O2 bung tap

[waskier01]

I've just finished welding in a new O2 bung and need to tap the threads.  I don't have the right tap, anybody know the proper tap size?

[Don D]

Try 18 x 1.5 mm

[Mike52]

Before buying a tap, you can use a spark plug thread chaser available at any auto parts store. I borrowed the proper tap from a tech at work only to find out the spark plug thread chaser I had in the tool box worked better.

Mike