testtube

I just had 2.02 valves put in my stock lt1 heads. the edges of the intake valves hang just a bit below the surface of the heads. Will this give me clearance issues between the valves and stock pistons when the valves open? If so, what would be the best way to avoid or fix the problem? I have the stock cam in the engine now, but id like to go with a .510 lift cam. You guys think this will work? thanks for your help.

hotrod_chevyz

You may have to get some different pistons. In that situation i think most people buy flat forged pistons W/O valve reliefs, and then have them machined for valve clearance.

If you dont want to have to go to those extremes depending on what pistons you currently have you might be able to get a carbide cutter and mod the pistons to make space for bigger valves and high lift.

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testtube

how can i tell if im going to have clearance problems? the guy at the machine shop said something about a clay mock up. but I honestly have no idea what he means or how to do it.

Morley

You get a lump of clay and put it on a piston about 1/4" thick. Bolt the head down with the same gasket you intend to use on final install. Put rocker arms on just for the cylinder you put the clay in. Adjust them properly then slowly rotate the engine so that the valves go fully open. If you get a valve open and feel resistance, stop. Remove the head and look at the clay. If the valve made an impression that goes down to the piston...you gots problems. If the impressions left by the valves don't go all the way to the piston, measure how thick the clay is at the deepest point in the depressions. I believe you are looking for at least .060" to allow for the thermal expansion and growth of the valves and pistons. If that all checks good, do the check on another cylinder on the same bank, then do it on 2 cylinders on the other bank.