I've been reading a lot of threads regarding spark plug gaps and have tried gapping my 1989 300E @.39. The only concern I have is making sure the gap is square to the electrode. I've seen a specialty tool for gapping but is it worth it? I use the recommended coppers but I'm not sure if they are square after gapping.Will a off center gap effect performance? Any Comments? Thank you, Josie's Dad

JD I do not think that you will be able to tell if it does.
Jim
'95 E320
'97 CRV

Don't worry about this. As long as the gap gauge is the correct one, you will be fine.

I gap sometimes 50 or more plugs in a month, none if which are off center when done.

Thank you for your comments! Josie's Dad