The Chevrolet Performance 18-Degree V6 Aluminum Race Cylinder Head offers a significant improvement over conventional Chevrolet designs. They feature an 18 valve angle vs. the older 23 angle design with 43cc chambers. They also feature relocated valve centerlines, shallow combustion chambers, centrally located spark plugs and high-flow exhaust ports. The relocation of valve centerlines (.275" toward the intake manifold) minimizes shrouding at high lift and also allows the installation of larger valves (up to 2.20" diam. intake valves in some applications). These changes produce a substantial improvement in total airflow potential! Raised intake runners maintain the runner/port relationship with the revised 18-degree valve angle. This low-port version has excellent flow at low valve lifts due to their tall short-side radiuses and deep valve bowls. The shallow wedge-shaped combustion chambers allow builders to achieve high compression ratios with small piston domes. Spark plugs are .350" closer to the center bore than previous designs which improve flame travel across the chamber and reduce spark advance requirements. High-flow exhaust ports are .450" higher and .240" wider at exhaust manifold flange than previously. This minimizes turbulence in the runner and provides a smooth transition from the valve bowl to the header pipe for increased exhaust flow. Engineered to be the cylinder head for maximum effort V6 Competition!
Technical Notes:Sold without valve seats and valve guidesValves with .300" longer-than-stock stems are recommended for low-port V6/90-degree 180 heads400" longer -than -stock valves are recommended for high-port 18-degree headsAftermarket shaft-mounted rocker-arm assemblies and pushrods are requiredPiston domes and valve pockets must be matched to the revised combustion chamber designAftermarket head bolts with small diameter heads are recommended