C-series engine
The C-Series engine was the shortest lived out of the triumvirate of BMC engines, and has since gained infamy for being the motive power behind of the MGC and Austin 3-Litre.
Unloved, but not unworthy
The C-Series engine first made an appearance in 1954 in the Austin A90 Westminster, and unlike the A and B-Series units, it was designed at the Morris engines drawing office in Coventry. As it was devised by a different set of engineers, it is unsurprising to learn that it shares little in common with the two smaller units.
One important difference, is that the camshaft and and pushrods are located on the plug side of the engine. The advatage of this is that it allows the designer to separate inlet ports. This advantage was negated somewhat by the fact that the main inlet gallery was cast in one with the head. This was fed through two ports via a "Y-shaped" branch manifold, from a single carburettor. A twin-carb set-up was effected by the use of a twin-port inlet manifold (as seen in the Wolseley 6/90).
The bottom-end employed a counter-balanced crankshaft with four main bearings; vibration was absorbed by a rubber damper. Like the B-Series, this engine employed Vandervell copper-lead bearings - but due to its newer design, this was used from the beginning. Bore and stroke were 79.4 x 89mm, the engine capacity was 2639cc and maximum power was 85bhp by 4000rpm (in the SU-carburetted Morris Isis) or 83bhp (in Zenith carburetted Austin version).
By 1957, this specification had improved (thanks to a raised compression ratio) to 92bhp at 4500rpm in the A95 Westminster and in twin-carburettor form, 102bhp at 4600rpm in the A105. This was the first BMC engine to produce in excess of 100bhp, when it was announced in the Austin-Healey 100/6 type BN4 in 1956. The following year, the 'Healey's output was upped significantly to 117bhp at 4750rpm, thanks to the introduction of a new cylinder head incorporating separate manifolds - it was in this form that the 'Healey achieved its first rallying victory.
When the Farina-styled A99 came along in 1959, the C-Series was expanded to meet the task. The expansion to 3-litres was effected by increasing the bore to 83.3mm, which resulted in an new engine capacity of 2912cc. Power was also up to 112bhp (gross) at 4750rpm; the Austin-Healey version developed a healthier 124bhp (net) at 4500rpm. Following this, the 'Healey was then a recipient of a triple-SU HS4 carburettor set-up, boosting the power still further to 132bhp.
For the 1968 launch of the Austin 3-Litre, a seven-bearing crankshaft was introduced, and it was in this form that the C-Series saw out its final days in this and the MGC. Production lasted until 1971.
With thanks to David Jacobs for his extra information.
Copyright © 2002-2003 Keith Adams
Related pages: