I did a search but could'nt get the answer I need, so here goes... Can I run the larger port 365 and 390 exhaust manifolds on my early small port 1950 331 engine ? I read that the bolt pattern is the same and the later ports are bigger but will the bigger port manifold work on a small port head ?
There's quite a difference in port size between the two. There were three basic port sizes, according to old header listings: '49-'51, '52-'55, and '56 and up.
I would imagine so. all the aftermarket stuff and header kits are listed 331-390 with no differentiation. might not be any benefit as far as flow goes, but i imagine it should work.
They will work. I have a pair of 1950 331 manifolds and they are cool looking, but very small. I'd say the later manifolds would do some good.
If, as it seems, the bolt pattern is the same, the next thing to determine is if the machined flat surface area around the smaller port is large enough to mate with the large port manifold and still have enough contact area to seal adequately. If you have access to the later manifold it should be fairly easy to determine the contact area. Ray
no but put 390 guts in a 365. I think it works through all of them. pistons are 390 specific CANNOT run 390 crank and 365 pistons.
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