Will Gen vi heads fit on a Dart Big m sportsman block?i know physically they will.

All the new performance blocks are based on the Mark IV design.Can Gen Vi heads fit without water passage problems?Anyone.

This is a nice, basic guide to component compatibility and a good explanation of the cooling path differences between generations.

http://reviews.ebay.com/ebaymotors/B...00000001563647

Thanks Chris,learn't alot but it doesn't address the Merlin,World or Dart blocks.I have a feeling you are able to use Gen Vi heads with a special gasket to mate to these "aftermarket"blocks.Anybody else??

If the aftermarket blocks are based on the Gen IV, then the Gen VI heads will fit. How do I know?
I've been researching heads and gaskets for my Gen V blocks, so I am acutely aware of the compatibilities. The Gen VI block and head design were developed to be interchangeable with the Gen IV block and head water passages.

i have to dissagree as for compatability , the water passages have a greater chance of leaking due to a change on gen 5 block compared to a gen 4 after a little bookreading gen 4 and gen 5 are NOT interchangeable !! this strait out of the dennis moore book pg 9 it states as follows gen 5 changes in 1991 chevy introduced the gen 5 the casting core holes in the deck of the block were changed making them not interchangeable . if interchanged a mismatch will occur in the coolant passages and leak into the lifter valey !

Hi RR,
You've misunderstood the thread - the question is whether the Gen VI heads will fit on the Dart Block, not whether Gen IV heads will fit on Gen V blocks - which they won't without leaks or gaskets designed for the task.
I said the Gen VI heads would work on the Dart block, which is similar to the Gen IV in water passage layout.
Hope that helps with your dilema...

Some say it can be done but I've had first hand experience $$$ that is does not work well at all.

Two seasons ago we built an all new pair of 572's New GM Bow Tie blocks (Mark IV round coolant holes in deck) and went with a pair of GEN VI heads. We were well aware of the mismatch but we were told as long as the proper Fel Pro gasket was used it would work fine.
Guess what...as soon as block pressure went over 15 lbs, it would fill the block with water. We chased this problem for a month and eventually tore it down. Even though we flushed as best as possible, it still ruined everything.
Rebuilt everything and installed Dart Pro-1 heads (Mark IV holes) and all is fine.

Good luck,

Kurt

Most of the newer aftermarket heads are designed to be compatable with all Mark 4, Gen 5, Gen 6 blocks. I thought the Gen 6 heads could be used on all blocks but not the Gen 5's.

That's what we were told....but they (GM Gen VI) did not work.