, and report depth of tread, cuts in fabric, exposure of ply or cord structure,
lumps or bulges ......................................................................................................................................... .. ....X .........
Check wiper blades for condition .................................................................................................................................
Check condition, operation and security of seats, seat belts/interlock ....................................................................
Check operation of all door locks and window controls ............................................................................................
ROAD TEST
Ensure that operation of vehicle is satisfactory and report all items requiring attention ................... .. ....X .........
24,000—miles or 24-month intervals
*TRenew all drive belts
*TCheck air pump (correct or renew if necessary)
*TRenew adsorption canister
*TRenew distributor cap and wires
* Clean overdrive ■lter
36,000—miles or 36-month intervals
*Renew all hydraulic brake seals
The maintenance summary on this and the preceding page is the minimum service required to maintain your vehicle
under normal driving conditions. For other than normal driving conditions, and those caused by seasonal changes,
we recommend that you consult your Dealer.
MGB. Issue 1. 86842 MaintenanceS ‘
.A

LUBRICATION CHART
R.H.D. and L.H.D. EXCEPT NORTH AMERICA
U
IND23IB
NOTEz—Ensure
that the vehicle is standing on alevel surfacewhen checking the oil levels.
Weekly
(1) ENGINE. Check oil level, and top up if necessary.
Every 6,000 miles or 6months
(2)
(3)
(4)
(5)
ENGINE. Drain and re■ll with new oil.
ENGINE OIL FILTER. Remove the disposable cartridge, fit
new.
Early cars: Drain filter, wash ■lter bowl in fuel and fit new
element.
CARBURETTERS. Top up carburetter piston dampers.
ACCELERATOR. Lubricate accelerator control linkage, cable
and pedal fulcrum.
DISTRIBUTOR. Lubricate all parts asnecessary.
REAR AXLE. Check oil level, and top up if necessary.
GEARBOX AND OVERDRIVE. Check oil level, and top up
if necessary.
(9)
(10)
(11)
(12)
AUTOMATIC TRANSMISSION. Check fluid level, and top
up if necessary. .
FRONT SUSPENSION (6 nipples)
HAND BRAKE CABLE (1 nipple) .
AND MECHANICAL LINKAGE “mm W“ a
PROPELLER SHAFT (1 nipple) grease
gun-
LOCKS AND HINGES. Lubricate the bonnet releasesafety
catch and all looks and hinges.
Give three or four
Every 24,000 miles or 24 months
(13) GEARBOX WITH OVERDRIVE. Drain, clean overdrive
filters and refill with new oil.
Optional lubrication at 3,000 miles 01’3months
(1) ENGINE. Check oil level and top up if necessary.
Recommendedoils and greasesaregiven at the end of the manual
MGB. Issue1. 86842

LUBRICATION CHART
NORTH AMERICA
IND23|E
NOTE :—Ensure that the vehicle is standing on alevel surface when checking the oil levels.
Weekly
(1) ENGINE. Check oil level, and top up if necessary.
Lubrication service every 3,000 miles or 3 months
(2) ENGINE. Drain and re■ll with new oil.
(3) THROTTLE AND CHOKE. Lubricate throttle and
choke control linkages, cables, and accelerator pedal
fulcrum.
(4) REAR AXLE. Check oil level, and top up if necessary.
(5) GEARBOX AND OVERDRIVE. Check oil level, and
top up if necessary. ‘
(6) PROPELLER SHAFT (l nipple) Give three or four
(7) FRONT SUSPENSION (6 nipples) strokes with a
(8) HAND BRAKE CABLE (l nipple) grease gun.
(9) WHEELS AND HUBS. Lubricate wire wheel and hub
splines.
Recommended oils and greases are given at the end of the manual I"
~.
3‘ '.
MGB. Issue1. 86842
LOCKS, HINGES AND LINKAGES. Lubricate all
door, bonnet and boot locks and hinges; and the hand
brake mechanical linkage.
FRICTION POINTS. Spray lubricant on all friction
points. .r
‘A’ service every 6,000 miles or 6 months; AND ‘3’ service
every 12,000 miles or 12 months
(10) ENGINE OIL FILTER. Remove disposable cartridge,
■tnew. '-'i
(11) CARBURETTERS. Top up carburetter piston dampers.
(12) DISTRIBUTOR. Lubricate all parts as necessary.
Every 24,000 miles or 24 months ‘..
(13) GEARBOX WITHOVERDRJVE. Drain, clean over-
drive ■lter, re■ll with new oil. "- ~.
Maintenance 7

