C-2; 1964 Exhaust Manifold PN 3747038 FUEL INJECT?

[Isaac Tyson]

When I was doing some engine work on my '64 (327 ci 250 hp w/ powerglide trans) I saw that my right side exhaust had a big old crack all the way around it! So I took it off and bought a new used one--numbers 3747038. However, when I got it, to my dissapointment there's no choke tube or choke tube holes in it!!!!!! So the question is, WHY aren't there any choke tube holes??? I used my little white NCRS book to look up the numbers, and it says that the 3747038 is correct for the car and for that side. FI manifolds were a different number and 2.5 inch. So what do I do with my new boat anchor and why aren't there any stinking choke tube holes!

Thanks!

[Tom H.]

Re: C-2; 1964 Exhaust Manifold PN 3747038 FUEL INJ

I believe the 3747038 manifold was used on other applications other than Corvette. My guide lists it to be used on 283's and 327's from 62 to 68. Both on Corvette and full size Chevrolet. My guess is the manifold you got was not originally installed on a Corvette.

[John D.]

Re: C-2; 1964 Exhaust Manifold PN 3747038 FUEL INJ

Isaac, To echo Tom's answer the carb exhaust manifold on the passenger side had a choke tube hole going thru it. If you wanted to you could buy a nice repro heat tube made out of SS and have it easily installed in your exhaust manifold. Wouldn't take a rocket guy to do that job. Would be nice though to get it at the right angle, etc. But since you have your old one it would be a piece of cake. Might want to take the new one to a machine shop and have them drill it for you and press in the new heat tube. It's been done before for sure. Most of the time those heat tubes are solid rust anyhow.
The same scenerio applies to the 2-1/2" pass side ex.man. Carb one had the tube and FI didn't. Same identical ex.manifold. Same casting number. Many FI cars out there with welded up choke tube holes for sure. All original FI cars though. JD

[Isaac Tyson]

THANKS....

THANKS for the info. I'll throw this one away and try to find a real Corvette Manifold. I guess I'm learning not to take people at their word all the time. So it goes, no big deal.
Thanks again

[Tom H.]

Re: THANKS....

Always remember when buying vintage parts............. even if their word is good, their knowledge may not be.

The key is to be educated on the parts you are buying. Heck I've been learning my whole life and I'm still learning every day, thanks to the guys around here.

At least you learned something from the experience and you'll know exactly what to look for now. I've bought many parts twice already !!

[Joe L.]

Re: C-2; 1964 Exhaust Manifold PN 3747038 FUEL INJ

Isaac-----

As others have mentioned the GM casting #3747038 manifold was used for many other applications some of which did not require the choke hot air tube. The only Corvette applications for the manifold was 1964 and some 1965 with Powerglide and/or C-60. The Corvette applications require the heat tube.

Curiously, the version of the manifold without heat tube is quite rare. It was used only for certain 1964 passenger cars. Of course, I don't know how many folks are restoring those cars, but those that are would probably cherish the manifold you have, just like some Corvette FI folks cherish the no-heat-tube version of other manifold castings.

As others have said, you could have the manifold easily converted by a machine shop to heat tube configuration. It would be a snap for a competent machine shop. However, it seems somewhat a shame to convert what could be a hard-to-find piece, albeit not for a Corvette.