Spark plug threads

[Jonny69]

Does anyone know the pitch for 10mm and 14mm spark plug threads? Looking to buy a tap for each, handy if I can use my existing NGK BP6ES plugs which are 14mm.

 

[Jonny69]

Will they do a new thread in steel though? I just dug out one of my 10mm plugs and it looks like it's a shade over 1mm, so probably 1.25mm. Just going to stick a vernier on it to check...