The Edelbrock part # 77579 Small Block Chevy Victor Jr. 215cc cylinder head is an affordable version that will still allow for maximum power when used in competition and ultra high-performance street applications. This cyinder head has the potential of 530-580 hp out-of-the-box, for a cost effective, race-winning set-up. These cylinder heads feature angled spark plug holes and accept standard 23° valvetrain hardware. The 77579 cylinder heads have a 64cc combustion chamber and come with valves only so you can add your own springs. The 64cc chambers yield about 12.5:1 compression with a 12cc domed piston in a 350 V8. INSTALLATION NOTE: Check cam manufacturer's specs for compatibility with valve springs for spring rates. Match with Edelbrock head gasket sets. Use Head Bolt Kits for easy installation. These heads require the use of a 14mm x 3/4" reach, flat gasket spark plug with a heat range appropriate to your application. Deck thickness: 9/16", rocker stud diameter: 3/8", pushrod diameter: 7/16" (width of slot in guide plate).