ENGINE
Type .. .. ..
Number of cylinders ..
Bore
Stroke _..
Capacity .. ..
Combustion chamber volume (valves fitted) ..
Firing order
Valve operation ..
Compression ratio: H.C. ..
LC. ..
Compression pressure: H.C.
L.C.
Torque: H.C. ..
L.C. ..
Engine idle speed (approx.)
Oversize bore: First ..
Max. ..
Crankshaft
Main journal diameter
Crankpin journal diameter ..
Crankshaft end-thrust
Crankshaft end-■oat
Main bearings
Number and type
Material .. ..
Length .. .. ..
Diametrical clearance
Undersizes
Connecting rods
Type .. .. ..
Length between centres
Big-end bearings
Type
Material .. ...
Length .. .. ..
Diametrical clearance
Undersizes
End-■oat on crankpin (nominal) ..
Pistons
Type .. .. .. ..
Clearance in cylinder: Top
Bottom ..
Number of rings ..
Width of ring grooves: Top ..
Second ..
Third
Oil control
Gudgeon pin bore
MGB. Issue7. 80619
GENERAL DATA
(18G/18GA)
18G, 18GA.
4.
3.16 in. (80.26 mm).
3.5 in. (89 mm.).
1798 c.c. (109.8 cu. in.).
42.5 to 43.5 c.c. (2.59 to 2.65 cu. in.).
1, 3, 4, 2.
Overhead by push-rod.
8.8 :1.
8.0 :1.
160 lb./sq. in. (11.25 kg./cm.2).
1301b./sq. in. (9.15 kg./cm.2).
1101b. ft. (15.2 kg.m.) at 3,000 r.p.m.
105 lb. ft. (14.5 kg.m.) at 3,000 r.p.m.
500 r.p.m.
.010 in. (.254 mm.).
.040 in. (1.016 mm.).
2.1262 to 2.127 in. (54.01 to 54.02 mm.).
1.8759 to 1.8764 in. (47.648 to 47.661 mm.).
Taken on thrust washers at centre main bearing.
.004 to .005 in. (.10 to .13 mm.).
Three thinwall.
Steel-backed copper-lead.
1%in. (28.5 mm.).
.001 to .0027 in. (.0254 to .068 mm.).
—.010,~.020, —.030 and —.040 in. (—.254, «.508,
—.762 and «1.016 mm.).
Angular-split big-end, split clamp small-end.
6.5 in. (165.1 mm.).
Shell.
Steel-backed copper-lead.
.995 to 1.005 in. (25.2 to 25.52 mm.).
.001 to .0027 in. (.0254 to .068 mm.).
—.010,—.020, —.030 and —.040 in. (—.254,_—.508,
—.762 and —1.016 mm.).
.008 to .012 in. (.20 to .30 mm.).
Aluminium solid skirt.
.0036 to .0045 in. (.091 to .121 mm.).
.0018 to .0024 in. (.045 to .060 mm.).
4(3 compression, 1'oil control).
.064 to .065 in. (1.625 to 1.651 mm.).
.1578 to .1588 in. (4.008 to 4.033 mm.).
.7501 to .7503 in. (19.052 to_“19.057 mm.).
GeneralData 1

GENERAL DATA—continued
(lSG/lSGA—continued)
Piston rings
COMPRESSION
Type: Top .. .. ..
Second and third
Width: Top .. ..
Second and thir
Fitted gap: Top .. .. ..
Second and third ..
Ring to groove clearance: Top .. ..
Second and third
OIL CONTROL
Type ..
Width .. ..
Fitted gap .. .. ..
Ring to groove clearance
Gudgeon pin
Type
Fit in piston
Diameter (outer)
Camshaft
Journal diameters: Front
Centre
Rear ..
. . . . . Front
Bearmg liner 1n81dedlameter
(reamed after fitting): centre
Rear
Diametrical clearance
End-thrust
End-■oat
Cam lift ..
Drive ..
Timing chain ..
Tappets
Type .. ..
Outside diamete
Length ..
Rocker gear
ROCKER SHAFT
Length
Diameter
ROCKER ARM
Bore .. .. .. ..
Rocker arm bush inside diameter
Ratio ..
Valves
Seat angle: Inlet and exhaust
Head diameter: Inlet
Exhaust ..
Stem diameter: Inlet
Exhaust ..
Stem to guide clearance: Inlet ..
Exhaust
Valve lift: Inlet and exhaust
GeneralData 2
.«1
Parallel 1
Tapered J
.0615 to .0625 in. (1.562 to 1.587 mm.).
cast iron—molybdenum filled.
.012 to .017 in. (.304 to .431 mm.).
1.0015 to .0035 in. (.038 to .088 mm.).
Slotted scraper.
.1552 to .1562 in. (3.94 to 3.96 mm.).
.012 to .017 in. (.304 to .431 mm.).
.0016 to .0036 in. (.04 to .09 mm.).
Semi-■oating.
Free-fit at 20°C. (68 °F.).
.7499 to .7501 in. (19.04 to 19.05 mm.).
1.78875 to 1.78925 in. (45.424 to 45.437 mm.).
1.72875 to 1.72925 in. (43.910 to 43.923 mm.).
1.62275 to 1.62325 in. (41.218 to 41.230 mm.).
1.79025 to 1.79075 in. (45.472 to 45.485 mm.).
1.73025 to 1.73075 in. (43.948 to 43.961 mm.).
1.62425 to 1.62475 in. (41.256 to 41.269 mm.).
.001 to .002 in. (.0254 to .0508 mm.).
Taken on locating plate.
.003 to .007 in. (.076 to .178 mm.).
.250 in. (6.35 mm.).
Chain and sprocket from crankshaft.
%in. (9.52 mm.). pitch x52 pitches.
Barrel with ■at base.
1%in. (20.64 mm.).
2.293 to 2.303 in. (58.25 to 58.5 mm.).
143% in. (.356 mm.).
.624 to .625 in. (15.85 to 15.87 mm.).
.7485 to .7495 in. (19.01 to 19.26 mm.).
.6255 to .626 in. (15.8 to 15.9 mm.).
1.4 :1.
451/24).
1.562 to 1.567 in. (38.67 to 38.80 mm.).
1.343 to 1.348 in. (34.11 to 34.23 mm.).
.3422 to .3427 in. (8.68 to 8.69 mm.).
.3417 to .3422 in. (8.660 to 8.661 mm.).
.0015 to .0025 in. (.0381 to .0778 mm.).
.002 to .003 in. (.0508 to .0762 mm.).
.3645 in. (9.25 mm.).
MGB. Issue7. 80619