Tacho drive pinion blanking screw

Asked this years ago so somewhere on here is the answer…

What size thread to blank off the tacho drive pinion on engine casing?
Vague memories of a Vauxhall sump screw?!?!

Well it will be the same thread as the tacho drive outer that screws in there. In theory, being alu I would expect the thread to not be fine - so std metric of whatever dia it is.

Either ways, I have one in Blue (a plug not a tacho drive) and it’s due out into the light at the weekend for a final check before MOT so if I remember I’ll have a look.

M14 x 1.5 rings a bell,
(put one in mine about 10yrs ago, memory is not quite what it was)
Ps about 20mm long