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This cylinder head for competition small-block V8's represents a significant performance improvement over the Phase 6 head. The design moves the valve angle to 18º from its previous 23º. The valve centerlines are relocated .275" toward the intake manifold which positions the intake and exhaust valves on the centerline of the cylinder bore. This minimizes shrouding at high lift and also allows for the installation of larger valves (up to 2.20"). The valve centerlines are also shifted laterally to provide proper valve clearance with a variety of cylinder bore and valve head diameters. The intake runners are now raised, and floors of the intake ports are 1.220" above the deck surface. At valve lifts above .600", this configuration produces superior airflow. Shallow, wedge-shaped combustion chambers achieve high compression ratios with small piston domes. Spark plugs are closer to the center of the cylinder bore and shifted toward the top of the chamber, which improves flame across the chamber and reduces spark advance requirements. Exhaust flow is also increased because ports are .450" higher and .240" wider at the exhaust manifold flange than the Phase 6 Bow Tie head. The low-port configuration satisfies sanctioning body rules that require conventional port location, and are recommended for carbureted applications with limited hood clearance.
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