BMC B-series engine

B-Series
Overview
Manufacturer	BMC
Production	1954–1980
Layout
Configuration	I4 and I6
Displacement	1.2 L, 1.5 L, 1.6 L, 1.8 L (I4) 2.4 L (I6)
Cylinder bore	65.5–80.26 mm (2.6–3.2 in)
Piston stroke	89 mm (3.5 in)
Cylinder block material	Cast iron
Cylinder head material	Cast iron Aluminum (Twin-Cam)
Valvetrain	OHV DOHC (Twin-Cam)
Combustion
Fuel system	Carburetor
Fuel type	Gasoline & diesel versions
Cooling system	Water-cooled
Chronology
Successor	BMC E-Series BL O-Series

The BMC B-series was a straight-4 cylinder internal combustion engine mostly used in motor cars, created by British company Austin Motor Company.

Design

The precursor of the "B" series engine was a 1200 cc Overhead Valve (OHV) engine which was used in the 1947 Austin A40 Devon. This A40 Devon engine was based on an earlier pre-war Side-valve design. Austin realised that eventually they would need an engine that could power many of its forthcoming medium-sized cars, and this would require an engine of at least 1500 cc capacity. Since the A40 Devon engine could not have its capacity enlarged, a new engine needed to be designed and built.

The design of this new engine commenced around January 1952, and was designated as the "B" series. Although superficially similar, it was longer and heavier than the A40 Devon engine with the advantage of being bored out, whereby the piston cylinders diameter was increased to provide a larger capacity if needed. Originally of approximately 1.2 Litre capacity, later displacements ranged widely from 1.2 L to 2.4 L, the latter being an Australia only production six-cylinder variant. The most common engine sizes were 1.5 L and 1.8 L and saw service in a number of vehicles. This included a version of the engine built under license in India by Hindustan Motors for its Ambassador series of cars. Petrol versions were produced in the greatest numbers, but diesel versions exist for both cars and marine applications.

Construction

The engine was of conventional construction with a one-piece crankcase and cylinder block in cast iron with the crankcase extending down to the lowest level of the main bearing caps; with acylinder head also usually in cast iron and a sump 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 and locknuts on the rocker arms. The B-Series shares many design features (such as the heart-shaped combustion chambers and siamese inlet ports designed by Harry Weslake), as well as its basic layout and general appearance, with the smaller A-Series engine, but differed by having a full-depth skirt to the block. This provided excellent bottom-end strength which made the engine highly durable and suitable for developing into diesel versions in later years.

Engine types

1.2 litre engines

The 1.2L (1199.6 cc) version was the first version of the engine. The bore was 65.5 mm (2.58 in) and the stroke 89 mm (3.5 in). The maximum power output was 39 bhp (29 kW) at 4300 rpm.

After the formation of British Motor Corporation (BMC) it was used in the following vehicles:

• 1954–56 Morris Cowley
• 1952-54 Austin A40 Somerset
• 1954–56 Austin A40 Cambridge
• 1954–55 Nash Metropolitan 1200 (used unique "2G" engine prefix)
• Massey-Harris Combine Harvester

1.5 litre engines

B-Series 1500 engine in a Nash Metropolitan Series 3

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 series II and Austin Cambridge. In 1957, it was used in the original MGA. Output in twin carburettor form was 68–72 bhp (51–54 kW) and 55 bhp (41 kW) with a single carburettor. Bore was 73.03 mm (2.875 in) and stroke was 89 mm (3.5 in).

There was also a diesel version of this engine size. Power output was 40 bhp (30 kW) at 4,000 rpm and torque 64 lbf·ft at 1,900 rpm.

Applications:

• 1954–61 Morris Oxford series II, III, V & VI
• 1956–59 Morris Cowley
• 1956–62 Nash Metropolitan 1500
• 1955–58 MGA
• 1953–61 MG Magnette ZA, ZB, & Mark III
• 1956-61 Morris J2 1/2-ton vans
• 1956–58 Austin A50 Cambridge
• 1958–61 Austin A55 Cambridge
• 1956–58 Wolseley 15/50
• 1957–65 Wolseley 1500
• 1958–61 Wolseley 15/60
• 1957–61 Morris Commercial JB-type 1/2 - Ton vans
• 1957-61 ((Austin 101)) 1/2 - Ton vans
• 1957–65 Riley 1.5
• 1959–61 Riley 4/68
• 1959–65 Rochdale Olympic
• 1958–62 Morris Major and Austin Lancer Series I/II
• 1957–63 Tempo Matador
• Hindustan Ambassador
• International Harvester "Metro-Mite" delivery truck
• Navigator 1500 marine engine
• 1958–60 TVR Grantura Mark I
• 1960–62 TVR Grantura Mark II & IIA
• 1958-1959 Elva Courier

Twin-Cam engines

A special Twin-Cam (DOHC) version of the 1588 cc B-series engine was produced for the MGA. Output was 108 bhp (81 kW) at 6700 rpm in the high-compression (9.9:1) version and 100 bhp (75 kW) in the optional low-compression (8.3:1) version. The engine block was cast iron, but the crossflow eight-port cylinder head was of aluminium alloy. Drive to the twin camshafts was by chain from a gear-driven, 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. The piston burning habits — thought to be the result of ignition timing — was later discovered to be due to a vibration induced lean burn situation involving the float bowls, easily correctable by flexibly mounting the carburettors.

