I just aquired a fresh rebuilt 1975 455. I want to run this motor for a while in one of my 70 GS cars so I want to use a stock 70 Intake manifold for appearances,however, the heat crossover hole is very large in the head where it will mate up to the 70 intake.The casting inside the the heat crossover is rough and unmachined so plugs cannot be installed like on a 70 head to plug holes.Has anyone got a solution for this or will I have to use a 72 and newer intake to cover this crossover area. Any help would be appreciated Thanks
Has anyone ever put a 70 intake on 72 later heads and block? If so ,how did you block heat crossover port in heads? I appreciate anyone's response Thanks
i kinda asked thid q a while back,hard to get an answer on this one everybody just told me the 75,76 heads are smog junk,low compression boat anchors.will an aftermarket intake cure the problem?my 75 engine had a performer on it that worked,but i bought it less intake and carb.so im in the same boat as you.ive been monitoring your post to see what kind of answer you might get............good luck
Try the bench. Just post it there where there is more traffic. You could always find an older set of heads. I run a set of ported 70 heads on a 73 block. Use the head gaskets for the year block. Heads are an easy start and will help a little with the low compression pistons. Top it off with a good intake and you will see a difference.
I kinda had the same problem. Performer intake on a 76 block. Different cross over sizes. I slapped it on made sure I had a good seal and had no problems.
Thanks for your responses. I may have to run a 73 intake on this motor to cover the heat crossover Thanks
I'm not sure what you're willing to do, so I'll just tell you what a friend did and let you decide if it was a good idea. He had a 74 455 from a junk Riviera he came across. He pitched the intake and wanted to use one from a 68 430. He plugged the holes in the exhaust runner with aluminum and filled the other end with epoxy. He filed it smooth and it got painted. He welded the air injection holes shut. You'd have to look at it to see what he did. At a glance you wouldn't even notice. He put a few thousand miles on it with no problems, so it doesn't really seem like a bad idea to me.
