MG MGB, Full Specifications

Key Specifications

Spec	Value
Production Years	1962—1980
Manufacturer	MG (British Motor Corporation / British Leyland)
Assembly	Abingdon-on-Thames, Oxfordshire, England
Body Styles	2-door roadster, 2-door fastback coupe (GT)
Layout	Front engine, rear-wheel drive
Construction	Steel monocoque (unibody)
Wheelbase	2,311 mm (91.0 in)
Overall Length	3,886 mm (153.0 in) — chrome bumper; 4,064 mm (160.0 in) — rubber bumper
Overall Width	1,524 mm (60.0 in)
Overall Height	1,257 mm (49.5 in) — Roadster; 1,283 mm (50.5 in) — GT
Kerb Weight	920 kg (2,030 lb) — Roadster; 1,000 kg (2,205 lb) — GT
Fuel Tank Capacity	54.5 L (12.0 imp gal)
Boot Capacity	340 L (12.0 cu ft) — Roadster; 590 L (20.8 cu ft) — GT (seats folded)
Drag Coefficient	0.47 (Roadster), 0.43 (GT)

Engine Specifications

18G/18GA/18GB, B-Series 1798cc (3-Main Bearing, 1962—1964)

Spec	Value
Configuration	Inline 4, OHV, 8-valve
Displacement	1,798 cc
Bore x Stroke	80.26 mm x 88.9 mm
Compression Ratio	8.8:1
Power	71 kW (95 hp) @ 5,400 rpm
Torque	152 Nm (112 lb-ft) @ 3,000 rpm
Fuel System	Twin SU HS4 carburettors
Ignition	Contact breaker points
Valvetrain	Pushrod OHV, solid lifters
Oil Capacity	4.5 L (with filter)
Recommended Oil	20W-50 mineral
Redline	6,000 rpm

18GD/18GF/18GG/18GH/18GJ/18GK, B-Series 1798cc (5-Main Bearing, 1964—1974)

Spec	Value
Configuration	Inline 4, OHV, 8-valve
Displacement	1,798 cc
Bore x Stroke	80.26 mm x 88.9 mm
Compression Ratio	8.8:1 (early), 8.0:1 (late low-compression)
Power	71 kW (95 hp) @ 5,400 rpm
Torque	152 Nm (112 lb-ft) @ 3,000 rpm
Fuel System	Twin SU HS4 carburettors
Ignition	Contact breaker points / electronic (late models)
Valvetrain	Pushrod OHV, solid lifters
Oil Capacity	4.5 L (with filter)
Recommended Oil	20W-50 mineral
Redline	6,000 rpm

18V, B-Series 1798cc (Rubber Bumper, 1974—1980)

Spec	Value
Configuration	Inline 4, OHV, 8-valve
Displacement	1,798 cc
Bore x Stroke	80.26 mm x 88.9 mm
Compression Ratio	8.0:1
Power	63 kW (84 hp) @ 5,250 rpm (single carb, US spec)
Torque	137 Nm (101 lb-ft) @ 2,500 rpm
Fuel System	Single Zenith-Stromberg 175 CD carburettor
Ignition	Electronic
Valvetrain	Pushrod OHV, solid lifters
Emissions	Air pump, catalytic converter (US spec)

Rover V8, MGB GT V8 (1973—1976)

Spec	Value
Configuration	V8, OHV, 16-valve
Displacement	3,528 cc
Bore x Stroke	88.9 mm x 71.1 mm
Compression Ratio	8.25:1
Power	102 kW (137 hp) @ 5,000 rpm
Torque	263 Nm (193 lb-ft) @ 2,900 rpm
Fuel System	Twin SU HIF6 carburettors
Block Material	Aluminium
Weight	Lighter than B-series iron block

Transmission Options

Transmission	Type	Gears	Applications
BMC B-series 3-synchro	Manual	4-speed (1st unsynchronised)	1962—1967
BMC B-series 4-synchro	Manual	4-speed (all synchro)	1968—1980
BMC B-series + Laycock OD	Manual + overdrive	4-speed + OD on 3rd/4th	Various years, optional
Borg-Warner 35	Automatic	3-speed	1967—1973 (optional)
BL 3-speed auto	Automatic	3-speed	1973—1980 (optional)

4-Speed Manual Gear Ratios (All-Synchro, Non-OD)

Gear	Ratio
1st	3.44
2nd	2.17
3rd	1.37
4th	1.00
Reverse	3.10

Overdrive Ratios (Laycock LH Type)

Gear	Ratio
3rd + OD	1.10
4th + OD	0.82

Final Drive Ratios

Model	Ratio
MGB (standard)	3.909
MGB (overdrive)	3.909
MGB GT V8	3.07
MGB (automatic)	3.909

Suspension

Component	Front	Rear
Type	Independent, double wishbone	Live axle, semi-elliptic leaf springs
Springs	Coil	Leaf (semi-elliptic)
Dampers	Lever-arm hydraulic (early) / telescopic (late)	Lever-arm hydraulic (early) / telescopic (late)
Anti-roll Bar	Yes (standard from 1977; optional/aftermarket earlier)	No
Uprights	Kingpin (chrome bumper) / ball joint (rubber bumper)	N/A

Brakes

Component	Front	Rear
Type	Solid disc	Drum
Disc/Drum Diameter	273 mm (10.75 in)	254 mm (10.0 in)
Servo Assisted	Yes (from 1968)	—
ABS	Not available	—

Steering

Spec	Value
Type	Rack and pinion
Power Assist	Not available
Turns Lock-to-Lock	2.9
Turning Circle	9.8 m (32.0 ft)

