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MG MGB Technical - Can I bend metal with a blow torch?

Hello,
The front pipe of my exhaust system sits kind of low and I'd like to bend it up a bit where it bends (does that make sense?). Can I do this by heating the area I want to bend with a blow torch? Is this sufficient? If it will bend, will it lose its temper? I'd rather not have to uninstall it, take it to a place to have it bent for me, then have to reinstall it. Thanks so much.

Alex
Alex

Alex. Much depends on what you define as a "blow torch". The real ones use gasoline and do not get very hot. There are also propane/air torches, propane/oxygen torches, acetelene/air torches and acetelene/oxygen torches. The most commonly used for bending pipes is an acetelene/oxygen (oxy/acetelene) with a "rosebud" tip. If it were my car, I would leave it to the nice professional to do. If you screw it up, it is your problem (and you have a rather good chance of screwing it up). If he screws it up, it is his problem and he will fix it. Ask around at your local mechanic's shops as to whom they would recommend. I was introduced to a fellow who is a real artist in exhaust systems, very well read and a world traveler. I almost look forward to exhaust system problems because it allows me to visit Wade and spend some time talking and learning from him. Les
Les Bengtson

Alex, When I bought a new exhaust system for my 69 roadster about a year ago, the pipes going in and out of the muffler were not at the correct angle. I used my oxy/acetylene torches with the largest brazing tip to heat the pipe enough to bend it. I did it on the car and was of course very careful not to burn the car. Keep the heat of the torch moving around the pipe as much as you can. You want to heat as much of the area you want to bend as possible but you can't stay in one place for too long because you will put a hole in the pipe. Have a fire extinguisher or a live garden hose ready just in case. Yes, I suppose the pipe would loose some of it's temper but I don't think it matters once you get it all bolted up. Good luck.
Dana
Dana

It is mild steel, so it doesn't have enough carbon to have any temper. Most muffler shops will do exactly this with oxy, to make things fit.
Ken R.
Ken Rich

Thanks guys, I'll have to find myself an oxy/acetylene torch. I actually got everything to fit without bending anything, but if you can visualize this, I had to lie under the exhaust system (the middle muffler to be more exact) and push it up while a friend secured the middle exhaust hanger. I hope this is ok and that nothing snaps. I figured it's all steel or iron (as the manifold goes) so nothing is too fragile.

Crossing my fingers,
ALex
Alex

Alex,
If you're still planning on using the torch to bend the piece, I"d suggest that you loosen the hanger again, and let the exhaust system hang back down, using your friend to gently and very gradually raise it up while you carefully heat the piece you want to bend. Heat it over as wide an area as you can, as directing the heat on only one place can cause the pipe to crimp as you raise the system into place. It sounds like there may be some strain on the system as it's supported now, you having had to 'bend' it into place. That could be bad for the exhaust manifold, possibly causing it to crack if the strain isn't relieved.

Good luck, Joe
Joe Ullman

I had this problem and solved it by heating about four inches of the lower half of the pipe, the metal which has to stretch, with an oxy/acetylene torch to the point where the pipe can be bent upwards without too much effort. For safety I put a heat shield between the pipe and the bottom of the car. It was quite easy really. The pipe will only kink if the top half, where the metal is in compression, is heated.

Maurice
Maurice Blakey

Alex,
Why not try your local muffler shop first? They should be able to do what you want to without any disassembly, and they have all the knowledge and torches already. If they screw up, it's on them, not you. I have had pretty good luck in the past going in and asking them for these kind of things. Might cost 20 bucks or so..
Craig
CraigP

This thread was discussed between 13/03/2002 and 14/03/2002

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