Edelbrock introduces its new E-Street 15-degree LS3 69cc cylinder heads (PN 77620) as a premium replacement option, ensuring great power on any high-performance or stock GM LS3 engine build. These heads offer the best performance value of any aftermarket GM LS3 head. Sold in pairs and assembled with premium COMP Cams valve train components, these LS3 heads are engineered with the same architecture as the factory head, and all stock components will fit without issue. The assembled heads feature Beehive(TM) Valve Springs, chromoly steel retainers, heavy-duty stainless-steel valves, and top-quality valve seals – all inspected and assembled by qualified Edelbrock technicians. The intake valve size is 2.165 while the exhaust is 1.590 . The Beehive Valve Springs allow up to .570 lift camshafts, ideal for many mild to hot camshaft grinds. Edelbrock E-Street 15-degree LS3 cylinder heads are manufactured with premium aluminum alloy, machined to the industry's tightest tolerances. They feature manganese bronze valve guides for extended wear, with particular emphasis placed on holding precision tolerances on valve seat concentricity. This allows the valves to seal securely, eliminating any leak-down and increasing cylinder pressures during engine operation. All Edelbrock cylinder heads feature patented Clean Cast Technology(TM) , a revolutionary 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 right out of the box. A unique dual spark-plug-pocket design allows you to use the factory-style tapered-seat spark plugs or gasket-seat spark plugs available in wider heat ranges for maximum tunability.