What size fitting is needed for the spark plug hole on a 99 Integra to do a leakdown test/ compression test. I only have seen two, 14mm and 18mm. I use a 16mm socket to remove the spark plug, so I'm confused!

Can someone help me out?
thanks

 

14 mm diameter threads. Your plugs have a 19 mm reach and 16mm hex on the outside to remove them.

 

thanks for the fast reply