I just got a set of aluminum ZZ4 heads I currently have a 91 RS that I swapped in an 87 IROC engine. The block was originally a 305 but I switched out the block to a 350. The heads are still from the 305 but this is where I run into problems. I did a search and I sort of understand but not totally. I was wondering, since the ZZ4's didn't come with rocker arms, if I could still use those for the new heads. Also, would it be worth even doing that or would they just killed the ZZ4's potential. If I can't use those rocker arms, which should I go with. Should I get the regular rocker arms or go with the roller rocker arms. I'm leaning towards 1.5's but should I go with 1.6's instead. I'm really not sure about this and any help would be appreciated. I am not to sure what kind of cam I've got but I know it is not stock.
Thanks

 

Let me get this staight. You have 305 heads on a 350. Dude you have major compression and no flow. Put the ZZ4 heads on. As for rockers you may want to check with a gm performance parts dealer. I think you may need self aligning rockers. As for your cam that does make a differance when coupled with higher spring pressures. Without knowing cam lift I don't know how you are going to properly match springs, or have adaquete rockers. You will need to know what cam you have.