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The BMC C-Series was a straight-6 automobile engine produced from 1954 to 1971. Unlike the Austin-designed A-Series and B-Series engines, it came from the Morris Engines drawing office in Coventry and therefore differed significantly in its layout and design from the two other designs which were closely related. Displacement was 2.6 to 2.9 L (2,912 cc) with an 83.3 mm bore and 88.9 mm stroke. ==Mission== The new engine was required to replace BMC's inherited diverse collection of 2½-litre engines made to prewar designs and Austin's wartime designed four-cylinder BS1. A long-stroke engine, though closer to square than BMC contemporaries, with a cast iron block and cylinder head using Weslake patents its overhead valves were operated by pushrods. Previously Rileys used high-mounted twin camshafts with short pushrods and Wolseleys used single overhead camshafts. There appear to have been plans for a twin-camshaft version for the new Rileys and Wolseleys corresponding with the —unreliable— MGA Twin Cam but these plans were dropped in 1955. It was given a not seven but four main bearing crankshaft which later proved a restriction on power output and engine speed. The C-Series has always been considered an engine that was both large and heavy for its capacity and power output, initially proving to have little benefit, aside from the greater refinement of six-cylinders, over the Austin-designed four-cylinder 2.6-litre BS1 engine installed in the Austin A90 Atlantic and Austin-Healey 100. Austin's engineers attributed this to poor head design. Certainly in 1957 the Healey was given a twelve-port head increasing output 15bhp or fifteen percent. In 1959 carburetters were revised and replaced. In 1961 the inlet tract was improved, exhaust timing was adjusted and twin exhausts added. Later in 1961 the saloon engines were slightly detuned and the Healey version's performance upgraded, probably by Weslake. Then the Austin Healey Mark III was announced. The C-Series was also less efficient than, and in engineering terms was a retrograde step from Nuffield's engines: the Riley-designed Riley 2½-litre Big Four twin-cam four-cylinder unit fitted in the Riley RM series, and Riley's prewar cars, and the Wolseley designed Wolseley 2.2-litre straight six with a single overhead camshaft used in the Morris Six MS version of the Wolseley 6/80 which dated back to the early 1920s. The Austin BS1 had begun as a late wartime Rix and Bareham design, two-thirds of a Bedford-based wartime truck engine, for a 2.2-litre ohv unit intended for a British jeep which became the civilian Austin Champ. Its use spread to Austin's Sixteen, their light commercial vehicles and the FX3 taxi.〔Time for Sixteens to come of age. Martyn Nutland. ''Austin Times'', April 2003, Volume 1, Issue 1.〕 However the C-Series was much more reliable than these units and cheaper to manufacture. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「BMC C-Series engine」の詳細全文を読む スポンサード リンク
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