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welding on exhaust manifolds

Discussion in 'The Hokey Ass Message Board' started by ab_51Ford, Aug 13, 2013.

  1. ab_51Ford
    Joined: Jan 16, 2006
    Posts: 276


    Dropping a small block Chevy in my Shoebox. I need to either build my own headers or pie cut my rams horn manifolds. Can I weld it up the manifold with a TIG welder, or with I need an acetalin torch?
    Thanks fellas
  2. fiddy
    Joined: Sep 24, 2009
    Posts: 163


    Your tig will spit and pop and have porosity. You need to weld with a high nickle rod or braze the manifolds.
  3. blackcreek
    Joined: Apr 3, 2013
    Posts: 22


    It sounds like if you have to ask you do not have the skill to do it.If your talking about the original cast iron xhaust manifolds you are probabably in over your head. Cast iron is a totally different breed of cat and dirty cast is even worse. Pony up the money and buy a set of headers.
  4. oldolds
    Joined: Oct 18, 2010
    Posts: 3,116


    A bit of a hint about cast iron. Usually if you hit it with a grinder and it throws off big red sparks you can weld it. No sparks or thin little sparks it's going to be problems.

  5. Weldemup
    Joined: Dec 12, 2003
    Posts: 178

    from Central,NY

    Cast iron exhaust manifolds are a bitch.They're hard to prep(carbon and junk on the insides)and even with nickel rod they weld shitty but they can be done.I relocated the outlet on a 383 Chrysler manifold using a torch,cast iron rod and flux. I tacked it then heated it in an old charcoal BBQ,welded it up and covered it up with burning charcoal when done.We had to clean up the slight warp in the flanges with a belt sander,but it's been running in a friends 59 Ford truck for over 20 years with no problems.
  6. williebill
    Joined: Mar 1, 2004
    Posts: 2,694


    Try other SBC manifolds, they aren't all the same, even the rams horns. Not sure, but I think the Nova ones are angled back. My old '39 had a 265 left manifold, to clear everything. A particularly shitty design, but it worked, and cleared everything.
  7. My .02C And Nova manifolds are angled,as SOME impala's.....Hunt around first!
  8. Tcoupe
    Joined: Nov 14, 2003
    Posts: 314


    Ive welded cast iron manifolds with mig a couple of times, many miles and no problems...maybe I just got lucky. I did heat them up in front of a propane heater then stuck them back in the heat after welded so they wouldnt cool too fast.
  9. Slimmey
    Joined: May 7, 2013
    Posts: 87


    I did the same with a mig as tcoupe. I had a customers '63 vette that had broken the bottom flange off in a collision, but we could not find a proper date code replacement at the time so I welded it. It's still holding, that was 22 yrs ago. They claim it does not work, I may also have just been Lucky

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  10. If you want to tig it,
    Pre heat as any cast welding job.
    Clean it as close to perfect as you can get.
    Use silicone bronze filler rod, it will be great.
  11. ab_51Ford
    Joined: Jan 16, 2006
    Posts: 276


    Well you don't acquire skill until you have tried a couple times, fail sometimes and succeed sometimes. Have to ask questions first to know how to do it right? Didn't say I was going to do it right the first time out with no problems. If it doesn't work out, I'll build my own!
  12. Barn Find
    Joined: Feb 2, 2013
    Posts: 2,317

    Barn Find
    from Missouri

    This is good info. I'm tempted to try his on a cracked boat manifold.
  13. no55mad
    Joined: Dec 15, 2006
    Posts: 1,864


    I've welded cast iron exhaust manifolds by using an oxy/acet torch in one hand heating the weld zone, and stick welder in the other hand with nickel/cast iron rod. Prepped the weld with a V groove, then glass beaded the weld area, and wraped in a weld blanket after the weld to control the cooling. Held up fine.
  14. ab_51Ford
    Joined: Jan 16, 2006
    Posts: 276


    Iv tried a couple sets, Impala, Chevy II, late model pick up, nothing really seams to clear the steering box.
    Joined: Jul 20, 2006
    Posts: 2,422


    Years ago when I installed the Mustang II in my 39 Deluxe, I had to modify one of the Pontiac exhaust manifolds for it. I mig welded it, and never had a problem with the manifold. I had to surface it to get rid of the warpage, but other than that, it worked great
  16. fiddy
    Joined: Sep 24, 2009
    Posts: 163


    Another option might be the 80s chevy pickup "log" manifold that sits above the spark plugs. Had to use one of these on a V-8 swap into a 50 chevy with the stock steering
  17. There's no rule that says the pipes have to go down by the bell housing.
    The ram horns are center And Them crazy fords had the pipes running down front.
    You could come down the front just as easy especially since its in a ford any way.
  18. henry's57bbwagon
    Joined: Sep 12, 2008
    Posts: 676


    ab, that is my approach to building cars. Why people are so negative I do not know. If none of us experimented or tried we would not be hotrodders, just guys that buy parts and put them on.

