The Edelbrock #61779 Performer RPM cylinder heads are designed for use with 1992 & later 5.2L (318 c.i.d.) and 1993 & later 5.9L (360 c.i.d.) Chrysler Magnum style V8 applications. The Edelbrock #61779 Performer RPM heads are perfect for street performance, daily drivers, street rods and muscle cars where seat-of-the-pants performance is needed. These cylinder heads deliver great throttle response and power from 1500 to 6500 rpm. They also feature the highest quality intake and exhaust valves and valve springs. For use on pre-pollution controlled vehicles only.INSTALLATION NOTE: • EQUIPPED WITH SPRINGS FOR USE IN HYDRAULIC FLAT TAPPET CAMSHAFT APPLICATIONS • Match with the Edelbrock RPM Air-Gap Magnum manifold #7577 • Cylinder heads exhaust flanges in stock location to allow use of stock exhaust if desired • Accepts small-block Chevy adjustable 1.6 ratio rockers and classic valve covers #4177 and #41773 • Requires hardened pushrods, #9638. • 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" • Rocker stud diameter: 3/8" • Pushrod diameter: 5/16" (width of slot in guide plate).