The Zenith Carburetter Company Limited was a British company making carburettors in StanmoreMiddlesex, founded in 1912 as a subsidiary of the French Société du carburateur Zénith.[1] In 1965,[2] the company joined with its 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 its much later products, Zenith produced carburettors that were standard equipment on some very early, brass eraautomobiles, including the Scripps-Booth.
Non-UK German Pierburg (Stromberg) carburettor in a Saab 90Non-UK German Pierburg (Stromberg) carburettor dashpotBritish made Zenith/Stromberg carburettors as installed on a 1969 Jaguar E-type 6cyl 4.2l engine
The Triumph Spitfire 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 Dennis Barbet (Standard Triumph) and Harry Cartwright (Zenith) 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") that admits fuel into the airstream at the venturi of 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.
The flow of air through the venturi creates reduced static pressure within it. 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 weight of the piston and the force of a compression spring that 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 upward and downward forces on the piston are equal and opposite, and the piston does not move.
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 upward, 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.
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 major drawback of the constant-depression carburettor is its unsuitability in high-performance applications.[citation needed] Since it relies on restricting air flow to produce enrichment during acceleration, the throttle response lacks punch. By contrast, the fixed choke design adds extra fuel under these conditions using its accelerator pump.
Fuel injection is the introduction of fuel in an internal combustion engine, most commonly automotive engines, by the means of a fuel injector. This article focuses on fuel injection in reciprocating piston and Wankel rotary engines.
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Rootes Arrow was the manufacturer's name for a range of cars produced under several badge-engineered marques by the Rootes Group from 1966 to 1979 in Europe, and continuing on until 2005 in Iran. It is amongst the last Rootes designs, developed with no influence from future owner Chrysler. The range is almost always referred to by the name of the most prolific model, the Hillman Hunter.
The Sunbeam Alpine is a two-seater sports roadster/drophead coupé that was produced by the Rootes Group from 1953 to 1955, and then 1959 to 1968. The name was then used on a two-door fastback coupé from 1969 to 1975. The original Alpine was launched in 1953 as the first vehicle from Sunbeam-Talbot to bear the Sunbeam name alone since Rootes Group bought Clément-Talbot, and later the moribund Sunbeam from its receiver in 1935.
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Société du carburateur Zénith was a French corporation specialized in the making of carburettors for both automotive and aerospace industries. Created in Lyon in 1909 by car manufacturer Rochet-Schneider, it was taken over in 1970 by German company DVG. One of the main carburettor manufacturers of the 20th century, it had factories in Lyon and abroad, including in the United States and the United Kingdom.
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