This intake manifold for big-block Chevy is a variation of the Victor 454-R manifold with a 3/4" radius in the ports, producing a port exit compatible with current large oval port heads such as the Edelbrock Victor 24° CNC head. This manifold delivers excellent on-track performance on 502 c.i.d. and smaller engines. It can be ported to fit a wider variety of cylinder head shapes and locations, making it especially suitable for use with custom CNC ported heads.