What all is involved in using GM 502 heads work on a MarkIV block. I know the coolant passages are different, but curious if it can be done and if it is feasible?

Thanks guys graemlins/beers.gif

there used to be a conversion head gasket available through Apple chevrolet, i think. check with scoggin dickey, they might have them.

I used Gen 6 heads on a MK IV block. Nothing to it. Use a MK IV head gasket for standard MK IV coolant circulation, or use a Gen 5/6 gasket and drill a couple of holes in the block deck on each side for Gen 5/6 coolant circulation.

As far as I know, the Gen 5 heads have the same coolant openings as the Gen 6 L-29 heads I used.

The problem child is using the OLD heads on the NEW block.

Schurkey, The new Gen 6 L-29 head is the new Big Block Vortech Head, right? How good did it run? I was just wondering if this head has much power potential.

Originally posted by Schurkey:
I used Gen 6 heads on a MK IV block. Nothing to it. Use a MK IV head gasket for standard MK IV coolant circulation, or use a Gen 5/6 gasket and drill a couple of holes in the block deck on each side for Gen 5/6 coolant circulation.

As far as I know, the Gen 5 heads have the same coolant openings as the Gen 6 L-29 heads I used.

The problem child is using the OLD heads on the NEW block. Is the Gen V heads different from the Gen VI heads or will this only work with Gen VI heads? To me the GEN IV has one coolant hole in the block whereas the Gen V has two in the head. If you use the Gen IV gasket in the gen IV block it will seal off the passage in the head no? :confused:

I've never seen Gen 5 heads, so I can't comment about the coolant passages, except to say they use the same head gasket as the Gen 6, and therefore I believe anything that applies to the Gen 6 heads also applies to the Gen 5 heads.

Both the MK IV and the Gen 5/6 have coolant openings at each end of the head. This is so one head casting can be used on either bank. The Mk IV block does not have a coolant hole at the front of the block, but the Gen 5/6 does. This is why OLDER head on a NEWER block is such a bitch, but NEWER heads on the OLDER block is no particular problem.

The L-29 heads on my 454 produce more power than the peanut port junk that they replaced. What I can't tell with any accuracy is whether it's because the old heads needed valve work, and had larger chambers for lower compression, or whether the L-29 Vortec heads are better than an old-design big oval port closed chamber head. Changing the heads also included adding a Performer RPM manifold and 850 vacuum carb, versus the Torker 2-O and 650 DP of the old combo.

I am somewhat disappointed, I expected a larger power gain, but with the crappy summer, I did zero tuning. (This engine is in my boat.)