Hi Tommy, Was looking at MAP website head gaskets.
Dead soft or normal... What's the difference in softness? Meaning how much softer? Would be curious to know. If you heated a normal gasket bright red to anneal would it then be dead soft or not?
Or.... are they a different copper alloy?
Is it feasible the dead soft are too soft & allowing head to flex compressing gasket .0015"?
What does the gasket measure in many places? Is the head flexing down at the outside end bolts?
How much flex does it take to make a sealing difference in the valve seats?
New question. How thick is your head measured from top to head gasket surface using depth gage?
On the '69 Bonnie I did recently I measured. Uncut head original with known history. The '69 head is very similar to your '70.
OUTER: RF 2.781", RR 2.86", LF 2.780", LR 2.787"
INNER: RF 2.799", RR 2.793", LF 2.799", LR 2.790"
If you draw this out, clearly the head was machined at a slope with rear of head thinner. Yet the rocker box surface is flat so it must have been machined this way from new. Yet the outer bolts are opposite with the thicker in rear. In actual practice this head is working good with no leaks or seeps at box gaskets or head gaskets.
In prior discussions I have in my notes the nominal head thickness was 2.755" to box gasket surface. Another discussion put head thickness new at 2.785-2.795". Triumph gives no spec I could find. My TR7RV head was skimmed aprox. .009". I didn't measure it before, dumb I know, but was back in 70s. After it measures 2.775-2.785". Sloping about 45deg angle across head with thicker on front. Was this from the skim or factory?? I don't know. Again rocker box surface is flat. No leaks from this head either. Again old copper gaskets crushed only about .001" and are fairly flat in crush.
Lastly you said your crank balancer passed. Sorry to hear that. Indeed this is common these days. Did you balance the crank on this motor? What factor did you use? On the '69 with light flywheel used 68%. A huge improvement 60-70 mph. Prior it was awful at freeway speeds. I have much interest in balancing as well.