All the technology in the world isn't worth squat if you start out with a poor set of heads. As such, the first step in the CNC process is some good old-fashioned hand porting. With symmetrical heads, where every port and chamber from cylinder to cylinder is the same, only one set of ports needs to be designed by hand. With siamesed heads, such as 23-degree small-block Chevy castings, two sets of ports must be designed. SAM students and instructors coaxed 460 cfm out of the prototype port and chamber on these Edelbrock Victor LS-R heads.