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Remember that the tight p-v clearance is (almost) never at TDC. The intake chases the piston down on the intake stroke, and the piston chases the exhaust valve up on the top of the exhaust stroke. You need to put your checker springs on the valves, degree the cam, and check the clearance at all around TDC to find the tight spot. .300 clearance at TDC doesn't mean squat.

You may be able to play with cam timing too. The combination I've got on my hemi doesn't let me run any more than 26 degrees on the cam. If I go any more the exhaust valves hit. I started at 28 and the v-p was nearly nothing. I found that if I backed the cam off to 26 everything came good (well good enough - it's still tight, but adequate). I figured 2 degrees off the cam was easier than fly cutting all of the pistons.

Perry

Good posts guys. I always check VP 4 before, TDC, and 4 after. Then if you want to play with it, you know you have V-P clearance without re-checking . Little joke here,....AH HAH!! Open chamber pistons and closed chamber heads!!!!!!!!!!!!!!!!!!!

Wow, $50 ea to flycut? Nuts.
Is the interference only the ridge between the valves Gary? You could hand message the piston tops..the ridge off, and CC them and be pretty close. I don't know how much comp you would lose,

My suggestion is pistons, but I can't figure why they are so crazy with .600 lift. could you post the cam specs and piston #?
Thanks Lippy

Heres the Most Simple way to Check your CLEARENCES!
Put the Heads on with a Set of Light Checking Springs,and of course your Cam,Crank and 1-Piston and Rod assembly.
You will need a Dial Caliper,or a mag Base Fixed Dial Indicator?
Roll the Motor around,with the Valve against the Piston?When it get the Closest measure it,you will usually find that its the closest at about 10*ATDC?Because like the fellow above posted the Valve is Chasing the Piston down the Cylinder!
Hope this simplifies things?
Also,you dont need a head gasket for this,you can just add the Thickness?
Later
G

more info . called a no of machine shops. and can get the fly cut resonable but they all said to a shop that it won't solve the clerance isue. it seems and i had forgot that with the sonny's dart heads i'm trying to use that the valves and the plugs are not in the normal location. it takes a little diffrent dome on the piston to clear. and with the stock heads and the pistons there not enough meat in the dome to go very far past 580 to 600 lift. the very reason they quit making them. a no of people with the manufactuers, took my calls and ansered all my questions with a lot of patience. i need to thank the fine people with crane , cv products and of corse dart industries for having a lot of patience. it could be worse i end up with a preaty good street motor but not a race motor. thanks to every one hear at draglist your no one!!! broke as usal gary b

Gary B.
Sorry about the clearance issues. Good you found the answer now though.
Gary S.

gary B, glad to hear you have a solution.