Performance (Approximate, Period Road Tests)

Model	0—60 mph	0—100 km/h	Quarter Mile	Top Speed
MGB Roadster (chrome bumper)	11.0 s	11.8 s	18.0 s	170 km/h (106 mph)
MGB GT (chrome bumper)	12.2 s	12.9 s	18.5 s	168 km/h (105 mph)
MGB Roadster (rubber bumper)	13.5 s	14.2 s	19.2 s	158 km/h (98 mph)
MGB GT V8	7.7 s	8.2 s	15.8 s	201 km/h (125 mph)

Fuel Economy (Approximate, Mixed Driving)

Model	L/100 km	mpg (imperial)
MGB (chrome bumper, twin SU)	9.5	30
MGB (rubber bumper, single carb)	10.5	27
MGB GT (chrome bumper)	10.0	28
MGB GT V8	13.0	22

Tyre Specifications

Model	Standard	Upgrade
MGB (all)	165SR14	175/70R14, 185/70R14

Wheel Specifications

Spec	Value
Standard	14” x 4.5” steel (disc wheels)
Optional	14” x 4.5” wire wheels (60-spoke, centre-lock)
Wire Wheel Hub	Centre-lock knock-off (left-hand thread on right side)
Bolt Pattern (disc wheels)	4 x 114.3

Electrical

Spec	Value
System	12V negative earth
Battery	12V, 57 Ah
Charging	Dynamo (1962—1967) / Lucas alternator (1968—1980)
Headlights	7” sealed beam (early) / 7” H4 halogen (late)
Fuses	2 (early) / 4 (late) — yes, that’s correct

Interior Dimensions

Dimension	Value
Headroom (Roadster, hood up)	876 mm (34.5 in)
Legroom	1,067 mm (42.0 in)
Shoulder Width	1,219 mm (48.0 in)
Seats	2 (Roadster), 2+2 (GT — rear seats nominal)

Service Intervals

Service Item	Interval
Engine oil and filter	5,000 km or 6 months
Valve clearance adjustment	10,000 km
Contact breaker points	10,000 km
Spark plugs	20,000 km
Air filter	20,000 km
Carburettor service (SU damper oil, needle/jet check)	5,000 km
Coolant	24 months
Brake fluid	24 months
Gearbox oil	40,000 km
Rear axle oil	40,000 km
Kingpin greasing (chrome bumper)	5,000 km
Wheel bearing grease (wire wheels)	20,000 km
Hood replacement (as needed)	5—8 years (vinyl), 8—12 years (mohair)

Model Variants

MGB Roadster (Mk I, 1962—1967)

Spec	Value
Engine	B-series 1798cc (3-bearing to 1964, 5-bearing after)
Power	71 kW (95 hp)
Gearbox	4-speed, 3-synchro (1st unsynchronised)
Features	Pull-handle doors, 3-main-bearing engine (to 1964)

MGB Roadster (Mk II, 1967—1969)

Spec	Value
Engine	B-series 1798cc (5-bearing)
Power	71 kW (95 hp)
Gearbox	4-speed, all-synchro
Features	Push-button doors, all-synchro gearbox, alternator

MGB Roadster (Mk III, 1969—1974)

Spec	Value
Engine	B-series 1798cc (5-bearing)
Power	71 kW (95 hp)
Features	Recessed grille, improved interior trim

MGB Roadster (Rubber Bumper, 1974—1980)

Spec	Value
Engine	B-series 1798cc (18V, detuned)
Power	63 kW (84 hp)
Features	Polyurethane bumpers, raised ride height, single carburettor

MGB GT V8 (1973—1976)

Spec	Value
Engine	Rover 3528cc V8, aluminium block, chain-driven single camshaft
Power	102 kW (137 hp) @ 5,000 rpm
Torque	263 Nm (193 lb-ft) @ 2,900 rpm
Features	Alloy V8 engine, V8 badging, GKN alloy wheels, hydraulic tappets

MGB GT Anniversary (1975)

Spec	Value
Engine	B-series 1798cc (5-bearing, 18V)
Power	63 kW (84 hp) @ 5,500 rpm
Gearbox	4-speed all-synchro with overdrive on 3rd and top
Carburettor	Twin SU HIF4
Compression Ratio	9.0:1
Production	750 units
Features	Special British Racing Green paint, GT-only, chrome bumper spec with rubber bumper mechanicals, gold LE stripes

MGB Roadster LE (1980)

Spec	Value
Engine	B-series 1798cc (5-bearing, 18V)
Power	72 kW (97 hp) @ 5,500 rpm
Torque	142 Nm (105 lb-ft) @ 2,500 rpm
Carburettor	Twin SU HIF4
Gearbox	4-speed all-synchro
Production	420 units
Features	Final production run, special bronze metallic paint, front spoiler, alloy wheels, commemorative plaques

MGB GT LE (1980)

Spec	Value
Engine	B-series 1798cc (5-bearing, 18V)
Power	72 kW (97 hp) @ 5,500 rpm
Torque	142 Nm (105 lb-ft) @ 2,500 rpm
Carburettor	Twin SU HIF4
Gearbox	4-speed all-synchro
Production	580 units
Features	Pewter silver metallic paint, front spoiler, alloy wheels, velour trim, clock and illuminated switches, padded steering wheel

Production Numbers (Worldwide, Approximate)

Variant	Units
MGB Roadster (all years)	~513,000
MGB GT (all years)	~125,000
MGB GT V8	~2,591
MGB GT Anniversary (1975)	750
MGB Roadster LE (1980)	420
MGB GT LE (1980)	580
Total	~642,000