Welding cast exhaust manifolds

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Joined
Dec 17, 2008
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I want to redsign the exhaust manifolds on my nailhead what should i used for rod and is there any tricks. I have 2 sets of 401's i need to make them both exit in the middle. A huge thanks for any help!
 
Cast is tricky. Pre heat, post heat. Arc welding with Nickle rod is old school. MIG will work, but you still have to pre heat, and post heat. Really old school, you bury the parts in the sand after you weld and heat 'em up. They make a newer rod called NiCast. It works well too.
 
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I used Nickle arc rods, made for Cast Iron. Worked very well.
Any decent welding supplier should have them

You will stand a better chance if the parts are CLEAN.

Cast Iron can be welded with a MIG,
but the technique is absolutely critical.
Pretending it is mild steel won't work.

Depending on how much welding you do,
the gasket surface may need to be trued up.
 
I am going to cut the down pipe and reposition it for my car. So where it meets the head will not be touched. Will try the nickel rod thanks
 
the way i was told from an old timer pre heat to 450 deg than useing a nickel rod run a root pass kinda hot then with a little lower temp weld and every inch stop and peen out all the stress keeping the part at 450 then when done cool in ashes for 4 plus hours its a pain but workes for me could you make some tubular headers?
 
I got a buddy of mine that can weld anything but the crack of dawn and he uses the nickel rod and heat also. Had him weld up some 3-speed tranny cases,works good and lasts. Myself I've used brazing rod & torch to patch a crack in a manifold on my hobby stock,that seemed to hold up real good,just didn't look pretty.
 
What would work is 364 dual exhaust manifolds but they are hard to find. I need them close to the block so it misses the frame. I have t bucket side exhaust now but want to do some thing different.
 
One "problem" with Nickle rods, is that the color is entirely different than Cast Iron.

If you were going to paint the manifolds, or have them Ceramic coated, nobody will know.

Just bevel the edges before welding.
 
None of these suggestions will last. At some point they will crack.There is a guy who pioneered welding cast iron and he is the only one that will guaranty that it will not crack.
Dan Gesick (530) 343-8198. He is in Northern California
 
None of these suggestions will last. At some point they will crack.There is a guy who pioneered welding cast iron and he is the only one that will guaranty that it will not crack.
Dan Gesick (530) 343-8198. He is in Northern California

Wow, there is only one guy in the world who can weld cast iron? He must be old, cause I have seen 60 year old nickle weld repairs that remain un-broken.
 
I saw a i think 32 with a nailhead with a mcchough super charger with home welded exaust manifolds that were at least 40 years old. i am going to do the nickel weld, if i prep it right they will be fine. i just won't put my inpact gun on rattle or snap when tightening the pipes to the manifold.
 
Cast Iron has a very high % of Carbon, so if the part cools too quickly from a high enough temperature,it will become brittle. Preheating the part before welding, makes it cool slower. Same with burying in sand or wood ash, they act as insulation, so the part doesn't cool too fast.

Some of the cast iron repairs I've done are now over 20 years old.
If they haven't broken by now, I consider the repair successful.
 
Thanks for the help i will get them done and they will work. Will take your advise and cool them slowly that is easy i have a stove that i can set at 400 then drop it down in increments till warm Thanks
 

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