The Edelbrock Performer RPM Rectangular Port Aluminum Cylinder Heads have specially designed intake and exhaust ports for increased flow and velocity over standard big-block heads. These heads feature a highly-efficient 118cc open-style combustion chamber for maximum performance. It is engineered with high-velocity 315cc long and 300cc short intake runners. They are designed for street and high-performance vehicles, operating from 2, 500-7, 000 RPM. The stainless steel, hardened tip 2. 19'' intake and 1. 88'' exhaust valves have smaller-than-stock 11/32'' valve stems to promote excellent flow and lighter valve weight. The deck surface and water jackets were specially designed to work with all big-block engines. The volume of the intake runner is 315cc and the exhaust runner is 300cc. The heads include top-quality ARP rocker studs, bronze guides and hardened, ductile iron valve seats.