Welding manifolds?

[Phreakish]

As I get closer to doing some ACTUAL work on my car (in terms of going faster), I've been contemplating a tbi/hybrid monstrosity of an exhaust, but will my little wirefeed welder work well enough to weld on the iron exhaust manifolds? How do most of ya'll do it? I can't afford to buy go-fast parts out-right, so I gotta build and hammer things together. I have a few ideas, but this is the first major hurdle.

[guyd_15]

MIG will work, I like stick on the cast parts.

[Phreakish]

stick welding?

I know a local welder, but hes not comfortable with cast iron parts, so he just doesn't do it... I want to modify a TBI manifold, and not too much, but he still doesn't want to do cast.

What kind of wire and gas would work well with cast? Right now, we usually run just C02 and .027 wire (not sure what my friend picked up). Works okay for non-structural and fabricating not-so-great parts, but if Imma do a manifold, its gotta work...

[Pat]

A buddy of mine just removed a tbi header he had on a Shelby Lancer. He had the header/manifold, swingvalve and downpipe. He did all the fab work himself. It's a nice piece and I'm pretty sure he's selling. If you're interested in getting more info, I'll get his email addy for you.

[Turbo Joe]

well, the right way is to use a flame spray torch with nickel powder, to weld castiron. some guys use nickel rod on an arc welder though you have to preheat and keep it hot then slow cool the part.

[JDAWG]

heat up the metal first as much as possible with a torch was how i was taught, well for a kinda backyard kind of way

[contraption22]

We mig welded a stainless flange to my TBI Header and it held together for 6 years.

[Wink]

The mig will work. But it's not highly recommended. I've found that if you use an ARC welder with the proper, high nickle or "cast" rods, then you'll achieve better results. The trick is to pre-heat the cast iron part. Then, when you weld, try to keep the most heat on the cast. I use a drag technique. Keep the weld on the cast until a nice pool develops. Then drag the pool towards the flange. And when you're done welding, make sure to cool the assembly extremely slow. I recommend having a metal bucket with "clean" sand in it. Place the manifold in the bucket of sand, covering the manifold completely. This way, the sand will act as an insulator, and keep the heat on the manifold as it cools. If you don't allow the assembly to cool slowly, the cast will crack due to it's different heat retention compaired to the flange's.

[Phreakish]

all sound like great ideas guys! thanks!

I'd be willing to buy a header and such, but like I said - too poor to do much but fabricate it myself I also have a few other ideas to try out, but until I get down to it, its hard to describe...

I might practice on some spare manifolds I've got, using the mig welder... Just need to keep the oxy/acet torch on it to keep heating it huh? Time to cut me a flange...

[contraption22]

The mig will work. But it's not highly recommended. I've found that if you use an ARC welder with the proper, high nickle or "cast" rods, then you'll achieve better results. The trick is to pre-heat the cast iron part. Then, when you weld, try to keep the most heat on the cast. I use a drag technique. Keep the weld on the cast until a nice pool develops. Then drag the pool towards the flange. And when you're done welding, make sure to cool the assembly extremely slow. I recommend having a metal bucket with "clean" sand in it. Place the manifold in the bucket of sand, covering the manifold completely. This way, the sand will act as an insulator, and keep the heat on the manifold as it cools. If you don't allow the assembly to cool slowly, the cast will crack due to it's different heat retention compaired to the flange's.

What will happen when the manifold is on the car and it is repeatedly heated and cooled?

[2.216VTurbo]

The mig will work. But it's not highly recommended. I've found that if you use an ARC welder with the proper, high nickle or "cast" rods, then you'll achieve better results. The trick is to pre-heat the cast iron part. Then, when you weld, try to keep the most heat on the cast. I use a drag technique. Keep the weld on the cast until a nice pool develops. Then drag the pool towards the flange. And when you're done welding, make sure to cool the assembly extremely slow. I recommend having a metal bucket with "clean" sand in it. Place the manifold in the bucket of sand, covering the manifold completely. This way, the sand will act as an insulator, and keep the heat on the manifold as it cools. If you don't allow the assembly to cool slowly, the cast will crack due to it's different heat retention compaired to the flange's.

Neighbor has a really sweet TIG and it only costs me a 12 pack of Silver Bullet and he will weld anything I want What kind of rod for a TIG set up, is there high nickel stuff for TIG? TIA

[Ground Rat]

Time to cut me a flange...

What are you using to cut the flange?

[shadow88]

Really, I'd just buy the one that fwd performance is selling. It looks to be a quality peice.

I used a 1/2" plate of mild steel, I met a tool and dye machinist and did some repairs on his car in exchange for him making the flange for the turbo. He did an A1 job on it.

Word of advise- pre-install the studs with threadlock before welding so the weld doesn't back fill the holes. This is why I went through 2 manifolds and flanges before getting it right.

I also used a mig welder, starting with small welds around the flange-to-manifold mating surface to try to keep warping to a minimum. a little pre-heat and i welded about 3 inches at a time and got the torch back on it to help heat it up again and moving away with the torch slowly to allow it to cool. plan on spending 20 minutes per 3 inch weld.

Cut of the old manifold with a cut off wheel or sawzall, or bandsaw (preferred). Don't use a torch, it just puddles and sparks and blobs.

Although I"m aware that I should have used an arc welder rather than a mig, it's so far so good. I may have to re-do it when or if it breaks.

[Tony Hanna]

I'm going to build a pre/post heat setup for welding cast. Pretty simple really, just a metal box full of sand sitting inside an old gas grill. Preheat the part(s) to desired temperature, weld, then return them to the sand box to post heat and cool by slowly lowering the flame in the grill.
If you know the temp your material needs to be pre heated to, you can buy temp sticks at any welding supply shop that will let you tell when you've reached the desired temperature.