My iron 370 shortblock is fully assembled, my cam is being ground, and I have 2 sets of heads, 317 aluminum, and a set of earlier 6.0 iron heads, which I believe are pretty much exactly the same port geometry.

My intent with this engine is a LOT of boost, in a 1995 Impala SS...weight is really not the biggest concern to me, the car originally had an iron head LT1 in it.

With the stock 317 head chamber size, I will be right where I want to be for compression ratio, but I want to re-surface the heads (very very minor material removal) to properly prep them for MLS head gaskets, and then clean the sharp edges out of the chambers to help avoid detonation, and to bring the chamber volume back up where it would have been before decking the heads.

I'm a little nervous about the deck strength of the aluminum heads, especially after decking them, even if I do only need to remove 0.002-0.003" of material from the deck, so I was curious if anyone has much experience with iron heads...again, I'm not concerned at all with the weight difference, or the ease of machining either material head. I'm also not concerned about heat flow in the heads, really only concerned with the strength of the castings.

If you've done much with iron 6.0 heads I'd be curious to hear your feedback...I'm not sure I'll hear much if anything at all, but if you've had any experience with them, good or bad, please let me know.

 

Just run the 317 aluminum heads. There are plenty of guys running the 317 heads and putting over 18 lbs of boost thru them. Just look at this thread, 24 psi on stock heads.

https://ls1tech.com/forums/forced-in...-920-rwhp.html

 

I used the 6.0 heads on my ta that has 18lbs of boost and i love them i started with ported ls1 heads but i found the 6.0 heads will flow more so i used them and i did pick up some power but i had a 383 stroker now im building a 408 with 25+ lbs of boost

 

I'd definitely use the 317s. They are great for stock heads and boost.

 

A lot of people here will tell you to run the 317s just because not many people have experience with the iron heads as you suspect. I run 317s and you can definitely make up to like 1000hp on them with the right setup. The iron heads might provide some added rigidity but you will also get some of the negative effects from them too. You might experience some more detonation with them than an aluminum head as they are more prone to hot spots. This could limit your timing advance as well. It's definitely worth doing some more research, but if you do go with the 317s just use good mls gasket, arp studs, and keep the backpressure in check and you can make good power on them.

 

I read that iron heads have a thinner deck compared to the aluminum. Is this true? I bet there wouldn't be any advantage at all over the 317's then.

 

Yes they do.