The AFR Emissions Legal (CARB EO #D-250-2 for engines up to 1994), 180cc intake port LT1 small block Chevy cylinder heads are available in the LT1 angle plug version only. These heads feature a 55cc to 65cc combustion chamber with a 64cc exhaust port and a 3/4” thick head deck (ideal for nitrous or blower applications). Standard valves are 2.020 intake and 1.600 exhaust with AFR’s hardened ductile iron interlocking valve seats. The exceptional flow characteristics, ideal operating range of idle to 6000 rpm (higher rpm ranges possible depending on combination of parts), 23º valve angle, and standard valve spacing make this the perfect street head for 350 cid to 383 cid engines and is specifically designed for 1992-95 Corvettes and 1993-97 Camaros. No special parts are required. Dual valve cover bolt pattern is standard. Exhaust port is raised .100 over GM L98 cylinder heads. Note: Hydraulic roller cams typically experience valve float at 6000-6200 rpm because of their fast ramp rates. AFR suggest you upgrade your springs to AFR part #8047, 1.530 O.D. with higher spring pressures and use our Patented “Hydra Rev Kit” to reduce chances of valve float associated with rpm 6200 or higher. Chevrolet LT1 - 180cc Stage 1 Bare Heads - 70cc Combustion Chambers, L98 Plug - Bare Heads