I am going to be buying a couple of U pipes, along with some 2.25" tube, and will be building my own system of 2.25 dual into a flowmaster 2 in one out, with 2.50 single out the back. I will use the manifold flanges off the walker Y pipe and go from there.

I have a Mig welder and was hoping to get some tips. Should I convert to Tig?

I'm a novice welder.

 

Sounds like a good plan.

TIG takes a lot of practice for a novice welder to get the hang of. It's way beyond my skill level right now. I would stay with MIG for now.

The MIG welder will be fine for the exhaust work. If the welds don't come out looking too pretty you can grind them down to clean them up.

Practice welding on some scrap pieces of exhaust tubing.

When you are laying out your exhaust system make some orientation marks on both side of the seams. And tack weld the pieces together until you have the whole system laid out and fitted. Then pull it out of the vehicle and do all the final welding.

 

Absolutely buy some extra pipe to practice and get the machine settings dialed in.


If your pipes are stainless, you will lose the SS quality during the weld, unless you're familiar with welding SS and have a machine setup for it. Being novice, I doubt that's the case, but also keep in mind that it's not a huge problem. You'll just get rust buildup on the welds as time goes by. Again, not a huge problem.


If you're not comfortable with overhead welding, definitely tack it in and weld as much of it as possible out of the vehicle.


Unless you've got the money and the time to move to TIG, I wouldn't worry about it over something as simple as ONE exhaust system.

 

I'm a welder, and my standard advice is this: Wire-feed welding is the easiest way to make good-looking bad welds. Non-welders and wannabes all assume that a good-looking weld is a good weld, and this is far from true. You can have rather mediocre-looking welds that are sound, and vice versa. New guys always agree that they should take a two-night-a-week welding class and have a professional welding instructor show them what they need to know, but almost none will actually follow up on it. They always think that if their uncle or their buddy comes over a couple of times to "show me how," and if they watch a lot of YouTube videos, they can get "good enough to stick things together, I don't need anything fancy." Soon they think they are good enough to do their own welding on trailer frames and hitches . . . and maybe some innocent gets hurt or killed when the welds fail. Bad welding can have serious consequences. To outsiders, welding looks sort of low-tech, something practiced by barely-literate knuckle-draggers, where machining looks very precise and impressive and is practiced by skilled blue-collar tradesmen. But this is an illusion. I do machining as well, and where you CAN teach yourself to do precise work on a lathe or milling machine, with help from videos and books and friends, I have yet to see a self-taught welder that was any good. Actually, running the bead is about 20% of what you need to know. But I can never convince any newbie of this.

Take the night class at the local community college. Typically you can enter the class any time during the quarter, and buy two weeks of instruction if you want. Welding can be a lot of fun, a very satisfying skill to have, once you really know what you are doing. (End lecture).

You can weld your tailpipe with MIG, and certainly don't need TIG for this work. I always gas-weld my exhaust because it's the quickest to set up, and works just fine. FYI, many of the sharpest builders of homebuild light aircraft gas-weld their chome-moly tube fuselages, where it actually has a couple of advantages over TIG-welding, which also is used for this.

If you are using a no-gas flux-cored wire (technically this is GTAW, not MIG), get .030" wire for this job. And practice. With no-gas wire, when you blow a hole that you have to fill, try holding the contact tip much farther from the work (long "stick-out" of the wire). A mark of experience for a welder is not that he never blows holes, but that he is good at filling them when he does. When making butt-welds on thin tubing, spend whatever time you need getting a very good "fit-up," so you don't have big gaps to fill. If you have to fill a gap, try an on-off technique: weld for two seconds, stop for two or three seconds, weld for two seconds, etc.. One of the things you learn early is that making nice welds involves establishing a rhythm for manipulating the torch in various directions; the rhythm varies depending upon what you are doing, and it often is helpful to count out loud to yourself, even after you have welded for years.

If using a shield-gas and solid wire (this is MIG), ignore what the supplier may say and get a bottle of C15 (works for everything you are likely to do) or even C10, not C25, and .024" or maybe .030" S-3, not S-6, wire. The C15 and S-3 wire will tend to help you keep from blowing holes, esp. when going uphill.

I suppose your buddy-who-learned-to-weld-in-high-school can "show" you how to "stick things together" well enough that your tailpipes won't fall off and bounce off the shin of some poor motorcyclist. So go for it.

Or just clamp everything together like muffler shops do . . .

 

Wow, Smitty, did I touch a nerve? 'Me thinks thou dost protest too much.'

 

I do believe you did.
The guys i know are well aware of their welding strengths and weaknesses. They slowly increase their skills by welding non-structural items like exhaust systems, patch panels for floor rust repairs, building a welding table, etc. When strength is critical, they call in their fellow car guys that have a track record of high-strength, reliable welds. When they don't feel comfortable with their end product, they call for assistance. These guys are serious enough to buy their own mig setup and are eager to learn how to use the equipment correctly and do the job correctly.
Just my opinion.,...jack

 

Well, you asked, Restorer. I called it the way I've seen it over years and decades, and I hoped you would see that since I don't know you, I wasn't applying any of the critical part to you personally . . . unless it does apply, which only you would know.

Trade school welding instructors all see self-taught/buddy-taught welders come in from time to time. These fellows usually want to get some certification that they can hang on their resume when applying for a job. And they're always in a hurry. The instructor sets them up in a booth, gives them the materials for making the specified welds, and asks if they want some scrap to practice on. "No thanks, I know how to weld," is the frequent response. After which they completely blow the test.

