The Stovebolt Site Forums The Shop Area Engine Shop GM split exhaust manifold - facts or fiction

I have a chance to purchase what I am told is a GM split exhaust manifold. I have not seen the exhaust in person but am told his is an original GM part. I know the casting number for the original split exhausts was 3836108. My question is this, was there a GM replacement/aftermarket split exhaust manifold? I want to make sure I am buying the real deal before I lay down the cash. IF it is some sort of GM replacement part, that's okay, but I want to know that before I try to negotiate or purchase. I know the 3836108 split exhaust manifold came on 53-54 Corvettes and the thread below goes into that in great detail. There is no mention though of an aftermarket or replacement GM split exhaust manifold part number, if one even exists. Thanks!

3836108 Stovebolt discussion

Here is a link to a Hot Rod Magazine article by Racer Brown, circa 1955, that shows the vette factory split manifold, if that helps:

http://www.selectric.org/55chevy/soup.html

According to the guys over at the H.A.M.B. there were more over the counter GM split manifolds sold than the ones that came on 'vettes. Check that out here: http://www.jalopyjournal.com/forum/showthread.php?p=6367137

Your casting number is the corvette split manifold. I think it was the only version released by GM. They were sold as a factory performance item and as mentioned, probably more crossed the counter that way than were released on production corvettes. They are bringing pretty good money right now so be prepared.

I had the opportunity to get one of those cheap, along with the complete tri-carb manifold. My Dads cousin was a member of the Midwest Corvette Club, and had a line on a stash of oem Corvette 235 parts. Wish I had taken him up on it.

I would like to find one for my 37 but they are a little too pricey for my budget.

As an alternative find a welder friend and make one. IMO done right means 2 identical studded, flanged, beveled outlets just like the vette one.

I actually found a split manafold like the corvette one at a swap meet some one had made and has a polished silver powder coat on it and paid about $120 for it. Works and sounds great!

I found one at Pate swap meet Thursday for $500. I offered him $300. He still had it when I left.

We did a flow test on the GM '54 Corvette Split exhaust manifold. the flows were about 22% greater than a stock single outlet exhaust system. The comparison with the headers showed they were allowing the movement of about 28% less flow than the headers would allow. Flows do mean something and I interpret that as being useful to make horse power. The best flows we did obtain came from the Fenton and Shop manufactured tubes.
Normbc9

Could you elaborate on how these tests were performed? When I hook a ½” garden hose to the tap on the front of my house and a 2” fire hose on the one in the back they both flow the same. Why? Because the flowrate is determined by the size of the valve and it’s surrounding geometry. IMO the GM dual manifold (or reasonable facsimile) is more than adequate to keep up with this head’s ability (or lack of it) to expel exhaust but am open to being proven wrong.