Absolute max refinish for head?

[Beaubo]

What is the absolute minimum thickness a head can be surfaced to, before valves and pistons come into contact? I am using a felpro gasket. Has anyone gone beyond the 5.16??? and been ok? If so what were your final grade measurements.

Just saw a post by BogusSVO about the minimum being 5.185 according to AERO. Has anyone gone below this without using a thicker head gasket?

 

[BlackDSMthingy]

If this is a 4g63 then you have to be careful not to make the oil supply teardrop too small or you're going to starve the top end of oil volume as well as having pre-detonation issues if you cut into the quench area of the combustion chambers too much. The heads have three "bullseye" looking spots in the casting which are typically .040" - .045" deep on a virgin head. These are indicators that help determine if a head has been previously planed. If the center of the bullseye has seen the cutting die, game over. Don't go further than that. Factory specs say that the head and the block both have an acceptable resurface limit of .008" each with a maximum of .050" away from flat across any point on the deck surface of the block or head. So if you can fit a .050" feeler between your straight edge and the block or head surface in any point and the resurface limit has been reached or will be reached or surpassed during planing, find another one. Your valves won't hit with normal cam phasing for a while past the service limit, but the most important thing is the oiling capacity for the top end and the detonation possibility you may encounter. Hope this helps...