The Stovebolt Site Forums The Shop Area General Truck Talk tell me about those "split manifolds"

I keep hearing about those "split manifolds" on the ole Chevys.......... supposed to sound really nice, was this the original reason or trying to add some performance? I recently saw a pic of one of the old engines, but the manifold was mostly obscured. I'm trying to imagine what is done. Seems you'd block the manifold and add a second outlet. BUT, isn't there only 3 ports - each common to 2 cylinders? Do you run 4 cylinders out one outlet and only 2 cylinders out the other oytlet? Anyone got a picture?

it is the intake that has 3 ports (2 cyl per port) the exhaust has 4 ports (2 have 1 cyl and 2 have 2 cyl) i would like to hear a I-6 with true dual exhaust have a '84 250 that has factory dual exhaust manifold and 2 barrel carb but i'm thinkin i'm gona throw the head away cause its one of them where the head, intake and exhaust manifolds are all one piece "icky" and it runs for crap won't idle just keeps rackin up the rpm
Nate

Old Iron Chevy,

If you want to hear one, There's a link on KMongo's site where he has a sound clip of his exhaust. I believe he's running a 235 with a split manifold.

SCS 65, I think if you do a search in the forums on split manifolds, you can probably get some pretty good pictures of what they look like.

I know Shipwright has a nice picture of his set that Kansas Customs made up for him.

I had mine split by the radiator/exhaust shop here in town. They placed a block in the center of the manifold, and dropped another outlet out the side.

If you don't find any other pictures, e-mail me, and I'll send you some pictures of my set-up.

The reason an I-6 sounds different with a split manifold is that each successive exhaust impulse comes out a different pipe. With a firing order of 1-5-3-6-2-4, the front flange gets the exhaust from 1,3,then 2, and the rear outlet gets the gas from 5,6, and 4, in order. This creates a unique resonance which can only be (kinda) duplicated from a V-8 with a 180-degree firing order, requiring a special camshaft, crankshaft, and distributor setup. Those 180 V-8's were used mainly in sprint cars, etc., and the exhaust note is definitely different, kind of like a 4-cylinder on steroids! The 120-degree separation of a split-manifold 6 has a resonant frequency unlike any other engine. A set of "steelpack" mufflers, with steel wool instead of fiberglass packing added the final tuning to a split manifold setup, and it would rattle windows for half a block!
Jerry

JUST remember that when you use Tom Langdon's headers as shown in his catalog...
the front header will foul the steering box when fitted to a stock AD truck.
SO
tell Tom the application ie - what engine in what truck. Tom will then cut about 3'' off & re-weld the exh. flange back on the front header to fit that AD application before he ships it to you.
If you are changing steering boxes - that's a different matter.