The smallest intake volume runners in our line-up, but don’t let size fool you. Our 305cc “As Cast” with CNC bowl blend or fully CNC ported 315cc aluminum cylinder heads will provide you with flow numbers most medium sized 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. Their application should be focused on smaller cubic inch Big Blocks (396-502), 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 555 CID, where low rpm power and drivability are a factor. The 315 version is extremely versatile with its incredibly strong low and midlift airflow figures as well as peak numbers approaching the 400 CFM mark. Either one of these two cylinder heads would be a great choice if your looking for big torque, strong low rpm performance, and still have good rpm capabilities. Both the 305cc and the 315cc come 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 119 cc’s on the 305 “As Cast” pieces, while our fully CNC ported 315cc version comes with a 121cc chamber. Both are available with an optional 114cc combustion chamber as well. Chevrolet Big Block - 305cc Competition Package Ported Heads, Assembled - 121cc Combustion Chambers