Intended for high output, large cubic inch racing engines with 4.84" bore spacing, this head is an improvement over existing 18° designs, such as the Big Chief & Big Duke. The casting is made from A-356 aluminum and is Hot Isostatic Pressing processed (HIP) for superior strength, durability, dimensional stability and exceptional finish quality. These cylinder heads feature CNC ported intake ports and a raised exhaust runner design for improved flow efficiency. Chambers are fully CNC ported and extra material is included in the deck to allow fine tuning of the combustion chamber design, if desired. Edelbrock and Pat Musi worked with Jesel to improve the valvetrain geometry, delivering Pro-Stock level technology on engines up to 10,000 rpm. Jesel's shaft-mounted system, #KPS-387154, is made from lightweight 7000 series aluminum and features a one-piece stand design that pairs the intake and exhaust stands for improved valvetrain stability. The intake features a 1.820" long fulcrum and is available in 1.60:1 - 1.95:1 rocker ratios; the exhaust features a 2.000" long fulcrum and available in 1.60:1 - 2.00:1 rocker ratios. Requires Edelbrock valve covers #4259. Match with Edelbrock Victor CNC Series manifolds #28003 and #28005. Pro-Port version available for custom porting.