Wanting to clean up the threads on my 3.4 head bolt holes. Should I use a thread chaser or tap. And are they 11mmx1.5 ? A 12 seemed too big and 10 was too small. Thanks Rick

Think I found my answer. 11mm x 1.5

Use a thread chaser instead of a tap to make sure you don't cut any metal, but just get rid of the junk.

You can turn an old bolt into a thread chaser like this:

http://www.corner-carvers.c...203607&postcount=332

[This message has been edited by Will (edited 10-02-2019).]