Chapman is one of the guys who figured this stuff out 20 years ago. If you go dig around the internet looking for articles on Chapman you'll find a bunch of cool stuff. He was using CNC porting to win NASCAR races 15 years ago. I think he was one of the first guys to get raw castings from the head mfgs and then machine the entire port. I don't think they did much if any hand finish work on Chapman heads.
Chapman is the last set of heads I bought... very nice CNC
stuff and I still touched them up.. only due to the spacing
of the cuts... I didnt get carried away but did pick up 3 cfm...
that was on the same machine
