The KB 243 specs state that it should be .018" over the top of the deck.
However, the small pop up on the top of the piston is .030" tall (from the
shoulder to the top of the piston). So, in order for the top of the piston
to be .018" over the deck, the shoulder of the piston is .012" below the
deck. My pistons do measure at .018" over the deck (to the tops) as
specified, so the piston shoulder sits .012' below the deck surface.
My question then is what to put into the compression calculator? Is the
.012" to the shoulder of the piston taken into account in the 6cc piston
head volume, or do I need to enter that separately?
The specs on my 340 are:
bore: 4.1"
stroke: 3.31"
cylinder head volume: 64cc
head gasket thickness: .040"
gasket bore: 4.125"
with KB 243's measuring .018" above the deck at the top of the piston.