I look at several car magazines and I'm always seeing things like "57-87 chevy" and then there's a whole different listing for "87 and up w/Cast heads". Could someone please explain the significance between this? I can pretty much figure out on my that the bolt pattern is different, but why is this important when shopping for intake manifolds, valve covers, heads, etc. I believe the LO3 has centerbolt cast iron heads. Is it true vortec is the best heads for a 305? Just wondering. I also think this should be put in the FAQs. Some people are just too embarrassed to ask a simple question like this. Thanks.

 

well the bolt pattern where the intake mounts to the heads is different, so that would make it really hard to bolt on the intake.. I heard you can use a dremel or whatever to lenghten the bolt hole in the older manifolds to fit the newer heads.