skullandbones

I got the GT40P heads in a great engine deal. At the time, I had no idea if I would be able to use them. So a little more research told me that they were considered pretty good performers. One thing was the change Ford made in the spark plug location (more centrally located in the cylinder). So I port matched the runners to the intake and exhaust manifolds. I started by scribing a line around each port with a scratch awl. This was easy to see when metal started flying. Like I said before, the intake runners were a peice of cake in that there was only a 1.5 or 2 mm difference. So I gently shaped the runner to match the dimensions of the intake and didn't worry about taking metal off all the way into the valve area. It really looked like a continuation of the intake runner after I was done. The exhaust ports were totally different. The shaping of the port to fit the exhaust tube only created a very drastic change in a short distance. It would have worked without doing anything but I got greedy so I decided to spend some time "porting" the runner. I had heard in the literature that the heads had a lot of "meat" on them and that I shouldn't worry tot much about getting into a water jacket. My initial thought was that the exhaust ports looked completely mismatched with the intakes. It wasn't only the size but two other things bothered me. The valve stem support area was very large (sort of in the middle of the passage). The other obsticle was a vertical corner (90 degree) instead of a curved passage. Long story short: I used a 6 inch inside caliper to shape the passage and change the valve stem area until the passage was pretty uniform from valve to exhaust port. Even my Chevy lovin' machinist was impressed with their look. The next thing was to have the machinist use the valve springs from the E7 heads (came with engine) because they were matched to the stage one cam (B cam equiv). The heads had to be decked a little (0.10, I think). I used the new exhaust valves and the GT40P intakes. All in all, they looked pretty good for my plan. So for about $152, I got a definite upgrade for my 300 hp crate engine.