One never quite knows how one's words will be interpreted, Restorer, and my intent was not to throw a wet blanket over your idea but to encourage you to take the time to get reasonably good at welding. Not only is it fun, as I said above, but the more welding techniques you pick up, the more you will ask yourself, "How did I ever get along without this?," and "How do even ordinary homeowners manage to keep things going without being able to weld, or have all the mechanical skills and all the tools I have to have??" Anyway, the more you learn, the more fun it becomes (and the less trouble you are likely to make for yourself).

Looking back, I do see how my reference to motorcyclists' shins looks like a snotty way to say don't even try. I didn't actually mean it the way it came out, and I really did mean "go for it." Sorry 'bout that, Restorer.

Jack, it seems you are seeing a smarter breed of cats than I am, so I won't argue the point. But think about this in relation to the new welder being "shown how" by even a highly-skilled buddy. In WW2, a lot of good gals went into the shipyards, etc., and were trained to make the necessary welds. But they were not trained to be professional welders. They were shown only what they needed to know. The work was all set up for them; they had no need of knowing anything about metallurgy, fitting, drawings, consumables, power supplies, or anything but what they needed to make the weld. At this limited task, they were very good (women have steadier hands than men, for one thing). Now, a hot-rodder who wants to weld in a patch-panel for a rusted floor-pan certainly can be "shown how," and become good at that. But then a neighbor brings him the broken handlebar of the dirt bike he ran into a tree; "I hear you can weld, can you fix this?" "Sure," say our buddy-taught rodder, who doesn't know that the handlebar is a strain-hardening alloy that can't be welded without introducing a heat-affected zone that will be a stress-focus, and that the repaired handlebar will be a lot more likely to fail in service (and if it does, will he be sued by the neighbor's wife?). This is the kind of information that formal training is designed to impart, whereas being "shown how" by a buddy is like those gals in the WW2 shipyards being "shown how" by a shop foreman, only imparting what is necessary for the immediate task. Therefore, I wouldn't say that this buddy-taught welder, though he certainly mans well, is "well aware of his various strengths and weaknesses;" he doesn't have the frame of reference to know, Jack.

 

all of these are very valid points to be made. like its been said, take your time, keep things plenty clean, practice on some scrap first. good penetration and sound quality welds are perfectly capable with a wall socket wirefeed. the metal is a heatsink...once the heat runs out of material to run to, it'll blow thru. keep an eye on your welder settings, gas pressure, and decent work cable (ground) location. grinding can help clean things up afterwards...i prefer a good flap wheel to smooth things out, but to each their own. before you know, you'll have buddies asking you to do their exhaust. just be mindful of any potential safety hazards, flammables, shorting electrical components on the truck, etc. and keep plenty of good ventilation in your work area. look forward to seeing pics once you post back up.

 

As usual the site automatically sent me an email alert that somebody had responded to the thread. But I think part of Dude's first line got omitted, because as shown in the email the first line included the info that Dude is "a welder and a CWI."

A Certified Welding Inspector is, ultimately, the bad welder's enemy and the good welder's friend. Welding has possibly the lowest opportunity for b******t of any profession because when you want to hire in to a new job, your resume and your interview and the rest means nothing . . . until they put you in a test booth and you have to Make The Weld, . . . which then has to pass the no-B.S. tests of the company's CWI. And on a lot of jobs, you have to keep passing those tests. A good CWI can teach you a lot about what you are actually doing as compared to what you think you are doing. Having learned via the humiliating experience of failing some tests, the good welder gets so he generally knows when everything is going in right, and when he has to grind it out and try again. Again, the instructor in your local tech school can give you a good start down this trail.

 

I'm not going to get into a debate over skill levels.

I just want to show my '46 pickup exhaust system (460) that I tack welded in place, carefully removed it, and finish welded it all around. I don't like muffler clamps for several reasons so I wanted a "one piece, fully welded" lifetime system. It is made from stainless steel (I bought a wheelbarrow full of Mustang V8 polished stinger pipes at a swap meet) pipes and stainless Flowmaster 50 mufflers but I welded it with MIG wire non stainless. Kinda what I think you have in mind.

 

1) i chose to edit the post and omit the info myself cause i didnt feel that my job description was nearly as valid as the guidance being given. you're right though, i'm not a very popular guy in some cases...fellas dont enjoy being told that their weld failed to pass. on the other hand, the code is law and is the standard. if they cant meet the standard, its my job to identify those short-comings to help mitigate potential safety issues in the future.
2) i dig the stainless. its really pretty but can also be ( and i'm sure i dont have to tell you this Flyer ) dangerous to weld without a respirator or at the very least, TONS of ventilation. do yourself a favor and look up hexavalent chromium. nasty stuff.

 

Thanks to FTF for the info. The exhaust project is in limbo. I have most of the parts needed for the conversion, muffler, efi mannies, tail pipe, etc., but I'm waiting to see if I'll have the vapor lock issue after switching to a Holley. In March we had several 85* days and I had zero issues.

Time will decide whether to go with dual 2.25" from the efi's, or from the header.

Question: When I look at the collector end of the efi, where the exhaust bolts on, there is a lip that over hangs into the flow. It would not hinder nor alter the mating surface of pipe to manifold by removing that lip, thereby increasing flow, so why don't people mention removing that as a performance mod.?