 Most production carbureted engines, as opposed to fuel-injected, have a single carburetor and a matching intake manifold that divides and transports the air/fuel mixture to the intake valves, though some engines (like motorcycle engines) use multiple carburetors on split heads.Multiple carburetor engines were also common enhancements for modifying engines in the USA from the 1950s to mid-1960s, as well as during the following decade of high-performance muscle cars, each carburetor feeding different chambers of the engine's intake manifold.Older engines used updraft carburetors, where the air enters from below the carburetor and exits through the top.