'67 327-350 exhaust manifold help

[Kent S.]

The previous owner installed headers. I want to return to original style exhaust manifolds. Car has side exhaust. I would like to find 2 1/2" manifolds to install.
In order to limit junkyard time,can anyone tell me: 1)what models and years of GM possibly had 2 1/2" and is there an easy way to distinguish between 2" and 2 1/2" with a quick peek under the hood ? 2)are there particular casting number prefixs that identify 2 1/2",(such as 384----),or will I have to find specific numbers and what are those numbers. 3)If the exhaust manifolds are not originally from a vette, will that affect the installation of the ignition shielding and side exhausts? 4)Is there anything else I need to know before heading to the junkyard?
I'm a new member and I'm sure these questions have been answered before, but a guy could get lost in that fantastic archives. Thanks for your help . Kent

[Mike McKown]

Re: '67 327-350 exhaust manifold help

Kent:

If you want to limit your junkyard time, call ahead. I doubt you will find any 2 1/2 inch rams horns on junked cars. It has been years since I have seen one on a salvaged vehicle. They were usually snapped up as soon as they hit the lot. If you persist though, you might take a guage or calipers with you to measure the pipe size. The radio shields mount to brackets so they will interchange with pass. I think your '67 altrnator mounts on the left. Make sure your manifold matches whichever side you want to mount it on. The numbers, I'll leave to somebody else.

[Joe L.]

Re: '67 327-350 exhaust manifold help

Kent------

The 2-1/2" outlet Corvette exhaust manifolds were never originally used on any other car besides Corvette. So, you're unlikely to find any in a wrecking yard unless you get real lucky and find a non-Corvette that someone had previously retrofitted the manifolds to. If you have that idea, you're going to be spending a LOT of time in salvage yards.

The 2-1/2" outlet manifolds were NEVER originally used on a 1967 Corvette. The last year that they were originally used on Corvettes was 1965. However, you can retrofit them to a 1967 Corvette if you're not concerned about correctness.

The manifolds you need are still available from GM. These manifolds do have some minor casting differences from the originals but since they're not correct for your car, anyway, this should be of absolutely no concern.

The manifolds are as follows:

left side----GM PART #3846563 (cast GM #3846563)---GM list $151.24

right side---GM PART #3814970 (cast GM #3797902)----GM list $151.24

The right side manifold described above will have an unused, 62-65 style generator mounting bracket at the front of the engine as installed on the car. If you would prefer to have the unused bracket at the rear, then use the following manifold:

GM PART #3797901 (cast GM #3797901)---GM list $151.24

If you wish to have a right side manifold with NO unused generator bracket, then you will have to obtain a reproduction of the GM #3797942 manifold which is no longer available from GM. It's price is about $300 in reproduction.

[Joe L.]

Correction

Kent-----

I was incorrect regarding the fact that the 2-1/2" outlet exhaust manifolds were not used on passenger cars. They were used on 1962-64 passenger cars with 300 hp 327 (L-75). I don't think that you'll find a lot of these cars in salvage yards anymore, though. In any event, at the price of the new manifolds from GM, especially from a competitive dealer, it's hardly worth looking for them for your particular application. Used manifolds might be the best thing for someone looking for exact, original configuration (not dates, though, as the 2-1/2" outlet manifolds were not dated), but, otherwise, NEW manifolds are better than USED manifolds.

[Eugene B.]

Re: Correction

Kent,
For used, correct exhaust manifolds, I suggest that you contact Jet Vette. Jim has a good selection. Cost of correct manifolds will be about the same as new reproductions. His number is 630.513.5949.

Good luck,
Gene

[Joe L.]

Re: Correction

Gene-----

In this case, correct manifolds are really a non-issue. After 1965, the 2-1/2" manifolds were not used on small block Corvettes. So, if they are retrofitted to a 1966 or later Corvette, they will "automatically" be incorrect. Consequently, the issue of exact original configuration is irrelevent. For this application, I think a NEW GM manifold would be the way to go over a USED, "correct" original, especially for the same cost.

[Eugene B.]

Re: Thanks Joe for the clarification. *NM*