Plug gap on the Johnson motors 1985 and 1988

user 21074 · May 18, 2017

I have read that old school of thought/factory gap years ago was .40 on plugs instead of the .30 that books call for.Some use .40 on engines that have some age on them.Any thoughts?

Stumpalump · May 18, 2017

Wide gap idles better. Small gap is better at top end was the reason for the change. You can also try the gap less plugs of similar vintage. They last forever but some claim they don't idle as well as the regular electrode plug. They work for great me but if you have the regular style plug then try both gaps or set in the middle .035 and call it good.

hc803 · May 18, 2017

I've always gone with .030 on my 87 Johnson and never had an idle issue that wasn't carb/old gas related. My .02...

DaleH · May 18, 2017

Years ago, for motors where the books said 0.028" gap, OMC changed their recommendation to be 0.030".

But wait for Pappy to chime in ...

Pappy · May 20, 2017

Dale is correct.

Plug gap on the Johnson motors 1985 and 1988

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Plug gap on the Johnson motors 1985 and 1988

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