This listing is for a 'New Old Stock' set, which is sold as a set of two.

These dual choke carburetters - aka DU - with 13/4" in. diameter throttle bore, were used almost exclusively on the 'Coventry Climax' 11/2" litre twin cam engines.

Whilst they work on the basic S.U. principle they have an additional full throttle - diaphragm operated weakening device. It was necessary to introduce this weakening device to overcome excessive mixture spread between full throttle and part throttle conditions.

Without this device, it was found that correct part throttle tuning produced an over-rich condition at full throttle, and conversely correct full throttle tuning resulted in an over-weak mixture at part throttle.

One other feature on these instruments was the positioning of the float chamber between the two chokes of the carburetter.
This necessitated the use of a narrow rectangular doped cork float, which is satisfactory in petrol but cannot be used with methanol blends.

Note: we offer restorations of carburetters, if this unit shows as out of stock or if you need a unit restored please do contact us for details.

This part is restored condition, our process includes cleaning, machining as applicable, and the part has been inspected thoroughly for quality and functionality.