Edelbrock part 61019 Performer RPM complete cylinder head is designed for 1955 - 86 Small - Block Chevy applications that are 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 and valve springs. Cylinder Head Specifications - Exhaust port location Stock - Spark plug fitment 14mm x 34 reach, gasket seat