Zenith carburettor

The Zenith Carburetter Company Limited was a British company making carburettors in Stanmore Middlesex founded in 1910. In 1965 they joined with their major pre-war rival Solex Carburettors and over time the Zenith brand name fell into disuse. The rights to the Zenith designs were owned by Solex UK (a daughter company of Solex in France).

While better known for their much later products, Zeniths were standard equipment on some very early, brass era automobiles, including the Scripps-Booth.

The big products of Zenith were the Zenith-Stromberg carburettors used in MGs, 1967-1975 Jaguar E-types, Saab 99s, 90s and early 900s, 1969-1972 Volvo 140s and 164s, and some 1960s and 1970s Triumphs.

The Triumph Spitfire for instance used Zenith IV carburettors in the North American market. In Australia the CD-150 and CDS-175 models were fitted to the high performance triple carburettored Holden Torana GTR-XU1.

Designed and developed by Denis Barbet (Standard Triumph) and Harry Cartwrite (Zenith) in order to break SU's patents, the Stromberg carburettor features a variable venturi controlled by a piston. This piston has a long, tapered, conical metering rod (usually referred to as a "needle") that fits inside an orifice ("jet") which admits fuel into the airstream passing through the carburettor. Since the needle is tapered, as it rises and falls it opens and closes the opening in the jet, regulating the passage of fuel, so the movement of the piston controls the amount of fuel delivered, depending on engine demand.

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