[Alan Roehrich]

Aubrey, so long as without lash, the clearance between the intake valve and the piston is greater than the clearance between the piston and the head, you have plenty. In other words, if you have 0.055" piston to valve, and 0.045" piston to head, you're good.

On the exhaust, you need about 0.075". The piston chases the exhaust valve shut, and the exhaust valves are known for bouncing on the seat. Yes, they'll show a light spot in the carbon on the face of the valve and the top of the piston. If you want to go fast, that's what you do.

Yes Aubrey, you need at least 250 on the seat, and 525 open, you need the same pressure, and the same parts, that we run on a 396/375, or a 427/425.

You really need about the same lobes as we run, you're allowed 0.507" and 0.519", you can run the same lobes, and use pushrod length to kill off some lift on the intake.

I'd take a wild guess and say a good starting point for you would be 254/266/108, in at 106. You might try a 107 LSA, in at 105, to move the power band down.

The Ferrea valves I run in a 427/425 iron head should work, they'll "adjust" the diameter.