DonMan

I know we`ve done this subject before, but even after searching the archives, I didn`t get a clear answer to my question.
I`ve got a Gen VI 454 block. Can I use Mark IV ( cast #188 ) heads. I read were aftermarket Mark IV style heads (Merlin, etc..) can be used after punching hole on gasket. I just didn`t read that anyone has used a factory GM Mark IV head on the Gen VI block.
I think FelPro lists possible gasket/head combos in their performance catalog, but I can`t remember.....

jspeeddemon

Block have round or tear drop style water passage transfer holes?
You can plug the front holes with pipe thread and run Mk 4 head gasket like a 1017-1, if you have round transfer slots, then it is just like a Mk 4.

bajalome

Donman,
The Gen IV heads will work on the Gen VI 454 block according to chevrolet. They changed the block in 91 to the Gen V and when they did that they increased the size of the water jacket at the top of the deck, as a result the coolant could seep out into the lifter valley. So the heads will not work on a Gen V. However in 96 they came out with the Gen VI block and made the changes to accomodate the Gen IV heads. I just recalled this info from the Dennis Moore performance book. Wish I could remember where I put that book. Hope this helps.