i am sorry if this might not be an advanced tech question but it does have to deal with a Gen VI and V 454 big block

i am seeking for a Gen VI 454 and i was wondering can heads off a Mk IV BB fit on a Gn VI,V i dont think they will fit because of how they have a different coolent opennings in the heads im i right on this?
and would aftermarket heads works?

 

You can use the Mark IV heads on a Gen VI block. You cannot use Mark IV heads on Gen V blocks. Just make sure you get the right head gaskets. I have a set of Gen VI heads just sitting.
Important tech note:
Use of the adj. MK IV head is not recommended for use with the Gen V block. Changes in the config. of the Gen V's coolant passages allows coolant to seep into the lifter valley. All Gen VI blocks will accept MK IV heads because the coolant water holes were decreased in size. The Gen VI cases have all aluminum timing covers with six bolt holes, not the sheet metal cover.
I think your question is fine for the advanced section. I would like to throw this out for discussion. Common thought is that oval port heads are good to 6000 rpm, best for low end torque. Square ports are best above 6500 rpm. If so why did GM use Square ports on their crate motors that redline at 5800 rpm?

What are you trying to do with your combo?

Guido
Only eight more posts to go....

 

I believe John Moss at GM used gen 4 heads on a gen 6 block in the concept "Coolside II" truck. Look it up on google. If my memory serves me correct they achieved 575 or 675 hp w/ this setup.

 

oh yeah i am not going fully drag with this car but i am just looking for the cheapest way to get in the mid to low 12's without using nos or blowers
i think chevy hi performance magazine did an artical about the question you have but i really dont remember much about it

here's a question is aluminum piston's better then iron?
many tests have been done with this and aluminum proves to be better for performance, but alot of people think that with the right combo iron would prove to be better