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Throughout the years of production from May 1962 to Oct 1980 the MGB went through a number of changes and modifications brought about by improvements in safety & use regulations and general upgrades. The main specifications and changes are shown below;
MGB Tourer and MGB GT - produced from May 1962 to Nov 1967 (GT from Sep 1965). Roadster; GHN3, GT; GHD3.
 
Production of the first MGB Tourer (better known as a Roadster) on 22 May 1962.
Engine:
4 cylinder 80.26 x 88.9mm, 1798cc, CR 8.8:1, 2 x 1½in SU Carbs, 95bhp (net) at 5,400rpm. Maximum torque 110lbs ft at 3,000rpm.
Transmission:
Axle ratio 3.909:1. Overall gear ratios 3.909:1 (overdrive 3.14:1), 5.369:1 (overdrive 4.31:1), 8.656:1, 14.214:1, reverse 18.588:1. Gearbox with synchromesh on 2nd 3rd and 4th gears only. Optional Laycock de Normanville D Type overdrive with a ratio 0.802:1 from early 1963. 17.9mph/1,000rpm in top gear, 22.3mph/1,000rpm in overdrive.
Suspension and Brakes:
IFS, coil springs, wishbones, Anti-roll bar (optional on tourer until Chassis No 108039), lever-arm dampers; live rear axle, half-elliptic leaf springs, lever-arm dampers. Rack and pinion steering. 10.75in front disc brakes, 10 x 1¾in rear drums. 4.0in rims (Tourer disc), 4.5in rims (centre-lock wire) or 5.0in rims (GT disc).
Dimensions:
Wheelbase 7ft 7in; front track 4ft 1in; toe-in 1/16th to 3/32nd in. (1.5 to 2.3 mm.) (unladen); rear track 4ft 1.25in. Length 12ft 9.3in; width 4ft 11.7in; height (Tourer) 4ft 1.4in, (GT) 4ft 1.75in. Unladen weight 2,030lb (Tourer), 2190lb (GT).
MGB Mk II Tourer and GT - produced from Nov 1967 to Aug 1971.
Roadster; GHN4, GT; GHD4 to Sep/Oct 69 then Roadster; GHN5, GT; GHD5 from there on.


Specification as for Mk I MGB models except for:
Engine:
(Federal markets) 1971 model-year, CR 8.0:1, 2 SU carbs, 82bhp (DIN) at 5,400rpm. Maximum torque 97lb ft at 2,900rpm.
Transmission:
Axle ration 3.909:1. All-synchromesh gears, overall ratios 3.909:1 (overdrive 3.2:1), 5.4:1 (overdrive 4.43:1), 8.47:1, 13.45:1, reverse 12.098:1. Optional Laycock Type LH overdrive introduced with ratio of 3.14 . Optional automatic transmission, overall ratios 3.909:1, 5.668:1, 9.34:1, reverse 8.17:1. From 1970 model-year (Sep/Oct 69) wheels 4.5in rims, Rostyle sculptured steel pattern or optional centre-lock wire wheels as before.
Dimensions:
Unladen weight 2,140lb (Tourer), 2,260lb (GT)
MGB Mk III Tourer and MGB GT - produced from Aug 1971 to Oct 1980.
1972 model-year (Aug 71) to 1974 model-year (Aug 73) inclusive, specification as for MGB Mk II except for:

Optional automatic transmission deleted from end of 1973 model-year (Aug 73).
155-14 (Tourer), 165-14 (GT) radial-ply tyres standardized on British market from start of 1973 model-year (Aug 72): all markets 1974 model-year (Aug 73). Brake vacuum-servo standardized (British market) from start of 1974 model-year (Aug 73).
Sep 1974 start of Rubber bumper production.
Dec 1974 MGB GT no longer available in North America.
1975 model-year (Dec 74) and 1976 model-year (Sep 75) inclusive, specification as for Mk II and earlier Mk III models.
Engine:
British models now have a recalibrated power output of 84bhp (DIN) at 5,250rpm. Maximum torque 104lb ft at 2,500rpm.
Federal models: CR 8.0:1, Zenith-Stromberg carburettor. 65bhp (DIN) at 4,600rpm. Maximum torque 92lb ft at 2,500rpm. Overall gear ratios unchanged except optional overdrive 3.21. 21.8mph/1,000rpm in overdrive.
Dimensions:
Overall length 13ft 2.25in; height 4ft 2.9in. Otherwise as before. Unladen weight not affected.
From the start of 1977 model-year, specification as for earlier MGB models except for:
Suspension:
Front and rear anti-roll bars now standard.
Dimensions:
Unladen weight 2,253lb (Tourer) 2,260lh (GT).
MGB production ceased on 23 October 1980.
Service/Maintenance
Tyres:
Up to 1972:  5.60-14 cross ply tyres were fitted as standard - normal or whitewall versions.
1965 on:  155-14 (Roadster), 165-14 (GT) radial tyres were optional.
In 1975 GT Jubilee models with the V8 style wheels were fitted with 175HR-14 tyres.
From the start of rubber bumper production in 1974 tubeless 165SR-14 tyres were fitted to both Roadsters and GTs. North American cars had tubes until 1976.
Tyre Pressures:
5.60-14 cross ply:  Front 19lb./sq in (1.34kg./cm.²) Rear 22lb./sq in (1.55kg./cm.²).
Radial-ply tyres:  Front 21lb./sq in (1.48kg./cm.²) Rear 24lb./sq in (1.69kg./cm.²)
For sustained high speeds increase the above pressures by 6lb./sq in (0.42kg./cm.²)

Ignition:
Contact breaker gap:  0.014-0.016in (0.35-0.40mm).
Spark plug type:  Champion N9Y (or equivalent for other manufacturers).
Spark plug gap:  Up to 1976 - 0.025in (0.64mm), 1976 on - 0.035in (0.89mm).
Dwell angle:  Up to 1974 with Lucas 25D4 distributor - 60° ± 3°, 1974 on with Lucas 45D4 distributor 51° ± 5°.
Timing:
Pointer on timing case, notch on crankshaft pulley. Consult workshop manual, timing varies depending on engine version.
Valve Rocker Clearance:
Valve rocker clearance 0.015 in. (0.38 mm.) set when cold.
Batteries:
Up to 1974 two 6 volt batteries were used connected in series. From the start of rubber bumper car production in 1974 a single 12 volt battery was fitted.
Capacities
Fuel Tank:
Up to March 1965 - 10 Imp gallons (12 US gallons, 45.4 litres).
March 1965 on - 12.7 Imp gallons (14 US gallons, 54 litres).
On North American cars fitted with the evaporative loss system the capacity was effectively reduced to 10 Imp gallons (12 US gallons). This was from Oct 1969 in California and from Aug 1970 for all North American cars.
Oil:
Engine:  7.5 Imp pints (9 US pints, 4.26 litres) 20/50 multigrade.
Oil pressure idle: 10 - 25 lb sq in, normal: 50 - 80 lb sq in for all models.
Gearbox (3 synchro):  4.5 Imp pints (5.6 US pints, 2.56 litres) 20/50 multigrade.
Gearbox with overdrive (3 synchro):  5.5 Imp pints (6 US pints, 3.36 litres) 20/50 multigrade.
Gearbox (4 synchro):  5.25 Imp pints (6 US pints, 3 litres) 20/50 multigrade.
Gearbox with overdrive (4 synchro):  6 Imp pints (7 US pints, 3.4 litres) 20/50 multigrade.
Three-quarter floating rear axle (Banjo):  2.25 Imp pints (2.75 US pints, 1.28 litres) Hypoid SAE90EP
Salisbury semi-floating rear axle:  1.5 Imp pints (1.8 US pints, 0.85 litres).
Automatic gearbox:  10.5 Imp pints (12.7 US pints, 6 litres) Auto Trans fluid Type F.
Coolant:
Up to Nov 1967 (back filler radiator):  9.5 Imp pints (11 US pints, 5.4 litres). 7lb/sq in filler cap.
Nov 1967 to June 1976 (centre filler radiator): 11.5 Imp pints (13.8 US pints, 6.6 litres). 10lb/sq in filler cap.
June 1976 on:  12 Imp pints (14.4 US pints, 6.8 litres). 13lb/sq in filler cap.
Standard thermostat: 82°C (180°F) with 74°C (165°F) for hot climates and 88°C (190°F) for cold climates.
 The coolant should be mixed in accordance with the manufacturers instructions for the prevailing climatic conditions and changed at the recommended intervals.
Lubrication Chart:
Lubrication chart RHD and LHD except North America. Follow this link.
Lubrication chart North America. Follow this link.

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