I am installing a Z head on my T engine. The engine has.040 over standard aluminum pistons. Checking the piston to head clearance with no head gasket I found .012 to .022 clearance on cylinders 1 & 4 respectively and .012 & .013 interference on # 2 & 3. Adding the head gasket at a nominal .065 will give clearance on all cylinders but is it enough? What is acceptable running clearance?
Agree with Frank. I have ran them closer without problems
I'm sure Frank and Mike are correct, but personally I'd remove material from 2 and 3 combustion chambers until there is no contact without a gasket. Prussian blue is good for this. Paint the piston top and see where it marks the chamber.
On performance orientated engines, the norm is to run pistons flush with the top of the block and then use the head gasket as the spacer....which generally runs between .039"-.060".
That being said, you are asking if your total .077" minimum (head gasket + piston to head clearance) is enough piston to head clearance. The answer is yes.
I would just make sure because the piston protrudes the block, that your minimum clearance is sufficient on all areas of the dome, IE nothing contacts the head without the head gasket.
Hope I explained that well enough.