Sierra's 18-4485HP Cylinder Head Assembly is designed for use in GM Small Block 5.7L high performance engines (mid models). All GM cylinder heads utilize high performance screw-in rocker arm studs. Cylinder heads are new castings. Hardened steel exhaust seats, valve springs, valve locks and retainers. Key features include: CH350GA 5.7L Hybrid Pre-Vortec 217 style casting, 65cc combustion chamber, 176cc intake runner, 1.94 intake valve, 1.50 exhaust valve, TBI/Vortec style bolt pattern, and center bolt valve corner. Each Sierra product meets or exceeds the original equipment part it replaces. Attention: Replace in pairs.
