Custom Exhaust Headers - Mig Welding Exhaust Headers - Build Our Own Headers

We dropped the headers back in place and eyeballed the shape the tubes would have to take to mate to the collector. Notice how the tubes all bend together right by where the collector used to be. We cut out this section with the chop saw.
We dropped the headers back in place and eyeballed the shape the tubes would have to take
Minus the bends, we're left with what looks like a relatively easy transition to the collector. Time to connect the dots.
Minus the bends, we're left with what looks like a relatively easy transition to the colle
You could go out and buy some mandrel bends, which can run you $30 plus apiece, or you could do like we did and use the cheapest source of bends on the planet: a set of old, discarded headers. We unearthed a pair that look like they'd been dredged up from the bottom of a peat bog. We passed them through our chop saw a couple more times separating the collector and flange and again cutting the bends from the sections of straight pipe.
You could go out and buy some mandrel bends, which can run you $30 plus apiece, or you cou

Instead of trying to make it fit while the header was mounted in the car, we come up with a way to build it on the bench. To do this we welded some more scrap steel bar to the top pipe and the collector, effectively locking in their relationship to each other. Now we were able to carry the whole thing to our workbench and work in a more comfortable and unobstructed position.
Instead of trying to make it fit while the header was mounted in the car, we come up with
We used sections of the bends from the pair of long-tubes we cut up to piece together our new routing. We used a MIG welder to tack everything in place, starting with the bottom tube, knowing that we would be building the rest of the tubes around it.
We used sections of the bends from the pair of long-tubes we cut up to piece together our
It didn't take long before we ran into our first problem-we blew a hole right through the tube at one of the places where we were making a tack weld. No big deal, right? Think of it as an opportunity to practice filling holes.
It didn't take long before we ran into our first problem-we blew a hole right through the

Filling Holes
Welding is all about managing heat. You have to get the base metal hot enough to liquefy and join with the molten filler material, but not so hot as to burn right through it. This can be a very delicate balancing act because different areas of the same workpiece can require different techniques. Edges are especially susceptible to burning through because there's less of a heat sink at the edge than in the middle of a panel or tube-heat is more concentrated at the edge because there are fewer places for it to go. So, a heat range that will make a nice-looking weld on the middle of a panel can blow right through when you come to the edge. One way to fill a hole is to build up the surrounding area with extra filler material one pass at a time until you've created enough of a "bridge" to close the gap. To prevent creating holes in the first place, back off the heat as you come to the edge of a panel if you're using a TIG welder. With a MIG machine, you may want to stop the bead before you reach the edge, wait a few seconds for the weld to cool slightly, and add a couple of tack welds to finish.