The drain valve that holds the bowl on the NH carburetor is supposed to screw in here. But this carburetor sat with water in it for so long that there's not enough left of the threads for the fitting to catch. The thread size appears to be 1/2-24. There's no Helicoil made in that size. Before I bite the bullet and buy a whole new carburetor, I thought I'd see if anyone has a less costly fix for this.
Braze it. Bore it. And tap it?
If you cant do it that way, how about, file some off the bottom re-cut the slots and take some off the bowl where it fits up to the casting. You would have to keep every thing lined up but could work. BTDT
The thread that you need is: 9/16 x 24 good luc
The threads don't look sooo bad. Could half the problem be the brass drain valve? Would trying another work?
I'm with Jerry, those threads don't really look that bad. A new, or different, drain valve might be the ticket!
Steve,If you don't have the tap,I do. I will tap it for you if you send it here and pay shipping back.
Probably cost less to just buy the tap. I think they're about $12 or $13 for a 9/16-24. Shipping a carb both ways would cost that much and take about 10-15 days.
Wouldn't you have to use a tap that is made to cut threads to the bottom of the hole. I would think that because of the taper of a normal tap, it would not clean much of the threads.
There's enough room to run tap in far enough to get good threads.
Thanks. That works.
Mark, that would be a "bottoming" tap, and are as easy to get as the tapered ones at places such as Fastenal or McMaster-Carr, etc.