A total of 2,111 cars were built, in both coupé and roadster versions.

A very few engines with the special displacement of 1762 cc were produced for racing purposes.

Applications:

• 1958–60 MGA Twin-Cam

1.6 litre engines

The engine was enlarged to 1.6 L (1588 cc) in 1958 by increasing the bore to 75.4 mm (2.97 in).

Applications:

• 1959–61 MGA 1600
• 1960–62 TVR Grantura Mark II, IIA
• 1959-61 Elva Courier Mark II

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 (3.00 in).

Applications:

• 1961–62 MGA Mark II
• 1961–69 Austin Cambridge A60
• 1961-67 Morris J2 1/2-ton vans
• 1961–71 Morris Oxford VI
• 1961–71 Wolseley 16/60
• 1961–69 Riley 4/72
• 1961–68 MG Magnette Mark IV
• 1961–67 Austin 152 & Morris J2 1/2-ton van
• 1974–78 Sherpa van
• 1962–64 Morris Major Elite
• 1963–66 Tempo Matador
• 1966–67 Hanomag Matador
• 1967–73 Hanomag F20, Hanomag F25, Hanomag F30, Hanomag F35
• 1970–73 Mercedes Benz L206, Mercedes Benz L306
• Navigator 1600 marine engine
• 1962–64 TVR Grantura Mark III
• 1963-64 Elva Courier Mark III

The 1622cc B-Series also formed the basis of the "Blue Streak" engine developed by BMC Australia for use in the locally-built Austin Freeway and Wolseley 24/80 models, both in turn variants of the existing Austin A60 Cambridge. The "Blue Streak" was an inline-6 development of the B-Series, adding two extra cylinders to create a 2433cc engine. Different market demands in Australia required the fitting of a six-cylinder engine to a car the size of BMC's mid-range Farina model and the corporate C-Series engien would not fit, requiring the development of the unique "Blue Streak" engine. Both models were withdrawn in 1965 and no further use of the engine was made.

1.8 litre engines

The engine was enlarged again to 1.8 L (1798 cc) in 1962. Bore was 80.26 mm (3.160 in) and stroke was still 89 mm (3.5 in). The engine at first had a three-bearing crankshaft with a five-bearing version appearing in 1964.

There was also a diesel version of this capacity, used in the Leyland Sherpa van, and built under license in Turkey for many years. It is still widely used on narrowboats on the canals of the UK.

Applications:

• 1954–80 Probe 16
• 1962–80 MGB
• 1964–75 BMC ADO17 ("Landcrab") Austin 1800
• 1967–72 BMC ADO17 ("Landcrab") Wolseley 18/85
• 1966–75 BMC ADO17 ("Landcrab") Morris 1800
• 1975–78 Princess 1.8
• 1971–78 Morris Marina 1.8
• 1964–67 TVR Grantura Mark III and IV
• 1964-65 Elva Courier Mark IV
• 1974–78 Leyland Sherpa van
• 1973–75 Hanomag F20, Hanomag F25, Hanomag F30, Hanomag F35
• 1973–77 Mercedes Benz L207
• 1973–78 Mercedes Benz L307

2.4 litre engines

There was a 2433 cc six-cylinder unit, named "Blue Streak", which was used in the Australian Austin Freeway and Wolseley 24/80.

Engine numbering

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

Numbering system, 1936 to 1956

Numbers were of the style "BP15GB" followed by the engines serial number, where:

• BP = B series engine with Pushrod (Overhead Valve)
• 15 = capacity
• G = MG (for full list of codes see reference below)
• B = This final letter denotes the engine version.

Numbering system, 1957 to 1970

Numbers were of 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)

Numbering system, 1970 onwards

Beginning in the early 1970s the numbering system was simplified to "18 V" plus a serial number, where 18 represents the capacity and V = vertical, i.e. longitudinal (in-line, not vee-arranged) engine with rear-wheel drive, and H = Horizontal, i.e. transverse engine with front-wheel drive.

There was sometimes a country indicator after the first part of the code, e.g. "18V-Z" was use for some United States (except California) MG MGB engines.

See also

• BMC A-Series engine

References

• Porter, Lindsay (1985). BMC and Leyland B-Series Engine Data. Osprey. ISBN 0-85045-597-9.

External links

• List of engine codes
• B series engine description at "the unofficial Austin Rover resource"