Quick spark plug gap question

Hey guys, I want to check my outboard for a specific gap... I believe its 7/16's inch. I bought an OEM ignition tester that is measured in 10,20,30 increments, so I assumed I'd just use a ruler... but my question is, do I measure 7/16" from gap end to end? The reason why I ask is because the zero line written on the tester actually starts about another 1/16" before the end of the gap. I just am very unfamiliar with this method and want to know if a 1/16" is that critical to the test, and if it is, which reference to use, zero line or the very end of the metal.




Also, what should a good spark reading show? I know it must cover the gap, but should it be a constant spark line, intermittent, etc. ?

Re: Quick spark plug gap question

No, 1/16 isn't critical.
Measured end to end.
7/16 inch is 11,11 mm, so set it at 12
What you're looking for is a strong blue spark (dim the lights). A failed test will show no spark at all (not enough voltage to jump the gap) or a weak orange intermttent spark.

Re: Quick spark plug gap question

thanks saumon