Carburettor Tuning and Testing: Factors to be Considered and Methods used in Testing a Carburettor for a Type Engine Available to Purchase

WHEN designing a carburettor for a given engine two main factors must be taken into consideration—the pressure drop over the carburettor and the metering characteristics. The pressure drop over the carburettor at full throttle causes a loss in available engine power; and in order to reduce this to a minimum the carburettor should be as large as possible consistent with reasonable mechanical size. The metering characteristics are, however, generally improved by using a small choke, and a compromise must be made between choke size and metering characteristics.