How is this done? I am installing new aluminum heads, and I thought if you put the head on with the gasket in place, it would make an impression on the head (and the head would need to be surfaced after that)....

I understand the clay on the piston, set everything up, lash the valve, rotate the engine, pull it apart, measure the thinnest part of the clay=the clearance. (what kind of specs am I looking for on this, btw)

But I dont know how to set this up accurately without damaging head surface on my brand new AFR heads.

Anyone have any ideas? I'm clueless, my first time doing this. Thanks for your help!!!

[This message has been edited by black73 (edited December 09, 2004).]

I just did mine the other day. I bolted the head on without a gasket and just snugged it down. I used checking springs and a dial indicator. With the degree wheel on I checked both valves from around 15* BTDC to 15* atdc. I think you should have about .100 clearance on both for a minimum. The experts here can give you the best advice.I then added in my gasket thickness for a total clearance

Hope its right
Sheesh, I just noticed you were using clay. I think you clean the top of the piston and lay a layer of clay down so it sticks and then lightly oil the valves so they don't stick to the clay. Set the head on and bolt it down and then turn the engine over at least 2 full revolutions. Remove the head and measure the thinnest point on the clay where the valves hit. You might be able to do this with out the head gasket also then add in its compressed thickness to get max. clearance

Jerry

[This message has been edited by JBE (edited December 09, 2004).]

how do you do the method where you dont use clay?

If you go to Comp Cams or Crane website the procedure is shown along with cam degreeing

Hope this helps

Jerry

Did mine just like JBE

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1972 Camaro 350 factory heads 1.94/1.5 street driven full interior
93 octane everything works 7.59
89.54 mph
Never owned a trailer never will!

Using the checking springs and a dial indicator is the best way. Be sure and check clearance on the exhaust and Intake from at least 10-20° BTDC to at least 10-20° ATDC. The tightest clearance rarely happens at TDS. Just keep in mind the piston chases the intake valve closed, and the intake valve chases the piston down the cylinder. Agressive cams can close the gap in a HURRY.

There is still merrit to using clay (in addition to a dial indicator). If your running a large valve head, radial clearance in the valve relief can't be checked any other way. For clearance you want AT LEAST 0.010" for the intakes and AT LEAST 0.020" for the exhaust valves. That is ABSOLUTE MINIMUM and assumes no valve float or any 'hiccups' of any sort. A safer clearance is 0.080" Intakes and 0.100" exhaust.

So far I have been able to get away with about .090 inch on both intake and exhaust but I know my engine builder cringes everytime I hit the rev limiter.......

ok. Thanks for your help guys!