spark plug gap

[pedixon]

Hi all

Just bought a 1990 4hp deluxe Johnson and Im going to put new plugs in.The generic Clymer manual I have says Champion L77JC4 .040 gap. Is this correct. This manual calls for same plug and gap for my 1989 15hp Evinrude,but my owners maual says .030 gap, so Im questioning the gap the Clymer says. This little Johnson seems to run good, except it will die at idle after a few seconds if you take your hand off of throttle. The plugs I took out are Champion L77JC4 gapped about .045.


Phil

 

[JB]

Re: spark plug gap

It will work with any gap from .030" to .040". OMC waffled a lot on gaps and you can find published specs for either gap.

Current thinking among the gurus here is that the hot ignition in that outboard can fire .040" just fine and the risk of fouling is reduced, particularly at trolling speeds.

 

[bktheking]

Re: spark plug gap

Champion chart calls for .030, manual says .040, run it at .030 and see how it runs, it won't hurt anything. Or run .040 to reduce fouling, either or.