Thread size NH Carb

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Model T Ford Forum: Forum 2015: Thread size NH Carb
Top of pagePrevious messageNext messageBottom of page Link to this message  By Micheal Crowe on Wednesday, June 03, 2015 - 07:11 pm:

What is the thread size of the where the bowl plug screws in?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dan Treace, North FL on Wednesday, June 03, 2015 - 07:45 pm:

The larger thread 9/16-24 is in the iron boss of the carb base for the drain plug assembly.

The little drain valve needle is 1/4-32.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Micheal Crowe on Wednesday, June 03, 2015 - 08:00 pm:

Thanks Dan


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Jelf, Parkerfield KS on Thursday, June 04, 2015 - 01:48 am:

What about the needle valve lock screw and the spray needle? We should have all the sizes here for reference. :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dan Treace, North FL on Thursday, June 04, 2015 - 09:55 am:

Steve

Here you go:

Spray Needle Valve Lock Screw (top hex nut) and Gas Inlet Elbow are 1/8 NPT. (Pipe thrd.)

The Spray needle valve is 1/4-32

The Float needle valve seat threads are 1/4-32.

The Spray Nozzle is 3/8-24


Top of pagePrevious messageNext messageBottom of page Link to this message  By Stan Howe Helena, Montana on Thursday, June 04, 2015 - 09:57 am:

The needle valve is 1/4 x 32, same as the float valve seat. The needle valve lock screw is 1/8 NPT (pipe thread), the same as the inlet.

I don't think I've seen a drain valve needle supplied by Ford or Holley that is 1/4 x 32, I believe they are 5/16 x 16 or 1/4 x 20.

Some of the reproduction drain valves do not work because they are not threaded deeply enough for the stop cock to screw far enough into the seat to shut off the drain passage.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bill Harper - Keene, NH on Thursday, June 04, 2015 - 10:20 am:

Does any one know the thread size of the pack nut or, another way of asking for the same info: the size of the inlet elbow at the pack nut end?

Thanks in advance, Bill


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dan Treace, North FL on Thursday, June 04, 2015 - 12:07 pm:

Stan

Thanks, was wrong on that needle drain valve, 1/4-20 is what I have seen.

As for the pack nut Bill
the pack nut is 1/2-18


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bill Harper - Keene, NH on Thursday, June 04, 2015 - 12:17 pm:

Got it, Dan. Thank you.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dennis Sanford - Lucas, TX on Thursday, June 04, 2015 - 01:32 pm:

Dan,
Can you edit the diagram and add these thread sizes to the diagram so that the information is all in one place?

Thanks for posting this information.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Stan Howe Helena, Montana on Thursday, June 04, 2015 - 02:48 pm:

There are a lot of odd threads on carburetors. Almost every one has some odd threads. Most common of the odd ones (if that makes sense) is 24 tpi and 27 tpi. Also quite a few 32 tpi. But the pack nut on early Kingstons vary either 1/2 x 18 or 1/2 x 20. Some pack nuts are 1/2 x 24, some are 9/16 x 18, 20 or 24 tpi. Stromberg liked 24 tpi, Zenith 27 tpi and Schebler 27. Some of the carbs like U & J were built on metric specs so they have some metric threads and some Imperial Machine sized threads. I have about 50 different taps and probably a dozen non-standard dies. Most are made in China now, the old ones are hard to find and surprisingly enough, hard brass or Silicon bronze wears them out in a hurry. Even the better quality ones don't last long, especially if you are threading in the lathe. Oil helps.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dan Treace, North FL on Thursday, June 04, 2015 - 03:07 pm:

OK That was fun, thanks Stan for the help. That needle valve drain plug is 3/8-20, checked several on hand. Thought 1/4-20 was too small:-)


Here is the rev with thread sizes by the part descriptions, found in Word/Paint there is a text function....so this is better.




Top of pagePrevious messageNext messageBottom of page Link to this message  By Dennis Sanford - Lucas, TX on Thursday, June 04, 2015 - 06:37 pm:

Dan, Thanks for adding the thread sizes to the diagram.


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