valve clearance

I am putting engine back together & I do not have any valve clearance on exhaust valves. I was going to cut reliefs deeper in pistons this weakend but before I do I want to make sure it is necessary. I have a custom ground cam that came in engine that was running before it broke a rod & do not know anything about specs. Can I advance or retard cam timing to get more clearace or what should I do? old pistons did not even have valve reliefs in them & thats what is making me think I am screwing up somewhere.

What were the old pistons? what are the new pistons? How did you check clearence?

0.125" is rule of thumb for piston to valve clearance on the exhaust side.

Also need to know how you checked your piston to vlave clearance: Method and procedure.

OLD PISTONS WERE JE DISHED & NEW ARE JE FLAT TOPS & I WAS TRYING TO CHECK WITH CLAY, THE VALVE WILL HIT THE PISTON & LOCK UP. I AM CHECKING WITHOUT HEAD GASKET INSTALLED.

#1 Check it with a used head gasket installed. That's the #1 rule and you will be amazed at how much difference it makes.

#2 If your intake valve to piston clearance is not enough, then retarding the cam will help and advancing the cam will hurt.

#3 If your exhaust valve to piston clearance is not enough, the advancing the cam will help, and retarding the cam will hurt.

Hope this helps,
Charlie Evans

I will try it with head gasket installed, I was thinking if it did not have enough clearance without head gasket & only adding another .046 clearance with head gasket it would still not be enough. Thanks for the help.

Head gasket installed and proper valve lash adjustment .

I think I may have figured the problem with the exhaust valve clearance. I made a notch in the piston using my head as a guide & the new notch is about a 1/16 of an inch below the existing notch. The pistons may be for relocated valves on the newer aluminum heads, just a guess. They are je 17024 & je does not specify on there site.