Designed for high-performance non-emission 1965-76 Oldsmobile 400, 425 and 455 cubic-inch engines with Torker 455 manifold #350-2730. This head features an improved 77cc combustion chamber design that increases the quench area for a more efficient burn. This results in outstanding horsepower and torque. These complete heads are assembled and ready-to-run with stainless steel 2.072'' intake valves and 1.680'' exhaust valves, hardened ductile iron valve seats and phosphor bronze guides. The valvetrain has been upgraded from the factory pedestal-mount system to a 7/16'' screw-in stud and 3/8'' pushrod-slot guideplate for increased valvetrain stability. The high-velocity, factory location ports feature 188cc intake runners and 106cc raised-floor exhaust runners for substantially improved flow and increased power. Head bolt holes are drilled for the stock 7/16'' bolts, but can be easily modified for 1/2'' bolts or studs by drilling the 1/2'' counterbore. Aftermarket rocker arms and hardened pushrods are required for installation. These heads will fit 350-403 Oldsmobiles with Edelbrock manifold #350-7111 only (port matching required). Use head bolt kit #350-8558.