Lotus Twin Cam engine

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Commissioned by Colin Chapman to fit into his new Elan in the early ‘60s, the Lotus Twin-Cam engine was such a success that over 55,000 were to be made during its 14-year life span.

The powerful and lightweight Coventry Climax FWE engines used in the Elite suited the purpose perfectly, but they were very expensive to buy and the supply contract was falling due for renewal. Chapman took a standard Ford block and commissioned a new engine front plate and twin-overhead camshaft head with large valves and efficient porting to sit on top.

By the time the project had reached fruition, Ford had announced their new five-bearing engine for the Capri, its extra crankshaft rigidity making all the difference on these highly-strung units. Initially blocks were chosen from Ford’s foundry based on cylinder wall thickness. These were stamped with an A, although such was the volume needed that in the end, Ford produced special batches with thicker blocks stamped with an L for Lotus.

The irony is that these engines weren’t really twin-cams at all; they actually had three camshafts in total, the original Ford item remaining in place to drive the ancillaries! Winning race after race, they were the engine to have and remain highly desirable today, both within the racing and the rallying fraternity, especially so when they have the later L series block and big-valve head.

The unit in our sale today has both and is based on a desirable 701 block with the correct ‘L’ casting signifying that this is a genuine Lotus block from 1970. This was the most developed unit and used square main bearing caps and a 6 bolt crankshaft.

It was rebuilt in 1990 by TwinCam Techniques who ported and polished the head. It has a four-into-one stainless steel exhaust manifold, Sprint camshafts and Weber DCOE 40 carbs, a rolling road set-up by John Wilcox competition engines in 1993 showing that it produced a useful 95bhp at the wheels at 5,000 rpm when fitted into the vendor’s Westfield.

It was removed from the vehicle which was subsequently sold, the vendor keeping the Lotus engine as a spare for another vehicle. It had only covered around 3,000 road miles and was running well when removed.