Tools & Fabrication - Welding cast manifold???

Have read the various posts about this procedure, and understand the basics.
I have 2 welders.. A TIG, and a MIG.
I have mild steel wire & stainless wire for the mig.
I have mild, stainless, and silicone bronze for the tig.
The manifold in ? is a 6.0 truck manifold that I had to mill off on 1 side, for steer gear clearance. [2x4" hole]
The hole has been covered w/ 1/8" mild steel plate. The manifold can be pre/post heated. I have temp sticks to control the heating.
Suggestions as to which welder and wire would be most likely to produce the best results, are appreciated.

I would like the tig for this application but either should work fine. However, if it is a shitty cast I think you will have trouble welding it decently. In the casting process, often times bubbles, or lots of them, are trapped inside the metal. Welding will release these. If its a good cast there may be little to no bubbles and welding will go quite smoothly, much like welding steel plate. If its a shitty casting, and there are lots of bubbles, good luck welding anything to it. It will literally bubble like the metal is boiling, usually ending up in one shitty weld. My .02.

Thanks for the reply..
So far, I've tried the following:
All tig. Weld w/ mild steel, no preheat. Heard it "snap", see no cracks.
Then, preheated, same mild weld. No cooling "snap".
Then welded a scrap to a junk manifold. No preheat. Snap. No cracks seen. I broke the scrap piece off w/ a pliers. The weld let go on the scrap part. Manifold held.
Did the silicone bronze and scrap weld, preheated. Looks good, and the scrap is not budging!

I may just go w/ the silicone, pre/post heat/cool, and call it "nice"!
Getting a set of headers to fit w/ an LSX in a 55 is a PITA!

Got'r done...
Preheated to 500* w/ a torch. Welded an inch, added heat.. repeated until I was at the point of tacking in the 2nd piece. Put it in a bucket, filled it w/ floor dry, let it sit for an hour. Temp was down to 80*. Welded in the last piece, repeated the cool down...NP. No popping, cracking. Off to the coaters!

Excellent, this is what my friend did for me, preheated the manifold and kept it warm throughout the process and tigged them up, they came out beautifully :)

Glad you got her figured out, post some pics when you get a chance

I haven't done anything with these GenIII manifolds but
good ol' 6013 rod was fine for me, welding O2 sensor
bungs into SBC logs.

hi,
the aforementioed is correct.......arc welding,brazing or tig with proper prep work which is a must. use a reputable welder and the correct repair materials.
good luck have a blessed day........jim

The absolute best way to weld cast iron manifolds is to fusion weld (Cast to cast) them. Although, arc welding will work, it can be difficult to weld right and get good results. Before having them coated, i would HIGHLY recommend either magnetic particle checking them, or use some form of dye penetrant to make sure it didnt crack.

I work at a company that specializes in cast iron repair, and we never arc weld cast iron. Ive seen too many parts that were ruined, because it wasnt done right.

Wasn't this type of repair done by brazing in the past? I don't think I even know someone who can braze :confused: TIG welders are freakin awesome, definitely versatile.

brazing would have been easiest most likely...

Ive had to weld large 3foot diameter cast flanges to mild steel and I pre heated with several torches, and used some ni99 rod from my supplier with decent results. I dont like arc welding it though, too many worries...

on semi turbo manifolds we used to pu them in a oven and get them red hot and then use a nickle rod to arc weld them it keps the shrinkage of the weld down . and you let it cool in a oven too .

well... i have no idea how mine held... i cut off the flanges and rewelded them just welded at large tack on 3 different sides and then welded the whole thing. no preheat, ran for 8 months with no cracks ended up selling the kit.

you could have just welded it with a flux core wire welder and saved you a bunch of time.

i used a mig to weld a plate on my v6 manifolds, held up fine

If it's a good casting then weld it with whatever you're the most comfortable with. The fact is the more time you spend futzing with it the more likely you are to have problems.

With crappy castings the only way is to braze it

for cast I like to use the TIG and Silicone-Bronze works great.

even if you get it to work,its just going to break off eventualy, cast sucks to weld,and hold welds period.

The real question is, is the manifold you are talking about
really cast iron, or something else like nodular / ductile
iron.

If it drills out like powder then it's cast. If it makes curlies
it's ductile and you can get away with a lot more careless
work.

Are you all welding V Band clamps on these manifolds or what?

yes, that is what they are doing.

If it drills out like powder then it's cast. If it makes curlies
it's ductile and you can get away with a lot more careless
work. i like this, never knew that.

I've been reading up on this myself lately. Several guys from the forced induction forum have done it and there's some good threads on it in there. Here's one that went to 4 pages. http://www.ls1tech.com/forums/forced-induction/1353102-welding-v-bands-truck-manifolds.html

I have welded broken manifolds by grinding a v grove then take an nickle arc welding rod, remove the flux coating, hit with a hammer and then use the rod as filler for a tig weld.

The two other guys that said use nickel rod are right. In maintenance that's what we use to weld cast elbows and tee to mild steel pipe with some preheat. The nickel will flow into the cracks that are left behind from the welding arc and heat driving out the carbon in the cast. Everything else will crack under pressure and stress.

Thanks for the reply..
So far, I've tried the following:
All tig. Weld w/ mild steel, no preheat. Heard it "snap", see no cracks.
Then, preheated, same mild weld. No cooling "snap".
Then welded a scrap to a junk manifold. No preheat. Snap. No cracks seen. I broke the scrap piece off w/ a pliers. The weld let go on the scrap part. Manifold held.
Did the silicone bronze and scrap weld, preheated. Looks good, and the scrap is not budging!

I may just go w/ the silicone, pre/post heat/cool, and call it "nice"!
Getting a set of headers to fit w/ an LSX in a 55 is a PITA!

just like the battery bunny!:D