The Edelbrock #60919 Performer RPM NHRA Stock/Super Stock Bare cylinder heads are designed for 1961-79 Chrysler 361-440 c.i.d. Wedge 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. • Cylinder heads flow 291 cfm on the intake and 217 cfm on the exhaust at .600" lift • Angled spark plugs for superior combustion • 88cc chambers are machined .100" for clearance with quench dome style pistons • For headers, contact TTI (951) 371-4878. • Vacuum advance distributor may not clear cylinder head. • Deck thickness: 5/8" • Pushrod diameter: 3/8"