Block Drain Petcock Tap

Tried to work it, the handle broke off, may have been weak from somebody’s previous attempts.


I drilled and extracted the broken threaded piece. A propane torch loosened it nicely.
It seems to be either 7/32"-28 BSF or 1BA thread. Neither seems promising to find a replacement, unless this handle thing is common in the UK?
#12-28 UNF is pretty close, but even in the USA that size is non-preferred and almost non-existent.
This seems to me like a weak design anyway, a stress concentration at the thread root. I’m thinking about tapping it out to 1/4"-28 UNF thread, for which I can easily get a brass bolt and make into a suitable handle.
Anybody see anything wrong with that idea before I proceed?

Who will know? Formed properly, it’s an invisible fix… and it saves the major parts, that are visible.

I think you might find Paul Beck vintage Supplies sells replacement that look just like that. They were generic , not S specific

Is there a reason the handle has to be threaded and screwed into the petcock? Couldn’t you drill the female threads out and if necessary, turn the end of the handle down a bit so it’s a snug fit in the hole, and braze it in? It would likely end up way stronger than it was originally. Brass brazes super easy. You’d lose 1/8" or so of leverage from the slightly shorter lever is all.

Or, silver solder… on stuff like that, it’s a bit more user friendly.

Yup, that’s brazing right? At least a brazing filler. The stuff I use melts around 500 or something.

Not quite, finished colour is actually silver rather than brass.

Yes, that was the other idea I considered, and in fact the one from the radiator seems to be brazed.


Paul Beck does not have this specific model with the down spout, but a number of others if it comes to that.

Paul becks part no 341 has the curved down outlet with a 1/8” BSP thread
I find the main cause of failure is the spring corroding.

1/4-28 is not a tapered thread, most liquid fittings are other than brakes.

Straight thread, that diameter is likely to shear upon tightening when attempting to seal.