The Edelbrock Victor CNC 12 6-Bolt Head for GM LS7 291cc/69cc Individual #77668 is designed for maximum effort naturally aspirated and boosted applications. It features .220 raised intake runners and .100 raised exhaust ports that provide a better line of sight into the cylinders and allow for an improved short turn. The raised intake runner design fits both stock and aftermarket LS7 intake manifolds and can be used with stock or aftermarket valve trains. The head utilizes the GM LS 6-bolt design making it compatible with the GM LSX block and all aftermarket iron or aluminum 6-bolt per cylinder LS race blocks. The 6-bolt design offers increased clamping capacity over the standard factory 4-bolt configuration and improves head gasket sealing – ideal for high compression naturally aspirated engines and high boost applications. Features include a 12-degree valve angle and fully CNC-machined ports for maximum airflow. CNC-machined runners and chambers as well as the .220 raised intake ports and 12-degree valve angle increase overall flow capability while a revised water jacket design enhances thermal conductivity and tunability. The manganese bronze valve guides withstand long wear with emphasis placed on holding precision tolerances on valve seat concentricity allowing the valves to seal securely which eliminates leak down and increases cylinder pressure during engine operation. Finally the .700 thick deck and .400 raised valve cover rail make this head ideal for maximum horsepower and high valve lift applications. All Edelbrock Victor CNC heads feature patented Clean Cast Technology(TM) a process that eliminates casting flaws and promotes a smoother internal surface finish for greater air and coolant flow. These benefits provide more power and increased cooling ability. Part #77668 is a bare head that features: 307cc runners 69cc chambers 2.250 intake/1.615 exhaust valves CI PM valve seats and no down nozzles.