[gtofreek]

Here are the Edelbrock D-port heads going on it. They have been ported to 320 CFM or so.



Valves weren't sealing very good anymore.





These heads were run with some nitrous for a bit. It really distorted the valves and the head deck surface. I have a video of the valves, but haven't downloaded it yet either, so I will post a link when I do.

If you look closely at this valve, you can see where it cleaned in 2 spots 180° apart, and didn't clean in 2 spots. They were not bent, but warped.





The first light pass just cleaned a couple spots at each end.





The next .004" pass revealed the center of the head being heat distorted where the exhaust heat is concentrated.







This is a good shot. It shows the raised area on the inside of the dowel pin. This is caused from the head being installed on an iron block. When the engine gets heated up, the head grow more than the block, which in turn, pushes on the dowel pin forcing a bulge in the aluminum. This expansion has actually been known to sheer the dowel pins in NASCAR engines that run at higher than normal temps. Because of it, they started slotting the dowel pin holes so the heads could grow without binding.



Here's the heads all finished up.