The Edelbrock #60767 Performer RPM NHRA Stock/Super Stock Bare cylinder heads are designed for use with non-emission 1968-91 Chrysler 318-340-360 c.i.d. engine applications. These cylinder heads deliver great throttle response and power from 1500 to 6500 rpm. Cast and heat treated at the Edelbrock Foundry and machined at Edelbrock's manufacturing facility in the USA, Edelbrock heads are the best in quality and performance. All Edelbrock Cylinder Heads are designed from scratch using the latest in computer technology by our own highly skilled engineer's. Using highly efficient ports and state-of-the-art combustion chamber shapes, Edelbrock cylinder heads offer improved performance throughout the rpm range for great throttle response and top-end horsepower. Top-quality features include threaded inserts in rocker stud and exhaust bolt holes for superior strength and durability, and manganese-bronze valve guides with ductile iron valve seats. These are features that some other companies don't include!INSTALLATION NOTE: • Bare heads will have valve guides and seats installed, but will require final sizing and a valve job to match the valves you will be using. • Delivers outstanding performance in non-emission 1967-91 Chrysler 318-340-360 c.i.d. engines • Make 417 horsepower and 397 ft-lbs. of torque on pump gas with an Edelbrock Performer RPM intake manifold and matching camshaft • The special valvetrain in the 1970 340 T/A is not compatible with these cylinder heads. Match with Edelbrock head gasket sets. • Recommended spark plugs are Champion RC12YC or equivalent 14mm x 3/4" reach with flat gasket seat. • Deck thickness: 5/8" • Pushrod diameter: 5/16".