The Original... Our Proven, Race-Winning Air-Gap Design in a Dual-Plane Manifold. Designed for 1955-86 262-400 c.i.d. Chevrolet V8s, the award-winning RPM Air-Gap 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. Includes rear water outlets, two distributor clamp locations and nitrous bosses. Accepts all 1976 and later alternator and A/C brackets for the street. The heater outlet boss is angled for proper fit over the valve cover. The temp sensor boss clears all waternecks. For square-bore carburetors only. No provision for exhaust-heated chokes and no exhaust crossover. Not for 1987 and later cast iron heads.