Edelbrock S/B Chevy RPM Air-Gap ManifoldEdelbrock part #7501 RPM Air Gap #7501 intake manifold is designed for 1955 86 262 400 c. i. d. Chevrolet V8 applications. The award winning RPM Air Gap intake manifold incorporates the same race winning technology that's used on our Victor Series competition intakes. The air gap design features an open air space that separates the runners from the hot engine oil resulting in a cooler, denser charge for more power.