Speedmaster PCE281.2171 Fits Chevy BBC 454 320cc 119cc Solid Roller Assembled Cylinder Heads

Assembly Specifications Max Lift: .650 Coil Bind: .925 Intake Install: 275lbs @ 2.1 Exhaust Install: 275lbs @ 2.1 Closed Sear Pressure: 210lbs Open Seat Pressure: 450lbs As with all Speedmaster cylinder heads, our Big Block Chevrolet heads are Gravity Die Cast . This casting process creates a much more uniform and robust cylinder head. With the increasingly large displacements becoming common, the need for more airflow is necessary. If you are looking to build a 400-500+hp engine, give our PCE281.1489 heads a try. They offer a smaller cross - section to increase the incoming air s velocity, resulting in great driveability, power and economy. On engines over 500hp, use the rectangle port PCE281.1488 heads. The mid-size cross section works well on engines under 540cu.in and under 7000RPM. If you are working on a larger, or higher RPM engine, step up to the CNC ported PCE281.1511 heads. The added volume of the PCE281.

• Assembled with the finest premium components to provide your engine with optimal airflow for maximum engine performance
• Improved power throughout the rpm range for greater throttle response and top-end horsepower