Hi everyone!
In the midst of a head gasket replacement on my series 3 XJ6.
While the head is off ive gotten around to replacing the head studs themselves too and am about to start putting it all back together.
before i do though i wanted to clean out the threads in the block that the head studs go to as some on here have suggested before.
i just wanted to make a post to ensure i get the correct tap, i believe the one i am looking for is a 7/16ths UNF tap but am not 100% sure on the matter.
Appreciate any help.
Thanks for your time!

 

7/16" 20 threads/inch
Rgds
David

 

And make sure it is a bottom tap, so you get all the way to the bottom of the hole. Start with a normal tapered tap to ensure the first few threads are engaged properly, but finish with a bottom tap.