Phenolic Carburetor Spacer 1 Inch 4 Hole Center Fits Holley 4150-4160, Carter, Edelbrock and Other Square Bore Mounting Flange 4-Barrel Carburetors Mr GasketThis 1 inch tall phenolic thermoset plastic spacer insulates your carburetor against manifold heat keeping it cooler and helps prevent fuel percolation (also known as vapor lock) in hot weather. This can also allow for a denser fuel mixure to help increase performance in some applications, as well as provide additional plenum volume. 4 hole design fits Holley 4150 4160 4 barrel carbs as well as most Carter and Edelbrock models with a squarebore