1550 gas manifold

Mike(NEOhio) · Jan 14, 2016

I'm trying to clean up the threads for the muffler pipe. Can somebody tell me what the thread size is? I was thinking 2" NPT but it seems a little smaller than the 2" nipple I have. I have a pipe from an E-4 that looks like it would fit but the threads are damaged so that it will not start in.

fastfarmall · Jan 15, 2016

Not sure what size it is, but the tap will turn hard, i tried to clean one up on a M, i had a 6 foot pipe of there and did very little to restore the threads. The manifold is on the tractor right!

J. Schwiebert · Jan 15, 2016

2 inch. Fast farmall is right.

Mike(NEOhio) · Jan 15, 2016

Yes, on the tractor. I've been looking for a 2" pipe tap but they are hard to find. I tried cutting flutes in a 2" nipple but they will not cut. Guess for now I'll leave the short pipe that PO had wedged in there.

Mitch Poindexter · Jan 16, 2016

I use a drimmel with a cutoff wheel on it and walk it round and round in and out of the threads. Doesn't have to be on full speed. Once you get the rhythm figured out, you can clean up some threads in a hurry with it. Even if you don't own one, you'll be able to buy it at the hardware store cheaper than a 2in pipe tap, and it will be a darn site more useful.

Traditional Farmer · Jan 16, 2016

Part of the old pipe is still in the threads most likely a grinding wheel and a stiff wire brush will help clean them out.With a pipe tap you can only go a little at a time.You should be able to find a pipe tap on ebay,I bought one new about 20 years ago and it was around $50.Also a torch will melt out the steel pipe that's left and not hurt the cast manifold if you don't get too carried away.

rankrank1 · Jan 16, 2016

I will second Mitch's recommendation of using a thin fiber cut of disk in a dremel tool. I repaired the manifold on my Farmall m this way and it was pretty easy really. Used a dremel to carefully cut away any remaining old nipple pipe that had rusted into the manifold threads then used an old an sacrificial nipple with relief slots cut in it as a final dressing tool (aka poor mans thread dress tool).

My experience is that whether you have proper tap or not you can only repair the threads that previously had the nipple pipe screwed into them. Exposed threads in the manifold seem to burn away over time. This is the reason I like to get that nipple in as deep as I can so that I can retain and protect as many of those threads that are still exist in the manifold. In my opinion it is worth the effort to salvage as many threads as you can within reason.

If no threads remain then it is braze or weld the nipple in time which is always my last resort.

Mike(NEOhio) · Jan 16, 2016

Good idea, Mitch. I have a Dremmel that I use quite a bit. Don't know why I didn't think of it myself. Nothing of the old pipe is in there. PO had a new muffler (wrong one) stuck on to a short piece of some rusty pipe that was ground on a taper and stuck down into the manifold. Loose, but it doesn't leak. Of course, he also cut a 7 inch hole in the hood for the muffler.

rankrank1 · Jan 16, 2016

As follow up to my first post and your recent reply: Once you get the threads cleaned up as good as they are going to get in the manifold and assuming there is still some exposed threads sticking up above the manifold when you tighten it; Then you can also trim a little on the pipe nipple to help eliminate that slop. This provides a fatter part of the threads on the nipple to better engage the worn threads in the manifold. You can continue shortening the nipple until the point that you run out ouf threads when it is fully tightened against the manifold tip. Just be careful not to go too much and try to force it in there as it can split the manifold if the interference is too tight and you over force it which is why I am saying work your way there by feel.

1550 gas manifold

Mike(NEOhio)

Well-known Member

fastfarmall

Well-known Member

J. Schwiebert

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Mike(NEOhio)

Well-known Member

Mitch Poindexter

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Traditional Farmer

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rankrank1

Well-known Member

Mike(NEOhio)

Well-known Member

rankrank1

Well-known Member

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