Lotus Twin Cam 681F 'L' Cylinder Block

Now available from QED, a brand new 681F ‘L’ Block!

Not to be confused with the current American Kent 711 tall-block, this new block is manufactured solely in the UK using BS1452 Grade 250 cast iron with a tensile strength of 250 N/mm².

The block has a number of advantages over the original; the water jacket has been reduced in size to increase the stiffness of the block, this has also allowed for bores greater than 86mm, a limitation of the original block. The cylinder bores themselves are now Siamese, allowing for a bore of up to 90mm, the crankcase area is now stronger with increased wall thickness and for bores of over 85mm, the cross drilling above the centre main bearing has been removed as this was identified as a weak spot with large bores (oil can be fed via one of the engine mount bolt holes).

The block has spent many hours on the dyno to ensure reliability and is now race proven, having so far seen two full seasons.

The introduction of this new block means it is now possible to build a completely new, race ready, Lotus Twin Cam and as you’d expect from QED, we have everything you need to do just that!

The block comes fully machined and bored to your requirements.