Designed for competition 396-502 big-block Chevys. #2902 fits rectangular-port heads and #72902 features out-of-the-box pre-assembled direct port nitrous system ready to bolt on and go! Intake manifold #2904 fits large oval-port heads (1975 & earlier). These intakes are designed to optimize the flow characteristics of an 850 cfm standard flange carb. Features include extended runner dividers, smaller plenum chambers and unique runner design for better 60 foot times and max power from 3500 to 7500 rpm. These manifolds are especially suited to 502 c.i.d. and smaller competition engines. This manifold is cast with 3/8" more material in the corners of the ports for a final radius of 3/4". This extra material allows for custom port matching for use with various cylinder head applications. It is designed to be matched with our Edelbrock/Musi Victor 24° Pro-Port CNC heads #61419 or #61409 for 950+ hp out-of-the-box potential! Victor Jr. 454-R #2902 will fit Edelbrock Victor race heads #77609 and Victor 24° #77409, #77459, #77429, #77479 and #77489. CARB RECOMMENDATIONS: Use appropriate racing Carburetor. THROTTLE BODY RECOMMENDATIONS: Use #3878 4V series or #3849 EFI elbow and #3869 90mm throttle body. THROTTLE BODY RECOMMENDATIONS: Use #3878 4V series or #3849 EFI elbow and #3869 90mm throttle body.