The Edelbrock #61625 Performer RPM cylinder heads are designed for use with 351C, 351M & 400M Ford engine applications. The Edelbrock #61625 Performer RPM heads are perfect for street performance, daily drivers, street rods and muscle cars where seat-of-the-pants performance is needed. These cylinder heads deliver great throttle response and power from 1500 to 6500 rpm. They also feature the highest quality intake and exhaust valves and valve springs. For use on pre-pollution controlled vehicles only.