Performer RPM rectangular-port 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. Engineered with high-velocity 315cc long and 300cc short intake runners, they are designed for street/high-performance big-block Chevys operating from 3500-7000 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 Chevrolet engine blocks. Heads include top-quality ARP rocker studs, bronze guides and hardened, ductile iron valve seats. Note: The spark plug position and combustion chamber have been optimized for use with flat top or low dome pistons and will interfere with high compression, high dome pistons designed for stock Chevy open chamber heads. If a high compression domed piston is to be used, purchase a piston designed for use with the #350-6055 cylinder head.
Tech Tip: To gain more spark plug clearance, Edelbrock recommends using Champion RC Series plugs such as the RC12YC (P/N 192-49776). They are 0.230'' shorter than a conventional spark plug and have a 5/8'' hex for easier access.