Manufactured from advanced phenolic thermo set plastic and engineered to withstand extreme high intake manifold temperatures, these spacers were designed to insulate and reduce heat flow to the carburettor keeping it cooler to allow a denser fuel mixture to enter the engine and produce more horsepower. Available to fit the standard Holley/Carter and Quadrajet four barrel bolt pattern in your choice of either an open centre or four hole straight bore design, these spacers measure 1" thick and are packaged complete with gaskets, studs, nuts and washers.