Carburetors

The carburetor is the part of an automobile engine that converts liquid fuel into vapor. This is mixed with a certain amount of air that allows combustion in the cylinders. All gasoline vehicles have carburetors, including boats and light aircraft. Carburetors are generally found in small engines and in older automobiles, especially those used in stock car racing. Most engines have only one carburetor though most modern engines that have bigger engines or more than 4 cylinders use multiple carburetors.The history of carburetors can be traced to the development of the wick carburetor by Donate Bank, a Hungarian engineer in 1893. Frederick and his brother built the first petrol driven car in 1896. Then in 1900, they built a 2-cylinder engine using the new wick carburetor. This car was taken on a successful 1000-mile tour, marking an important landmark in the use of the carburetor in automobiles.

There are two kinds of carburetors, downdraft carburetors, wherein the flow of air is downwards; and side-draft, wherein the flow of air is sideways. Most automobiles in the U.S. use downdraft carburetors while side draft carburetors are found more in Europe. Carburetors are also classified as fixed choke and constant depression or variable choke. The variable choke carburetors are generally used in the UK because they are simple in adjustment and maintenance. Carburetor’s efficiency depends on its capacity to provide the right mixture of fuel and air under each circumstance of engine operation. The different engine conditions are cold start, idling or slow running, acceleration, high speed/high power at full throttle and cruising at part throttle (light load).

The main parts in a carburetor are an open pipe, which is the carburetor’s “barrel” or “throat” through which the air reaches the engine. The butterfly valve or the “throttle”, a rotating disc in this pipe, controls the air flow through the carburetor throat, which influences the power and speed of the engine. This throttle is connected to the accelerator of the vehicle. The major manufacturers of carburetors are Amal Ltd., Automate, Carter, Holley, Pierburg, Rochester, Solex, Stromberg, SU, Walbro and Tillotson (small engines), Briggs and Stratton, Villiers, Weber, and Zenith.