[Elarson]

Originally Posted by 60man

OK..Speaking of dissimilar metals....which combo would tend to seal better....a aluminum block & heads ....or a iron block & aluminum heads ??? Always wondered if there was advantage (not including less weight) to going with aluminum block ??

I would expect the iron head/alum block to work better, (theoretically) for a couple of reasons:

1) iron head is stiffer and would bridge across the head bolts better.

2) the head runs hotter than the block. Iron has a lower coefficient of thermal expansion. So....that mix would tend to equalize the thermal expansion of the two and minimize the movement along the deck surface.

But if someone has actually tried it and it didn't work well, that would override theroy.

FWIW,
Eric