The carburetor - Old School rocks!

Most carbureted (as opposed to fuel-injected) engines have a single carburetor, though some engines use multiple carburetors. Older engines used updraft carburetors, where the air enters from below the carburetor and exits through the top. This had the advantage of never "flooding" the engine, as any liquid fuel droplets would fall out of the carburetor instead of into the intake manifold; it also lent itself to use of an oil bath air cleaner, where a pool of oil below a mesh element below the carburetor is sucked up into the mesh and the air is drawn through the oil covered mesh; this was an effective system in a time when paper air filters did not exist. Beginning in the late 1930s, downdraft carburetors were the most popular type for automotive use in the . In Europe, the sidedraft carburettors replaced downdraft as free space in the engine bay decreased and the use of the SU-type carburetor (and similar units from other manufacturers) increased. Small propeller-driven flat aircraft engines still use the updraft carburetor design.

The carburetor works on Bernoulli’s principle: the fact that moving air has lower pressure than still air, and that the faster the movement of the air, the lower the pressure. The throttle or accelerator does not control the flow of liquid fuel. Instead, it controls the amount of air that flows through the carburetor. Faster flows of air and more air entering the carburetor draws more fuel into the carburetor due to the partial vacuum that is created.

A4carb scheme