BMC B-Series engine
| B-Series | |
|---|---|
 |
|
| Overview | |
| Manufacturer | BMC |
| Production | 1954–1980 |
| Combustion chamber | |
| Configuration | I4 and I6 |
| Displacement |
|
| Cylinder bore | 65.5–80.26 mm (2.6–3.2 in) |
| Piston stroke | 89 mm (3.5 in) |
| Cylinder block alloy | Cast iron |
| Cylinder head alloy |
|
| Valvetrain |
|
| Combustion | |
| Fuel system | Carburetor |
| Fuel type | Gasoline & diesel versions |
| Cooling system | Water-cooled |
| Chronology | |
| Predecessor | BMC A-Series engine |
| Successor | |
The BMC B-series was a straight-4 cylinder internal combustion engine mostly used in motor cars, created by British company Austin Motor Company.
The precursor of the "B" series engine was a 1200 cc Overhead Valve (OHV) engine which was used in the 1947-1952 Austin A40 Devon, and, in slightly modified form, in the 1953 Austin A40 Somerset. These engines in turn were 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. A major advantage was that it could be bored out, whereby the piston cylinders diameter could be 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.
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 a cylinder 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.
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Wikipedia