Floats for Holley 2-bbl and 4-bbl performance carburetors come in two basic designs: side hung and center hung. A side hung float is so-called because the float arm is attached to the side of the float and it is hung or pivoted form one side of the float bowl. A center hung float has its float arm attached to the float center and it is hung pr pivoted from the center of the float bowl. Holley float designs are manufactured in brass or nitrophyl, and they are interchangeable. The float material used in any particular carburetor is dependent on the carburetor usage. For example, carburetors designed to run on alcohol must use a brass float, carburetors set up for blow-through forced induction systems need to use nitrophyl floats, and carburetors used on a draw-through forced induction system or naturally aspirated could use either a brass or a nitrophyl float. Most Holley performance carburetors have externally-adjustable floats. This feature greatly facilitates one's ability to help keep the carburetor in perfect tune.
