31-07-2019, 07:11 AM
(This post was last modified: 31-07-2019, 07:13 AM by Bob Culver.)
The thread in the alloy is quite short. i vaguely recalled recutting one in place 55 years ago so had a look. Seems to be 1/2 inch BSP parallel. (Assuming it the one and that this thread not the original!) Some other car plugs seem to have used this and it looks the same as original. May not be easy to acquire now. A BSPT thread and and taper pipe plug tempting but likley to leak without thread tape. Must not intrude too far.