Edelbrock Part # 61255 Victor Jr. 23° 220 cylinder heads are designed for small-block Chevy 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.Cylinder Head Specifications: • Finish: Satin • Designed for use with Hydraulic Roller camshafts • Combustion chamber volume: 64cc • Intake runner volume: 220cc • Exhaust runner volume: 85cc • 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: .630" • Rocker stud: 7/16" • Guide plate: Hardened steel • Pushrod diameter: 5/16" • Valve angle: 23° • Exhaust port location: Raised .300" • Spark plug fitment: 14mm x .750 reach, gasket seat