Exhaust manifold diameters & casting #'s

[Tony 38901]

Amybody know where I could find an online source that lists the diameters & casting #'s of all the exhaust manifolds used on 63-72 'vettes?

[Mike M.]

Re: Exhaust manifold diameters & casting #'s

NCRS spec guiode will give you all the casting #s. for the most part, a solid lifter sam;ll block will have a 2 1/2" exh. manifold while the hyd lifter varities will have 2" exh manifolds. there are exceptions. mike

[Duke W.]

Re: Exhaust manifold diameters & casting #'s

There are only three 2.5" manifold casting numbers and they were only used from
'62 to '65 on 300 HP with manual trans and all higher horsepower engines.

3797901
3797902
3797942

The 942 is the rarest. Functional aftermarket equivalents are available, but recognizeable as non-GM.

Duke

[Joe L.]

Re: Exhaust manifold diameters & casting #'s

Duke-----

There's one other 2-1/2" outlet manifold. This is GM casting #3846563. It was used for 1964-65 applications with left side alternator mounting. It has the alternator bracket on the forward end of the manifold rather than the side like the '901' and '902'.

[Duke W.]

Yup, thanks. I missed that one *NM*

[Jim T.]

Re: Exhaust manifold diameters & casting #'s

Duke is the 942 for the FI engines only without the choke heating connection?