    The welder at work used to use a (Nirod?)stick rod to weld CI

    I set up exhaust manifolds in a milling machine and cut an angle on them so the outlets were closer to the oilpan to fit inside a model A frame.
    Joined: Nov 22, 2005
    Posts: 7,591

    from SIDNEY, NY

    I've had good luck brazing exhaust manifolds. Have you tried bolting a passenger side manifold on the driver side? SBC manifolds interchange side for side, and what with the several different styles they used over the years, there's got to be something that will work for you.
  20. ab_51Ford
    Joined: Jan 16, 2006
    Posts: 276


    Any special wire for the MIG?
  21. ab_51Ford
    Joined: Jan 16, 2006
    Posts: 276


    Yeah iv tried swapping sides. The exhaust is one of the biggest challenges on a SBC in. Shoebox so I knew it would just be bolt in and go. There are quite a few threadswith people asking about different manifolds,but no one seams to have found a good complete swap.
  22. saltflats
    Joined: Aug 14, 2007
    Posts: 10,561

    from Missouri

    Do the spark test as stated then pre heat turn up the gas flow on your mig and go for it and then post heat so you can bring down the heat slowly.
  23. 34toddster
    Joined: Mar 28, 2006
    Posts: 1,481

    from Missouri

    I have a friend that arc welded a D 9 Cat back together after breaking a big portion of it not knowing how to run it. I thought he was crazy when I went to his farm and he was inside the ( I'm sure this is the wrong term) trans housing welding it back together with some type of special rod, that was around 1983, the damn thing is still running.
    I guess my point is..weld that puppy, what do you have to lose!?
  24. I found these on a search (ebay)

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  25. depends on the cast iron etc...same for me....I have successfully repaired Chevy manifolds with a MIG and NEVER had a problem once back in the car and had MANY MANY miles on them...I use regular 030, no issues, I also have welded cast iron with an arc before, also with success..I did hear of heating up the cast iron then welding but I didn't have anyone to help me, so just plain welded it in both cases (arc and mig)

    I hear that cast iron methods and material changed over the years and where it came from etc

    p.s. cool tip from oldolds! I never heard that before - again I am guessing it must signify the make up of the manifolds, guessing certain materials act a certain way when they meet the grinder
  26. blowby
    Joined: Dec 27, 2012
    Posts: 7,275

    from Nicasio Ca

    I welded a broken mounting flange under my wife's toilet (yes,she has her own) with mig and standard wire. So far she hasn't fallen off it.

    Did a broken ear on a mill with a stick welder, nickel rod and lots of pre and post heat.
  27. Yes, Washington Alloy makes a wire for mig use. About $85.00 for 2 lbs.
    I have been doing miles of weld lately practicing welding cast for a project coming up. Although I am good with mig, it seemed like stick was the way to go. Using nickel 55 rod I have had good results and that is what I'll use because it's a sure thing.
    Most of the time I have not had regular mig welds crack either when processed correctly. Heat the part to about 450 degrees, weld shorter beads about 1 1/2" or so, then quickly peen the hot weld with the pointy end of your slag hammer (thoroughly). Keep the part hot through the entire process. When done, transfer the part to a steel bucket and fill with sand.
    Wait until cool (hours) and little chance it will be cracked even with mig. If you used the nickel rod, no cracks.
    Obviously cleaning an grooving the part (preparation) is required.
    Good luck!
  28. terryble
    Joined: Sep 25, 2008
    Posts: 541

    from canada

    V groove, preheat, mig weld (no special wire) and immediately wrap in insulation and don't look at it for twenty four hours (it should still be very warm to the touch). I have done several cast pieces (water necks, manifolds model T head) this way with about 99% success.
  29. G-son
    Joined: Dec 19, 2012
    Posts: 711

    from Sweden

    Clean, U-groove, O/A-weld with alot of pre- and post heat, use old cast iron piston rings or cast iron rod for O/A welding as filler (not nickel rod for MMA or something like that), pack in insulation for a very slow cooldown.

    This way you get at 100% cast iron piece, so no cracking risk due to diffrent thermal expansion or such.

    I would not use brazing. It's a good method for cast iron, but since it begins to loose strength already at a few hundred degrees it's not very well suited to use on something that will get alot hotter during normal use. Filling in a crack might be one thing, that might not even have any load on it in use, cutting, re-angling and brazing the manifold pieces back together will always put a pretty big load on the joint.
  30. I had a 48 Willys Jeepster with a 327. They fabricator used a right hand rear exit manifold on the left. it dumped to the front. That made the exhaust clear the steering box.

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