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Spark plug gap iquest iquest

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jeff w

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" Joe or Sparky,
On a 1973, 6

" Joe or Sparky,
On a 1973, 65 HP Johnson, Champion ( their gap ) recommends for the QL-77-JC4 to be .030
In the actual motor owners guide book, it recommends a UL-77V, is the QL-77-JC4 equivalant ?I see where the original owner made a note to gap at .038 for this same plug. What gap would you recommend ? Stay with .040 ?
Also, since the age of this motor was designed back when there was " leaded " fuel , would you recommend adding in the lead substitute additive that you can buy at any automotive store or stay away from the additive?

p.s. This is one of the best message boards I have ever read involving solving boat motor problems, etc. and I enjoy reading up on your recommendations, talk about excellent marine information ! What people can learn from this site, is priceless !!!!!!!!!!

Jeff, Daytona, Fl. "
 
I would stay at forty because

I would stay at forty because you will have less fouling that way. You don't have to add anything to increase lead todays TCW-3 oil and 87 octane gas will work good in those old engines.
And the QL77JC4 will work just fine
 
I don't disagree with .040

I don't disagree with .040 but it has been my experience that .035 works best for trolling and high speed...Plus as the plug wears your gap increases anyway..
 
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