My friend is going to work on his FE heads some while he has them off. He wants to know what RPM range is unshrouding the valves good for? I don’t have a clue, thought I’d ask here. He’s concerned about hitting a seat, I mention install an old valve, but I don’t know if he’ll follow up on that. Thanks
Don't polish intakes. Try to cut a vertical 90 over the top seat angle as close to .100 wide as possible. Make the header flanges bigger than the exhaust ports by at least .125 or more. Make the intake manifold smaller than the intake port at least 1/16" overall. Those differences create a boundary layer in the reverse flow during cam overlap. If he can gouge out the port bigger than the seats on the intakes it creates a venturi effect, similar to a booster in a carb. Cone in toward the seats but go bigger above them. This should increase intake velocity at the best point in flow. Doing these things should literally be felt under foot. All the regular porting rules apply. The exhaust can benefit from a little polish but no need to go crazy. I used a carbide cutter when I did my nickel/iron Merlins. 2 guys I spoke with turned me down because they were iron. If you read this while looking at the job it will make better sense. Much of this was gleaned from the HP Books' "How to Hot Rod Small Block Chevy Engines" by Bill "Grumpy" Jenkins. And if you hear "...but it's a Ford..." just walk away. Yes, that was a sardonic statement. Good luck, can be a very rewarding experience.
The Jalopy Journal
