Hot take: most people don't know how to gap a spark plug right

I keep seeing posts in here where folks slap a new plug in straight out of the box without checking the gap. I did that once on my old Farmall tractor from 1958 and it ran like garbage for two weeks until I finally checked it. The gap was off by almost 0.015 inches from what the manual called for. After I fixed it with a wire gauge and a gentle tap on the concrete floor, the thing started on the first crank. Why does everybody think new parts are always set perfect from the factory? I've found gaps off on plugs from three different brands just this year alone. Has anyone else had a plug cause weird misfires just because the gap was wrong?

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margaretk891mo ago

Wait, have you actually measured the gap on a brand new plug lately? I bought a set of NGK's for my old truck last spring and three out of eight were off by more than 0.020 inches. I always check every plug now with a wire gauge before I even think about threading them in. It takes like two minutes and saves you from chasing a misfire that makes no sense. A gentle tap on a hard surface or a flat screwdriver blade to nudge the electrode works fine, just go slow and check often.

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