Hey guys, new user here just getting started.
I have just rebuilt a 235 and am in the process of adding duals. I haven't seen any split manifold jobs other than on the Kansas Kustom page and was looking under the hood and thought there might be a better place to put the flange than on #4, what about #5?
I have sent a stock manifold to be split. I was wondering if anyone here had any pointers as to where, on the rear manifold to place the flange?
Dear Giddy;
Those rarely work as your welding steel to cast iron. I saw dozens of those in the 'fifties' because headers had not come of age yet.
Your best bet is the Fentons, from Patrick's.
I would put it back stock till broke in & all that. Save the $ & get a Mc Gurk 2 pot & Fentons as a add on package later.
Good luck, John M., #3370.
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My two bits is that the old method can still work. I've hade a homemade split manifold on my 230 for 30 (yes, thirty) years with no problems. With nickel rod and some patience this can be done. I picked a spot on the side of the ex. manifold behind the center outlet. Drilled as many 1/4" holes in a circle as it took to remove a round section of the manifold wall. Cleaned up the edges with a grinder, and welded on a water pipe elbow - 2" I think. Cut the bottom flange off a scrap manifold, and welded that to the bottom of the elbow.
Then ahead of your new outlet saw thru 3 sides of the manifold in 2 places just far enough apart to insert a section of 3/16" mild steel plate as a block off. Then weld around the 3 sides. There will be some leakage between the front section and the back, past the 4th side of the blockoff, since it is just touching the back wall. But this will act to cut down a bit on the harsh rap rap produced by a complete split. If you can, have the manifold bolted to a spare head when you do the welding, to minimize warping. After you are done, take it to a machine shop to have the block mating surface planed.
I did almost the same thingto split a stock manifold. One thing youmust remember when welding cast is to either preheat the whole manifold, weld, then bury it in a pile of sand so it cools slowly or only weld about
3/8" long bead at a time. Wait til the next day and weld another 3/8" and repeat that til it is all done. If you introduce a bunch of welding heat in one spot you will probably crack the manifold. Good luck
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Gael
37 chevy sedan, 261,t5
57 pickup
58 burb
My expert manifold splitter, welds in a block off plate down inside the hole towards the back, to block off the back three cylinders. (that's looking straight down inside the 235 exhaust, once you pulled off the intake).
Step two, he blows a hole somewhere along the side on the back half between the center and the firewall, depending on where you want aft pipe to locate.
Finally he welds on a cast iron elbow over this hole. This elbow has a flange to bolt exhaust pipe to. This iron flange is getting to be difficult to find now days.
Also, he welds closed the heat riser baffle so as not to constantly blast the bottom side of the intake.
I guess now all you need to do is find a really good welder of cast iron in your area. My guy is in central Calif.
Best of luck.
Thanks guys,
I had read some references to blocking off the manifold yet allowing some of the gasses to pass to the other side so you don't get the hard rap. I don't want a LOUD sound just a mellow tone. Really appreciate the input.
JC
FYI, Kansas Kustoms does the manifold splitting for Night Prowlers.