I've got a Holley NH carburetor and the seat won't screw in. The old seat wasn't there. It has threads but they are too large. It is supposed to be a 1/4-32 tap size I believe. A 1/4 -28 tap screws in easy, the seat goes in all the way flush so the threaded part slides into the too large threads. I tried an old seat from another NH and it does the same thing. I've got all the parts, everything cleaned, brass plugs drilled out and tapped for plugs and if the seat won't screw in then I guess I have a really clean trot line weight. Any ideas?
I had an NH straight thru with the same problem, I bought a 1/4-32 tap and fixed the carburetor. No doubt someone tapped it 1/4-28 doing some sort of repair over the years.
1/4 - 32 taps and dies are all over eBay, Amazon and any place good machine tools are sold.
OK thanks Royce. I've got a set of taps but no odd sizes. I'll get one and give it a try.
Well no hardware store has a 1/4-32 tap around here, no good tool stores open on Saturday. I can order one, but I wonder if there is enough metal left? That 1/4-28 tap seemed to screw in, but it seems like the whole threaded section of the seat falls through. Would a tap act like a knurling tool for valve guides and restore the threads? I guess I could find another carburetor body but I wish I had checked this before I did a bunch of work on it.
If the hole is stripped out you can install a 1/4 - 32 heli coil. I just got a. Ew kit in the mail today for exactly this reason.
I had one that was like that.Ended up making an insert to fix it,but I wouldn't do it again.