Engine Cylinder HeadThe Edelbrock #61599 Performer Pontiac Cylinder Head utilize a D Port exhaust port configuration for use with standard D port exhaust systems. They are designed for 1962 79 389, 400, 421, 428 and 455 c. i. d. V8 Pontiac engines with a 4. 060" or larger bore. They feature optimized oil return passages for increased oil flow. The spark plug has been relocated closer to the exhaust valve for improved performance. This head is cast with extra thick port