The smallest big block Chevy rectangle port intake volume runners in AFR's line-up, but don't let size fool you. This partially ported 305cc cylinder head features a CNC bowl & chamber blend that will provide you with flow numbers most medium sized cylinder heads (and some larger) can only dream about. This line was designed to optimize low and mid-lift airflow, while still generating impressive peak figures. The application should be focused on smaller cubic inch Big Blocks (396-502ci), with a primary operating range of 2500-6800 rpm's (this range is an average and will vary with engine displacement as well as component selection). These heads should also be given strong consideration in larger street driven or marine applications up to 555ci, where low rpm power and drivability are a factor. AFR 305cc cylinder heads would be a great choice if your looking for big torque, strong low rpm performance, and still have good rpm capabilities. The 305cc comes standard with AFR's trademark .750'' thick head deck, reinforced rocker stud bosses, and are equipped with premium one-piece stainless steel 2.250'' intake valves and 1.880'' exhaust valves. Standard combustion chamber volume is 117cc's on the 305cc partially ported heads. Take note the higher flowing exhaust ports and bolt pattern are raised .375 (3/8'') over stock location, this rarely affects header or chassis fitment. .
Installation Notes: Optional stud girdle required for 2° rolled valve angles and 1'' longer head bolt needed on four bottom exhaust bolt holes. Longer pushrods may also be required.305cc Rectangle Port Magnum Cylinder Head Features: