Our Lotus has the basic configuration of a single Weber 40DCOE 2 on a Lotus alloy manifold. The performance of the basic engine is moderate, 66 HP at 4600 rev/min. The ports of our engine have been enlarged and the combustion chamber has been flowed moderately. Also, humps and edges in the inlet manifold have been smoothed out and the exhaust is 4-2-1. But most importantly, the engine is equipped with a fast road A2 cam. With the 0.06″ overbore our data show a power output of some 80 HP at 5200 rpm. Not a high reving engine but an engine with good midrange torque. This power figure has been used for jetting of the Weber extrapolating from the unmodified engine.
Basic 66 HP Modified 80 HP
Camshaft Ford A2
Choke 26 28
Aux. venturi 4.5 4.5
Main jet 115 125
Air jet 165 160
Emulsion tube F16 F16
Idle 45F9 45F9
Pump jet 65 65
With this setup up the car is lively and has no hesitation during acceleration.