p/v clearance threory-- bogus or not? what do you think?

[Jeff Chambers]

If you can't afford to replace the parts because you didn't check PV properly, then you can't afford to NOT do the PV check properly. If you've increased cam lift or duration, went to heads with a larger valve, gone to a thinner head gasket, or whatever, then the only sensible thing to do is to check it properly. From the way it sounds, you're planning on using your hydraulic lifters to check it as it is? WRONG! You need to make a solid lifter by removing the plungers from a few old lifters and turning them into solid lifters by flipping the internals or filling the lifter with washers. Otherwise, you'll collapse the lifter while you're trying to do the PV and won't get anywhere near the correct measurement.

TAKE THE TIME TO PULL A HEAD AND CHECK PV CLEARANCE CAREFULLY AND PROPERLY IF YOU'VE GOT ANY QUESTION AT ALL.

At most it'll cost you a few more hours and the cost of some new gaskets. But that's a bunch cheaper than new pushrods, lifters, valves, etc. that can be ruined by not doing it right.

When you check it, you want to maintain .100" clearance on the intake valve and .125" on the exhaust valve. Be sure to check for interference at the radius of the eyebrows as well since the valve may contact here before it runs out of room in the depth of the relief. You also want to maintain .040" clearance between the piston and the closed portion of the combustion chamber.