I’ve had a look at four barrels with cylinder wall oiling, three blindhead, and one detachable head type, and they are all threaded 9/32″ @26 TPI, which in engineering terms is a “Non-preferred” thread. Be very careful if you have to remove the hollow threaded studs from your barrel, as being hollow, they are rather fragile, but they can be unscrewed. Finding a couple of 9/32″ half-nuts to lock onto the studs in order to unscrew the studs, will not be an easy matter, and perhaps the best thing you can do is buy 9/32″ X 26 TPI taps from Tracy Tools, and then tap a couple of 1/4″ nuts out to the 9/32″ size, rather than spending days trying to track down some 9/32″ nuts. If you also buy a 9/32″ split die you could soon make a couple of new studs, but if you haven’t got a lathe boring the oil feed hole through them will be tricky.Why on earth didn’t the factory make it all in 5/16″ size !? It would have been stronger and easier to overhaul…
Brian
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