Zenith Carburetters was a British company making carburetors. In 1955 they joined with their major pre-war rival Solex Carburetters and over time the Zenith brand name fell into disuse. The rights to the Zenith designs was owned by Solex UK (a daughter company of Solex in France). Image File history File links Zenith. ... Stromberg side-draft carburetor The carburetor, carburettor, or carburetter (see spelling differences), also called carb (in North America) or carbie (chiefly in Australia) for short, is a device that mixes air and fuel for an internal-combustion engine. ... 1955 (MCMLV) was a common year starting on Saturday of the Gregorian calendar. ... Solex was a French manufacturer of carburetors and powered bicycles. ...

Stromberg carburetor in a Saab 90

Stromberg carburetor dashpot

The big products of Zenith were the Zenith-Stromberg carburetors used in MGs, Saab 90s and early 99s and 900s, 1969-1972 Volvo 140s and 164s, and some 1960s and 1970s Triumphs, for instance the Triumph Spitfire used Zenith IV carburetors in the North American market. In Australia the CD-150 and CDS-175 models were fitted to the hi performance triple carburetored Holden Torana GTR-XU1. Image File history File linksMetadata Download high resolution version (725x610, 450 KB)Stromberg carburetor in a Saab 90. ... Image File history File linksMetadata Download high resolution version (725x610, 450 KB)Stromberg carburetor in a Saab 90. ... Saab 90 is also the name of an aeroplane, the Saab 90 Scandia. ... Image File history File linksMetadata Strombergcarb2. ... Image File history File linksMetadata Strombergcarb2. ... MG is a British marque that has produced sports cars since 1924, although none have been made since MG Rover went bankrupt in the spring of 2005. ... Saab 90 is also the name of an aeroplane, the Saab 90 Scandia. ... The 99 was an automobile produced by Saab from 1969 to 1984. ... See Saab 900 (NG) for the 1994–1998 Saab 900 model. ... The Volvo 140 is an automobile from Volvo. ... The Volvo 164 was an automobile manufactured by Volvo from 1968 to 1975. ... Triumph Logo (1978 version) 1934 Triumph Gloria Six 1937 Triumph Dolomite Roadster 1974 Triumph GT6 Coupé The Triumph Motor Company had its origins in 1885 when Siegfried Bettmann (1863-1951) and Moritz (Maurice) Schulte started producing Triumph bicycles in Coventry, England. ... 1971 Triumph Spitfire MKIV The Triumph Spitfire was a small British two-seat sportcar, introduced in 1962. ...

The Stromberg carburetor 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 carburetor. 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. To meet Wikipedias quality standards, this article or section may require cleanup. ... piston + connecting rod Components of a typical, four stroke cycle, DOHC piston engine. ... This article needs to be cleaned up to conform to a higher standard of quality. ...

The flow of air through the venturi creates a reduced static pressure in the venturi. This pressure drop is communicated to the upper side of the piston via an air passage. The underside of the piston is in communication with atmospheric pressure. The difference in pressure between the two sides of the piston creates a force tending to lift the piston. Counteracting this force is the force of the weight of the piston and the force of a compression spring which is compressed by the piston rising; because the spring is operating over a very small part of its possible range of extension, the spring force approximates to a constant force. Under steady state conditions the upwards and downwards forces on the piston are equal and opposite, and the piston does not move. Static pressure is a term used in ventilation engineering, airspeed indication, fluid statics, hydraulics and flow measurement. ...

If the airflow into the engine is increased - by opening the throttle plate, or by allowing the engine revolutions to rise with the throttle plate at a constant setting - the pressure drop in the venturi increases, the pressure above the piston falls, and the piston is sucked upwards, increasing the size of the venturi, until the pressure drop in the venturi returns to its nominal level. Similarly if the airflow into the engine is reduced, the piston will fall. The result is that the pressure drop in the venturi remains the same regardless of the speed of the airflow - hence the name "constant depression" for carburettors operating on this principle - but the piston rises and falls according to the speed of the airflow. In an engine, the throttle is the mechanism by which the engines power is increased or decreased. ...

Since the position of the piston controls the position of the needle in the jet, and thus the open area of the jet, while the depression in the venturi sucking fuel out of the jet remains constant, the rate of fuel delivery is always a definite function of the rate of air delivery. The precise nature of the function is determined by the tapered profile of the needle. With appropriate selection of the needle, the fuel delivery can be matched much more closely to the demands of the engine than is possible with the more common fixed-venturi carburettor, an inherently inaccurate device whose design must incorporate many complex fudges to obtain usable accuracy of fuelling. The well-controlled conditions under which the jet is operating also make it possible to obtain good and consistent atomisation of the fuel under all operating conditions.

This self-adjusting nature makes the selection of the maximum venturi diameter (colloquially, but inaccurately, referred to as "choke size") much less critical than with a fixed-venturi carburettor.

To prevent erratic and sudden movements of the piston it is damped by light oil in a dashpot (under the white plastic cover in the picture) which requires periodic topping up. A dashpot is a mechanical device which resists motion via viscous friction. ...

See also

• Zenith (disambiguation) for other companies named Zenith.
• SU carburetor, works with the same principle.