Does anyone know where I can get one of these. It was fitted to a Serk heat exchanger made in the 1970's? It should have a thread on the left hand side, but it has sheered off.
I presume you have removed the broken piece from the heat exchanger. If not, that is the first job. You then need to establish what the screw thread is. It is probably 1/4 inch BSP, which is 0.518 inch overall diameter by 19 TPI.
You may be lucky enough to get a ball valve with that thread on it designed for 8mm or 10mm copper pipe, but capable of being screwed in (wrapped in PTFE tape) if you remove one of the nuts.. What sort of pipe does it fit to? I doubt you will now get a fitting exactly like the broken one, but ones like these are fairly easy to get, and most big plumbers merchants, but probably not the DIY stores, will have them.
You've got a bit of a stub left - if you get another fitting (eg a 1/4" BSP female to male) you could possibly, with a bit of sawing and brazing, stick a new thread on it. It might stick out a bit further than the original.
Lets see if a picture from Flickr works: [image]<img src=http://farm3.static.flickr.com/2114/2050673272_1927f2ca82_m.jpg/[/image]
Evidently not, but thats the link to a pic to explain what I mean. I've tried to post the picture but have got fed up with this forum software and its unintuitive way of handling images. And it's bloody slow tonight.
Looks like a standard, old, radiator drain tap. Either try your nearest radiator repairers or even try a scrap yard, many lorries have/ had the same tap fitted to the bottom of their rads.
Thanks for all the help. I have been in contact with PJH Tractor restorations and am awaiting some information from them, but things look hopeful. Serck are still in business, and were my first port of call, but they only put the tapping into the heat exchanger, they did not supply the tap.