Exhaust pipe threads

Dan-in-MO · Nov 23, 2012

A previous owner braized a piece of pipe onto the manifold. Needless to say, the braize didn't hold. I figured I'd put it back to right. Looking through online parts catalogs, I can see the exhaust pipe is threaded into the manifold. But my manifold threads are coated in a heavy layer of carbon. So I got 2 questions. 1.)What is the best way to clean off the carbon but preserve the threads? 2.)What size die do I need to thread the pipe?

Dan-in-MO · Nov 23, 2012

Oops. That's a '47 Farmall H. Gas only motor.

rustyfarmall · Nov 23, 2012

(quoted from post at 11:56:30 11/23/12) A previous owner braized a piece of pipe onto the manifold. Needless to say, the braize didn't hold. I figured I'd put it back to right. Looking through online parts catalogs, I can see the exhaust pipe is threaded into the manifold. But my manifold threads are coated in a heavy layer of carbon. So I got 2 questions. 1.)What is the best way to clean off the carbon but preserve the threads? 2.)What size die do I need to thread the pipe?

You need a 2 inch pipe tap. The re-threading will go easier if you burn away most of that carbon using an O/A torch. Use a brazing tip instead of the cutting tip. Just slowly wave the torch around inside and watch that carbon just sort of disappear.

Actually, if you can get rid of enough of that carbon, a new pipe MIGHT screw in without the need of the pipe tap first. I say MIGHT.

David G · Nov 23, 2012

Rusty, that is a great idea, thanks.

GordoSD · Nov 23, 2012

Cut a couple longitudinal groove in the pipe thread with an air hi speed die grinder,and it will help

Hayfarmer · Nov 23, 2012

If you get carbon off, you can take a short piece of 2inch pipe with threads on one end, Cut 4 groves with hacksaw across threads. It will act sort of like a tap. screw it in until it gets hard to turn, with pipe wrench, the back it off. Go further each time. May be enough to clean up threads. It is tough and expensive to find a 2 inch pipe tap. You don't want to get too tough with it or you can crack maniforl.

Dean Olson · Nov 23, 2012

In addition to other great ideas, I do all of them, + run a wire wheel on a drill to clean the threads out. I then run the tap.

Dan-in-MO · Nov 23, 2012

OK, so..... O/A torch, wire wheel and re-tap if needed with 2 inch pipe. Luckily, I have a btother-in-law who is a retired plumber. I'll see if he has the taps and dies still left.

FBH44 · Nov 24, 2012

I asked around and asked around and asked around, and all the plumbers and lumber yards and etc. said No 2" Tap. Fainally asked my friend (a machinist / blacksmith) if he knew anybody wlse, and he said Shooot we got a 2" tap, bring the manifold in. You might just keep asking around..

Exhaust pipe threads

Dan-in-MO

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Dan-in-MO

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rustyfarmall

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David G

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GordoSD

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Hayfarmer

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Dean Olson

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Dan-in-MO

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FBH44

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