09-12-2021, 06:58 PM
They are neither. They are 3/4 diameter 14TPI whit threadform.
A parallel 1/2 BSP tap, would clean the thread out nice, but the whole kaboodle would be bigger requiring a new plug.
I've got a lot of 14tpi whitform threads on my steam roller, which is 1920. It is alledged that the 14tpi tooling was to some Great War ministry naval standard. I expect probably why Austin also had it.
I've had to beg, borrow and make tooling to suit when carrying out repairs.
A parallel 1/2 BSP tap, would clean the thread out nice, but the whole kaboodle would be bigger requiring a new plug.
I've got a lot of 14tpi whitform threads on my steam roller, which is 1920. It is alledged that the 14tpi tooling was to some Great War ministry naval standard. I expect probably why Austin also had it.
I've had to beg, borrow and make tooling to suit when carrying out repairs.