Richard Milhous
Well-Known Member
- Joined
- Aug 2, 2021
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- 173
An inductive pickup won't trigger consistently on a really weak spark. You're right it doesn't actually prove the spark is strong enough, but it's usually right and easier to use than pulling and ground the plug. At least if you have a 12V battery handy to power it.Visibly that will check for spark. But is it enough to fire across the gap under compression? No way of telling with a timing light.
Either gap a plug to 1/4" or 6mm or get a real tester like the one below.
...and you can always have current discharge without actual spark, if the plug is bridged or the insulator is cracked.