I attempted to put an aluminum intake manifold B4B on a 72 block with 72 heads. The heads have an egr passageway in the middle. There are holes on both ends of each head that are not bolt holes. When I started the engine very loud exhaust sounds came out of the holes. So my question is what size freeze plugs should I buy to plug the egr passageways and once that is done can I use the B4B or stock intake only? Thanks.
I believe those are A.I.R. passages in the heads, not EGR. Yes, you can block them. I would tap them and use screw in plugs. https://www.v8buick.com/index.php?t...hup-455-to-alumin-intake.318272/#post-2653638