I previously had a 305 and bought the vortec heads and milled them .030", well, I got the gmpp 350 that came with vortec heads and had 9.0 to 1 compression. I went ahead and put a new cam in so I put the milled heads on also. The cam is 224/230 , 470/480, I had a valve job and got better springs and did use normal thickness head gaskets. I figured since the engine was 9.0, the milled vortec's would put it around 9.5-9.7 to 1 compression. You all will cringe, but I just put them on without checking clearances. Well, I'm going to pull them off here before long and probably get 2.02/1.60 valves put in them. When I re-assemble, I figure I will use the clay method and was wondering the "exact" procedure for this and what clearance I should look for ?? Thanks guys

 

JJ,

I'd be scared with much less than 0.040" clearance.

The procedure I'd use (whether it's correct or not) would be to mold a piece of clay into the valve reliefs in the piston top, set the head in place with a used (already compressed) gasket, snug up a few head bolts by hand, and install a couple of push rods and rockers. Crank the engine over slowly at least two revs, then remove the head. check the thickness of the clay where the valves made their impressions.

Forty thousandths of float is not unheard of at higher RPMs, and you don't want to the valves to deliver the "kiss of death" at 6,800. You'd probably never find all the pieces.

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Later,
Vader
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thanks, I'll be sure to do that