How The Pros Do It.
We talked to the guys at Stainless Works, no strangers to making custom headers for unusual powertrain combinations. When faced with a one-off application, they start by bolting a flange to the exhaust ports, and mount the collector where they want all the tubes to meet. Then, they rough in the overall shape using straight tubing cut at angles and tack welded together. Once this "template" is complete, it's taken over to a machine called the Romer that scans the pipes and determines proper mandrel bends needed to assemble the header.
Stainless Works' Scott Harrison says they feel that this is the best way to design a set of headers from scratch. When you have a starting and ending point, it's just a matter of cutting the bends, and welding everything together. Stainless Works sells "you-weld-it" kits for a variety of applications for the guy who wants to build his own headers, but isn't interested in blazing new trails. Harrison also recommends that when you are planning to make your own headers, use stainless steel if you can afford it, whether or not you buy it from them. "It's a very time consuming process, and you want them to last once they're done," he said. We can attest to that.
Though not entirely successful, this was ultimately an exercise in welding something real. Recently, we've gotten some readers' email expressing concern of the tone of some of our "make-it-yourself" articles. Some readers may have gotten the wrong impression-we do not mean to imply that if you don't build every square inch of your car, you're not a true car crafter. Our intention all along is to show that there are a lot of things you can do yourself. It takes a lot of practice, but this is all stuff anyone can learn to do if they want. And the benefits are satisfying-you're constantly learning new skills, and you can stand to save a lot of money, too.
In addition to our chop saw, TIG and MIG welders, we could not have done this work without these additional tools. A good bench grinder is an absolute must. We used the wire brush attachment to clean up the areas to be welded. We also liked the electric angle grinder behind it. With a 36-grit flap disc attached, this thing removes a ton of metal in a hurry. Be careful not to grind through any areas like we did! Also essential was the right-angle attachment on our other bench grinder. We used that to true up any odd stuff left behind by the chop saw. If your can swing it, these locking pliers and a set of copper strips are also very helpful, though not necessary. Especially considering when tack welding sections of tubing together, you'll wish you had about six extra hands. The Eastwood Company sells these locking pliers specially made to hold tubing in place. The copper strips, also available from Eastwood are very useful when filling holes. Molten steel doesn't stick to copper, so you can back up a hole with one of these copper plates and weld until the hole disappears.
To make the headers we used a TIG welder almost exclusively for welding the tubes together, mostly because heat is easier to control than a MIG. You can use a MIG welder, however your weld beads will be larger than with a TIG machine. For both welding processes, we used ER70S6 filler wire, but we used pure argon as the shielding gas during TIG welding, while the MIG torch was blowing out a mixture of 75% argon, 25% carbon dioxide-standard stuff for welding mild steel.
You don't need a lot of heat when welding tubing. We had the TIG welder set at about 35 amps for most of the job, while the MIG worked best on it's lowest heat setting.