High flowing AFR 227cc intake port small block Chevy angle plug aluminum cylinder heads are available in three stages of performance. The Race Ready version features 100% CNC ported intakes while the higher flowing Competition version features 100% CNC ported intakes with greater detail. Both come with 100% CNC ported 76cc combustion chambers and 80cc exhaust ports with a 3/4î thick cylinder head deck (ideal for nitrous or blower applications). In addition we also offer the ñas castî Stage 1 heads for 227cc performance on a budget. Standard valves are 2.100 intake and 1.600 exhaust with AFRÍs hardened ductile iron interlocking valve seats. The 227 has 60/40 valve spacing and piston valve pockets should be checked. The exceptional flow characteristics and 23_ valve angle make this the perfect cylinder head for 350 to 434 cid engines in drag cars, sprint cars, and late model oval trackers operating from 4500 rpm and up. The 227cc cylinder heads are available in either standard or spread port exhaust. AFR offset stud girdles are the only special parts required. Some applications require shaft mount rockers for durability and reliability of valve train components. Not recommended for street use, unless shaft mount rocker is used. The exhaust port is raised .400 over GM L-98 cylinder head. Note: These cylinder heads are specifically design for 1992-95 Corvettes and 1993-97 Camaros LT-1 and LT-4 engines using the GM LT-4 or equivalent manifold. Chevrolet LT4 - 227cc Race Ready CNC Strip Ported Cylinder Heads - 55cc-65cc Combustion Chambers, LT4 Plug - Fully Assembled