For the ultimate small block Ford street car, youÍve got to use AFRÍs all new 165cc emissions legal aluminum cylinder heads. Unlike some aftermarket heads, AFRÍs Ford cylinder head (CARB EO #250-3) fits all your stock components; no special parts are required! With 1.900 intake valves, 1.600î exhaust valve, and combustion chamber volumes of 58cc or 61cc, and 69cc exhaust ports, AFRÍs new 165cc Ford aluminum head is perfect for 289 and 302 engines operating from idle to 6000 rpm. A 3/4î thick head deck makes the AFR head ideal for nitrous or blower applications. Will not accept rail rocker arms. Hardened push rods required with part numbers 1400 and 1402. Note: 1986 5.0L must have piston notched for clearance. Ford Small Block - 165cc CNC Street Ported Heads - 58cc Combustion Chambers, Stud Mount Rockers - Bare Heads