Ford Lotus Twin Cam 8v Tuning Guide
The stuff legends are made of, the Lotus TC was THE engine of the Sixties, especially in cars such as the Ford Mk1 Cortina plus the Anglia, which was the first road-type car, albeit in prototype form, to carry the motor. Images of Jim Clark belting round a race track cocking a front wheel go hand in hand with this unit.
There are basically two Ford-derived Twinks, the Mk1 introduced in the Mk1 Cortina in 1963, and MkII, which was fitted in the MkII Cortina Lotus from March 1967 - this version was also fitted to the 1968 Escort Twin Cam. This is actually the better engine since it has a purpose-cast Lotus block (identified with a large L on the side but usually under an engine mount) as opposed to a mere graded Cortina 1500 block. As such, the engine was based on a Ford Pre-Crossflow with a Harry Mundy-designed, twin cam alloy head, with chain drive and eight valves.
Blocks were bored to 82.55mm from the Pre-Crossflow’s standard 80.96mm - hence the Mk2 having a thicker casting to more reliably carry the increased capacity that allowed 1558cc. These engines also had square mains caps - the same as 711M Crossflows, proper oil seals as opposed to the Mk1’s rope-type, plus, stronger 125E rods. The MkII engine also had sleeved tappet bores, better oil returns to the block, plus a 6-bolt flywheel fixing in the crank, which supersedes the earlier 4-bolt type.
In addition, you’ll also find a Twink in Lotus Elans and later Europas. Naturally, there were several versions of these too. The Special Equipment (S/E) with 115bhp was fitted to S2-S4’s, whilst the Elan Sprint received bigger valves (and has Big Valve on the rocker cover), higher compression, better cams and exhaust, resulting in 126bhp.
There is also a Stromberg - carbed engine, although most had a Weber DCOE type manifold cast into the head, which interchanges with the similar and occasionally fitted, Dellorto side draught.
Twinks do have a reputation for water pump failure but this is mostly due to the engine being left standing for long periods - the pump goes dry and rips the seal when it’s turned over. We have re-designed this area to incorporate a modular type water pump so that it’s easier to remove and replace. We also offer the water pump housing in two heights to suit standard or Crossflow based engines.
The latter is also a popular route for building a Twink since L-blocks are becoming scarce. In addition, the Crossflow block can be increased up to 1700cc obviously giving a performance increase too. We also stock the special spacing components required, for this conversion.
More power is reasonably straightforward with the engine responding well to head porting, cam change and 45DCOEs. A usable 140+bhp can be achieved with the right cams. Due to the age of most head castings, we would recommend getting the head checked over first to advise on how suitable it is for further improvements to be made. We stock a whole range of replacement and performance parts for this engine including forged pistons, steel cranks / rods, steel flywheels, camshafts, large valves, steel tappets and much more besides.