Interesting comments about the overheating - it makes sense.

What I recall from the last time that the matter of the head thickness was raised I can comment as follows;

The minimum thickness does not relate to the valve piston clearance (assuming stf cams etc). This I can absolutely assure you as I have in the past run below the proposed minimum thickness with no such issue in this regard.

The wisdom is that it actually relates to the amount of material around the valve seats. Specifically on the inlet side (i believe) it gets dangerously thin, which theoretically can allow the valve seat to become dislodged.

In addition, I believe that it alters the squish area of the cylinder head, which can adversely affect the combustion.


JJ