Edelbrock Victor Jr. 23° 220 cylinder heads are an affordable option that delivers maximum power in high-performance street and entry-level competition engines. Its 64cc combustion chamber yields around 10:1 compression ratio in a typical flat-top application and about 12.5:1 when used with some of the most common 12cc dome pistons. One of the key features of the Victor Jr. 23° 220 cylinder heads is the CNC machined chambers and bowls, which result in consistency and improved performance. They also feature angled spark plug holes and maintain the stock 23° valve angle as well as the intake flange bolt pattern for use with 1986 and earlier intake manifolds. All of this allows these cylinder heads to deliver 530-580 hp potential right-out-of-the-box, making them ideal for a budget minded engine build desiring a high quality cylinder head that still uses a stud and guide plate rocker system. Bare heads will have valve guides and seats installed, but will require final sizing and a valve job to match the valves to be used. ** Combustion chamber volume: 64cc; Intake runner volume: 220cc; Exhaust runner volume: 85cc; Intake valve diameter: 2.10"; Intake valve diameter: 2.10"; Exhaust valve diameter: 1.60"; Valve stem diameter: 5/16"; Valve guides: Manganese bronze; Deck thickness: 11/16"; Valve spring diameter: 1.55"; Valve spring maximum lift: 0.700"; Rocker stud: 7/16"; Guideplate: Hardended steel; Pushrod diameter: 5/16"; Valve angle: 23°; Exhaust port location: Raised .300"; Spark plug fitment: 14mm x 3/4 reach, gasket seat. ** INSTALLATION NOTE: Check cam manufacturers specs for compatibility with valve springs for spring rates. Match with Edelbrock head gasket sets or use Fel-Pro intake gasket #1206 and Fel-Pro exhaust gasket #1405. Requires hardened pushrods. Use Head Bolt Kits for easy installation. These heads require the use of a 14mm x 3/4in. reach, flat gasket spark plug with a heat range appropriate to your application.