Ok, I lready know that switching to a 350 is a better deal than running a 305. But I do not want to change out the entire engine in my '83 with the plain 305 with perimeter valve cover bolt heads.
So my question is, are the newer center bolt valve cover TBI, or TPI (?) 305 heads (I'm assuming they are center bolt valve cover heads) from an IROC any better performers than the older, plain 305 heads? Are they all 58cc combustion chambers? Is it worthwhile trying to find a set of FI 305 heads for a mild engine hop up? If so, are there any special casting numbers to look for? Do you have to also go to a Vortec style intake manifold? I just want to warm the engine up a little, it's NOT going to attempt to be a race car, I just want to increase the fun factor a little over the stock smog dog, but I don't mind changing over to a Vortec manifold and center bolt valve covers if I need to. Thanks.

 

Swirl-port TBI heads of any vintage are to be avoided. Your existing heads (LG4?) would be fine. There's no performance difference between center-bolt and perimeter bolt heads.

 

True that. I have a 350 with my LG4 center bolt heads from the original 305. They work just as well as the 350 heads. The center bolt valve covers came into affect in 87 for all chevy V8 engines. So if you keep the heads you have on there, you will probably be fine.

 

Better, usually... you don't give up compression.