Edelbrock Single Marine BBC Rect Port Head w/ ValvesThe Edelbrock #61559 Performer RPM Marine Duty cylinder head is designed for use with Rectangular Port Big Block Chevy Marine applications. The Edelbrock #61559 Performer RPM head is perfect for street performance, daily drivers, street rods and muscle cars where seat of the pants performance is needed. This cylinder head delivers great throttle response and power from 1500 to 6500 rpm. They also feature the highest quality intake and exhaust valves