The BMC B-Series was a straight-4 automobile engine family created as a larger alternative to the company's A-Series. Displacements ranged from 1.2 L, 1.6 L, and even 2.4 L.

The engine was of conventional construction with a one piece crankcase and cylinder block in cast iron with cylinder head also usually in cast iron. The sump was made from pressed steel. Early engines used a three bearing crankshaft but later engines used five bearings. On all except the rare twin overhead camshaft variant the camshaft, which was chain driven and mounted low in the block, operated the overhead valves via pushrods and rocker arms. The two inlet ports in the non-crossflow cylinder head were shared between cylinders 1 + 2 and 3 + 4 and the three exhaust ports between cylinder 1, 2 + 3 and 4. Valve clearance was adjustable by screws on the rocker arms with access to the tappets by two side covers on the engine block, this feature being a probable hang over from side valve engine design.

 

Engine numbering

There were two series of engine numbers used as BMC changed the system at the end of 1956.

Early numbering system

Numbers were in the style BP15GB plus a serial number where:

• B = B series engine
• P = Pushrod
• 15 = capacity
• G = MG (for full list see Later numbering system below)
• The final letter is the version of the engine.

1957-1970 numbering system

Numbers were in the style 15GB-U-H plus a serial number where:

• 15 = capacity
• G = MG (other letters were: A = Austin, B = Industrial, H = Miscellaneous, J = Commercial, M = Morris, R = Riley, V = Vanden Plas and W = Wolseley )
• B = B series engine
• U = Central gear change (other letters were: A = Automatic, M = Manumatic clutch, N = Column change, O = Overdrive and P = Police)
• H = High compression (alternatively L = Low compression)

1970 onwards numbering system

Numbers were simplified to 16V plus a serial number where 16 represents the capacity and V = vertical ie in-line engine with rear wheel drive and H = Horizontal ie transverse engine with front wheel drive. There was sometimes a country indicator after the first part of the code eg 18V-Z was use for some United States(except California) MGB engines.

Automobiles using the B-Series

Examples of cars using a version of the B series engine:

• Alexis GT
• Austin A40 Dorset, Devon and Somerset
• Austin 18
• Austin 1800/Morris 1800
• Austin A50
• Austin A55
• Austin A60
• Austin Lancer (Australian model based on Riley 1.5 and Wolseley 1500)
• Elva Courier
• Gilbern GT
• Ginetta G11
• Hindustan Ambassador
• Lanchester Sprite
• Lotus Eight
• Morris Cowley/Morris Oxford
• Morris Marina
• Morris Major (Australian model based on Riley 1.5 and Wolseley 1500)
• Metropolitan 1500
• MG A
• MG B
• MG Magnette
• Ogle 1.5
• Princess 1800
• Riley 1.5
• Riley 4
• Rochdale Olympic
• TVR Grantura
• TVR Vixen
• Wolseley 15
• Wolseley 1500
• Wolseley 16
• Wolseley 18

Engine Types

1.2 litre engines

The 1200 cc was the first version of the engine and appeared in the 1947 Austin A40 Devon and Dorset. The bore was 65.5 mm and the stroke 89 mm. The maximum power output was 40 bhp at 4300 rpm. Later versions of the engine differed significantly from this early version.

• 1947-1952 Austin A40 Devon and Dorset
• 1952-1954 Austin A40 Somerset
• Austin A40 Cambridge 1954-1956
• 1954-1962 Nash Metropolitan 1200
• Massey-Harris Combine Harvester

1.5 litre engines

The 1.5 L (1489 cc) version was first used in 1953 in the MG Magnette ZA in twin carburettor version and in 1954 in the Morris Oxford and Austin Cambridge. In 1957 it was used in the original MGA. Output in twin carburettor form was 68 to 72 bhp (51 to 54 kW) and 55 bhp with a single carburettor. Bore was 73.025 mm (2.9 in) and stroke was 89 mm (3.5 in).

There was also a diesel version of this engine size. Power output was 40bhp at 4,000rpm and torque 64lb ft at 1,900rpm.

Applications:

• 1954-1971 Morris Oxford
• 1955-1958 MGA
• 1954-1962 Nash Metropolitan 1500
• 1953-1968 MG Magnette
• 1956-1958 Austin A40 Cambridge
• 1956-1958 Wolseley 15/50
• 1957-1965 Wolseley 1500
• 1958-1961 Wolseley 15-60
• 1957-1965 Riley 1.5
• 1959-1961 Riley 4/68
• 1959-1965 Rochdale Olympic
• 1956-1961 Austin 152 & Morris J2 1/2 ton van
• 1958-1960 Morris Major Series I & II and Austin Lancer Series I & II
• Hindustan Ambassador
• Navigator 1500 Marine engine

Twin-Cam engines

A special Twin-Cam (DOHC) version of the 1.5 L B-Series engine was produced for the MGA. Output was 110 bhp (82 kW) in the high compression (9.9:1) version and 100 bhp (75 kW) in the normal (8.3:1) version. The engine block was cast iron but the crossflow cylinder head was of aluminium alloy. Drive to the twin camshafts was by chain using a half speed shaft running in the space that would have been occupied by the conventional camshaft. This engine gained a reputation for being unreliable in service, especially in the high compression version which needed high octane fuel, but this has now been largely overcome.

Applications:

• 1958-1960 MGA Twin-Cam

1.6 litre engines

The engine was enlarged to 1.6 L (1588 cc) in 1958 by increasing the bore to 75.41 mm (3 in).

Applications:

• 1958-1961 MGA 1600
• 1959-1961 Austin A55 Cambridge
• 1961-1971 Wolseley 16-60
• 1961-1969 Riley 4/72
• Navigator 1600 Marine engine

1.6 litre Mark II engines

The engine was enlarged to 1622 cc in 1961 with another bore increase, this time to 76.2 mm (3 in).

Applications:

• 1961-1962 MGA Mark II
• 1961-1967 Austin 152 & Morris J2 1/2 ton van
• 1974-1978 Sherpa van
• 1961-1963 Morris Major Elite
• 1971-1975 Morris Marina
• 1964-1975 Austin 1800
• 1964-1975 Morris 1800

1.8 litre engines

The engine was enlarged again to 1.8 L (1789 cc) in 1962. Bore was 80.26 mm (3.2 in) and stroke was 88.90 mm (3.5 in). The engine at first had a 3 bearing crankshaft with a 5 bearing version appearing in 1964.

There was also a diesel version of this capacity.

Applications:

• 1962-1980 MGB
• 1964-1975 Austin 1800
• 1967-1972 Wolseley 18-85
• 1964-1967 TVR Grantura

2.5 litre engines

There was a 2433cc six cylinder unit that was used in some Australian models such as the Austin Freeway.

External references

An enthusiastic and active worldwide owners club called the Cambridge-Oxford Owners Club caters for the 'B-series'-powered Farina and Pre-Farina cars and their 'Westminster' derived six cylinder 'C-Series' sisters. The club aims to keep the cars on the road, provides advice, spares and a social forum for enjoying the cars.

The Club can be contacted at: www.co-oc.org or UK phone number: 07966 249506

• Full list of engine codes
• B series engine description