I want to fabricate an intake manifold for my 261 as a welding/tuning project. My idea is to fabricate it out of sheet metal and tubing, with a bottom compartment for water heat. I want to do it in the style of the GMC 5 carb Nicson manifold but I have a set of Holley 94's I want to use. I want to try a 2 carb and then 3 carb setup.
The question is what gauge of tubing is best and should I use Aluminum or Steel and what alloy. I have a Lincoln Migpack 135, which can handle 1/8" aluminum with preheating and argon or 16 ga. without preheat. Steel, however, is easier to weld, I can handle up to 1/4", but I am concerned about internal rusting. I have a spare head to bolt the whole mess up to while I am fabricating. I think aluminum would be better, in looks anyway. Any suggestions?
Stainless is out since I lack the equipment to weld it and I just want to do this as a fun winter project. I don't want to do any castings or much milling, so things like billet are out. I plan to post my results and plans on the web when I am done.
I am doing this mainly because I don't like tuning 1bbl carbs, I have a collection of small 2bbls, there are no manifolds available for that carb with the big 261 ports, and I don't want a 4bbl either. I also want to be able to say that I did it!
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1950 Chevy pickup with '62 261, 4 speed.
I like your idea. I'm going to try to do something similar myself. I don't know much about welding though. On the other hand I have a college machine shop at my disposal so I've got a bit flexibility there. I've told myself though that the intake would be the second project. I want to rig up a fuel injection system for my 250 first. But either way I'm all talk right now. So we'll see. I can't offer much help but good luck!
4onthefloor, There are manifolds that use the Ford/Holley 94s or other 3 bolt base carbs. Edmunds custom made them and Tom Langdon had two of them at Hershey last week. I have one on my 261 and they work fine. Unless you are going to run some high rpm's two of those carbs are about all you need for a street driven 261. I also have interest in fabing a manifold for three side draft corvette carbs. Maybe we can compare ideas.
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Gael
37 chevy sedan, 261,t5
57 pickup
58 burb
Well, I'm really impressed with the talent that's out there. Way Cool! You better jump on that one Gael!
RapRap
1940 Chevy Coupe
Chevyman, I had one of those, and it had small ports like the 216. Unfortunately, the flanges on it were too small to seal well with the head (848/850 size ports) so I sold it to a guy with a 216. I don't care to purchase another in hopes that it will be better.
Thanks for the link, Curtis, that's the kind of thing I'm talking about. I'm not set up to weld stainless though.
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1950 Chevy pickup with '62 261, 4 speed.
4onthefloor, I really like the idea of building your own intake. I work in a foundry and have toyed with the idea of pouring a intake for my 250 out of aluminum but never got around to it.
I would build it from aluminum. The only thing I would be concerned about is the design of the runners and getting a good seal on the head.
Gregg
4onthefloor - have you talked to your welding equipment dealer about your machine's capabilities on stainless? I'm not familiar with the Migpack 135, but I'm assuming that it's a 115V, 20% to 30% duty cycle system. That might be too small. If your dealer thinks that it can handle the output, you can purchase cored or solid MIG wire and a small argon/oxygen bottle that works fine for connecting stainless to stainless or to mild steel. Go to this for a brief discussion:
http://www.lincolnelectric.com/knowledge/articles/content/migweldss.asp ------------------
David
newbie #4153
I have a Miller 135 MIG welder, 30 percent duty cycle,120 volt, solid core wire with a tank. It can handle welding 14 guage stainless with either the steel wire(rusts) or stainless wire with athe proper gas mixture. But regular steel tubing is cheaper and so is a can of paint to dress it up.The thin stainless or common steel tubing may be hard to keep warm even with water heat, may have to insulate the tubing to contain the heat.Aquire a junk head to fab the manifold on to keep everthing in alignment.
TowTruck, what exactly do you do to work at a foundry? What does that mean? I'm taking advanced manufacturing at college and one of the things we're studying is casting processes. I'm just interested in what you think of it and what it involves cause I'm not sure exactly where I'm going after school.
Does anyone know how difficult casting is? I saw a piece somewhere on the net, from a link on here if I remember, on some one who was casting a bunch of manifolds for a slant 6. It didn't look too complicated. I think he was doing it pretty much in his garage. Right now I'm still leaning towards machined flanges and welded pipe sections but the idea is interesting.
As for sealing, couldn't you just cast the piece with some extra thickness along the flange and then have it machined? I'm not sure, I've only been working in our machine shop for a month now so it's not my specialty. And for the welding I think getting a junk head would be best. Just mount everything to keep it aligned. Again, if you increased the flange you were working with you could have it trued afterwards I believe. Just if you were still worried about the sealing. It would be a way to be sure.
I think I would rather use aluminum than stainless, it conducts heat a lot better. My welder is recommended for aluminum use with the $55 kit they sell. I want the intake to still be separate from the headers, I would rather not have to re-do it when the headers burn out. I would like a set of fentons, I think.
I guess I'll get some stainless and aluminum tubing and practice and see how good a weld I can do before I make a decision. I do have a spare head, a spare engine even, on a stand in my garage to fit everything to.
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1950 Chevy pickup with '62 261, 4 speed.
You should use good thick flanges where the manifold bolts to the head. I don't think your 110v sheet metal welder will have enough heat to penetrate a thick aluminum or stainless flange. Be sure to test your practice welds real good. If the manifold cracks from vibration while driving, you could cause some serious damage to your 6.
Jim R
Yes, I agree with Jim. I just finished a 3 x 2 sheet aluminum intake and had to use 180 amps on my TIG welder to stick the carb pads to the plenum box.
Thanks, those are the kind of tips I was looking for.
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1950 Chevy pickup with '62 261, 4 speed.
How bout the top of this chair...and box it in the middle to hold the carb with a middle tube...2 1/2" tubing...
I think I'm going to take a crack at it.
www.fungusworks.com/TheShow/html/Exhaust.html CT
Got any pictures, Frenchtown?
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1950 Chevy pickup with '62 261, 4 speed.
I have also maded my own intake system out of sheet metal. which is a 3x4 tunnel ram
You can see it @
http://www.memorylaners.com }[oooooo]
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NovaMan/Twisted6/Larry