MTFCA Forum

These little petcocks are made from unobtainium. They are used in the early Kingstons, some of the Holleys and a few others. Most often the need is for the early Kingston 4 ball with the short inlet -- the one with the inlet half way up the chamber. They are always missing, broken or leak.

They are 1/16 NPT pipe thread. I have never been able to find drain cocks in this size and have wasted all sorts of time trying to get old ones to not leak. So Saturday night I made some.

First photo shows where they fit in the Kingston 4 Ball.

In answer to the question I will certainly be asked, "How do you form the tips?"

Answer: I grind the tips on my valve grinder, which is an old Snapon that I have made adapters for the smaller sizes needed for these sizes.

Thank you Stan.

Nice work, Stan.

I have two four-ball carburetors and one is threaded for the 1/16 pipe drain... which I do not have. However, I did found these:

https://www.deboltmachine.com/products/1-16-drain-valve. They are not correct, but I am sure they are functional. I have not ordered one yet as I am still looking, hoping to find an original, and/or keeping my options open. I like yours better.

: ^ )

Thanks,
I've seen a couple of those like you show. IMNSHO ( in my not so humble opinion =) ) the problem with them is that they are intended to seal with tapered thread but there is no hex to get a wrench on to tighten with so you are using a pair of pliers to tighten them.

Ah, I checked them out on the website and it looks like they have 7/16 flats to tighten them.

I think they are made for Model Engineer projects in England and they wanted about $25 each plus shipping. Anything tapered thread is expensive.

On the other hand, you can't lose the plug which you could do with the ones I made. With enough time I could make them so the plug would be retained even when loose.

I made some with drain holes on the side and and some with no drain hole. Guess why?? So you can whittle a little wooden plug if you by chance lose the drain plug.

Can't help it: COOL thread! 'Scuse me, wonderful thread.
Bless you all that who see that small! Dang. A valve grinder to taper. Too simple but who would've thought.
Brass get jambed up/embedded in the stone?
I know you could come up with the tooling to retain the plug. Hmmm, perhaps a non threaded portion near the handle and form or punch the body after install... ?
Too bad the drain on an M-3 is 1/8" else I'd be beggin'.
Thank you

There are lots of ways to retain the plug but I used 1/4 - 32 threads which should tighten up very well and not unwind themselves. It is also easier to whittle a plug if you do lose the turn plug and easier to send out a replacement.

Yes, the brass loads up the stone, even with a big glob of goop and a steady stream of coolant on the contact surface. I have the surfacer for the stone and a couple new stones so it will probably all outlast me.

Back to the shop. Back to the shop. Only 4:30 Saturday. Back to the shop.