The Edelbrock #60057 Performer RPM Super Stock Cylinder Heads are designed for use with 1961-76 390-427-428 Ford applications. Edelbrock 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: • 428 Cobra Jet-sized valves promote excellent flow for streetable power • Rocker shaft stud kit #6009 provides better rocker shaft retention and is highly recommended for use with Edelbrock FE heads. It eliminates wearing of the threads and the possibility of bottoming the rocker shaft bolts in the head. • Match with Edelbrock head gasket sets. • 390 GT exhaust will not fit. • 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. • Recommended spark plugs are Champion RC12YC or equivalent 14mm x 3/4" reach with flat gasket seat. Deck thickness: 5/8".