Originally Posted by rusty70f100
They're full of so much bovine excrement...
The 360 pistons in a 390 will NOT stick above the deck, you'll have .012" deck clearance (I measured mine when I built my 390). They're just the right deck height. Plus, they will NOT give you 10.6:1 compression. If you figure 10cc valve reliefs, 72cc chambers, and .012" deck clearance, in a .030" overbored 390, with a .043" thick fel-pro permatorque head gasket, you'll get 9.511:1 compression. That's not too bad IMO.
The compression height of truck 390 pistons is 1.680"
The compression height of 360 pistons is 1.776"
The difference is .096"
They've got their numbers wrong.
Problem with the measurements on decks is that this is all on paper, untill you put the slugs in the cylinder, you don't know. I think they have to CTA... I have 360's in mine and they extend past the top of the deck, if I recall correctly, about .010". The diffference was made up by using a copper shim with the regular FelPro.
--Mike