C-1&2 Exhaust Manifolds 1 1/2 question

[Isaac Tyson]

Need some help identifying these exhausts. I picked them up thinking I knew what they were, but found out I wasn't so sure. They are 901 and 902 exhaust and I thought that they would fit high horse power 62 63 64 65 Corvettes. But, someone told me that LH side is a 1962 fuel inject specific exhaust because the bracket on the end is shorter that normal. They also pointed out that on the RH exhaust the "spacer" that normally has the heat valve was not drilled and that there was no valve--making it a "spacer" for a fuel inject car only. (sorry for the lack of terms). Anyhow, the RH exhaust does have a drilled hole for the heat tube, so I know it's not a fuel inject manifold. However, if all that is true, isn't this sort of a strange set up seeing as I bought it from someone who was possitive it came off his personal car and that it was a matching set?? (not sure what engine he had).
Hey any help here would be great!!!!!
THANKS

[Isaac Tyson]

2 1/2 not 1 1/2 sorry for the mistake. N/M *NM*

[Joe C.]

Re: C-1&2 Exhaust Manifolds 1 1/2 question

Isaac,

The bottom manifold pictured, looks like a 3797902. This has a 2 1/2" outlet, and is used for right side 300(with M20), 340, 350, 360, 365, 375 HP engines 1962-1965. It is pictured with the spacer installed, which is a blank heat riser spacer used with fuel injection. The 902 has the choke heat tube installed, which is simply not used for fuel injected engines.

[Joe L.]

Re: C-1&2 Exhaust Manifolds 1 1/2 question

Isaac-----

These manifolds were used on 1962-65 Corvettes with 300 hp (standard trans) as well as 340, 350, and 365 applications. They were also used on some 1963-64 passenger cars with 300 hp.

Most, if not all, 1962-65 Corvettes with FI used a left side manifold with no generator bracket, at all.

[Joe C.]

Re: 2 1/2 not 1 1/2 sorry for the mistake. N/M

Isaac,

The upper manifold is a 2 1/2" right side manifold. This is the preferred manifold used to "create" a 3797942: the fuel injected left side manifold with a plain front (no bosses). Some creative grinding, surfacing, epoxy, and a trip to be ceramic coated will create a nice, home made 942.

Joe

[Joe C.]

G@$H DAM^ EDIT

The upper one is a left, not right side. 1964-5 Corvettes used a 3846563 left hand side manifold, which have a different forward boss with two forward facing holes for the alternator brace (for engines with compressors). I am not certain which years used the 901 left side casting.

[Isaac Tyson]

THANKS...one last question...

Thanks guys for the help. So now that I understand a bit more what I have, I'm still mixed up about the "blank heat riser spacer." How comes it's on these manifolds if it's a fuel inject item?? Should I take it off or leave it on??
Thank You!
-Isaac

[Dick W.]

Re: THANKS...one last question...

FI engines used this spacer when the heat riser was removed. It makes the exhaust system align as it should.

[Tracy C.]

Re: THANKS...one last question...

Issac,

If the right hand "902" doesn't have a choke tube inside, then this is off an F/I car. And consquently, the manifold is a VERY valuable piece.

If it does have the choke tube, then it is off a carburated car. You can use the spacer as is for either F/I or a carb car because it isn't uncommon to wire the heat riser butterfly open anyway.

tc

[Mike E.]

Re: THANKS...one last question...

The answers you've gotten need to be supplemented a bit:
The 901 (left hand)is correct for 1962 300, 340, and 360HP motors. It needs to have the mounting boss because in 1961 and 1962 the expansion tank was mounted on a bracket that mounted on the left hand manifold.
The right-hand manifold (902) is also a correct application for 1962 300, 340, and 360 HP motors. If it has no hole top or bottom for the choke heat tube, then it is correct for the 360 HP (FI motor). If it has a choke heat tube hole top and bottom, then it is correct for the 300 and 340 HP motors. The spacer (which was used for FI) was often bought over the counter and substituted for the heat riser assembly, so it does not imply that the manifold was used for FI. The mianifolds that you have appear to be original equipment manifolds. For a number of years GM sold a service part that had larger casting numbers and the casting slag ground off the top of the manifolds. Current reproductions are very good, but they have a different number of casting "bumps" along the top than do the originals.