All carburetors tested have been automatic fuel metering barrel types. All have aluminum bodies & stainless steel inner parts. Diameters tested are .475; .513; .625; & .750. The newest carburetors use a needle valve that is not tapered. This feature eliminates the condition that takes place when leaning tapered needles that are not concentric; the needle goes lean, then rich, only to go overlean suddenly.
