Food for thought in the question of the high compression ratio problem. I recall that it was mentioned that the
head was rebuilt prior to this problem of pinging occurring.
What can happen if the valve seats and / or valves are replaced, the may sit a little “prouder”, or further into the
combustion chamber than a stock setting.The valve seats may be sitting higher in the head, moving the valves into
the combustion chamber. In the case of valve replacement, if after market or incorrect valves have been used,
there may be the difference of a dished valve head surface replaced with a valve with a flat valve head surface.
This, or both circumstances would reduce the effective combustion chamber volume and increase the
compression ratio. I would check the compression and see if it exceeds the new engine values, and if so, it is
either an over machined head or the valves. If the compression is not higher than the stock value, look for a lean
fuel problem or improper timing possibly induced during the new heads installation.
If the compression is in fact higher, the head comes off any way, but first, “CC” the combustion chambers before
attempting the thicker head gasket.