what would be the difference if someone was to put cast iron heads on the z or firebird? power loss?

 

No power lose the best aluminums only flow as well as the irons and most flow less than the irons. The irons do have a larger combustion chamber so you would lose a little compression but would gain thermal efficiency probably a draw there call it even, then you would be adding 35lbs. or so to the car. Aluminum holds no magical power advantage over iron and the increase compression it uses is to make up for the extra heat lost to the cooling system(not used to push piston). Aside from weight iron is actually a better material. I am not saying go out and swap in iron heads the aluminums have as noted a weight advantage and screwin rocker studs as well as a little more meat for porting in some cases. Both heads are good but neither is worth swapping for the other unless it is a repair or ported.

 

yes i might have a cracked head and was just woundering about the heads. i could get brand new iron lt1 heads for 250 dollars, cheapest i can find new alum is around the 450 dollar range.

 

I got a set of iron heads off a 96 Caprice (350 block). Cleaned with rockers, studs and valves for $150 + shippin.