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Spark plug fouling?


dentwizz

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On my 2010 with rebuilt engine and carb, new plug, new condenser and points, the plug seems to foul black rather quickly. It does not smoke. When it runs it runs well, but then the next time I try to use it the plug is black and no fire. Blast it clean and its fine for a while. Question is, why is this an issue? I have never had an engine black-foul in this manner so quickly that didn't have a smoke problem.
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Black or sooty spark plug usually indicates over fueling or a rich condition. Possible high float, or air/fuel needs to be dialed in a little better toward the lean side. HTH Steve
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High float could be possible. I set it as per the manual(parralell to the body) which seems high for a tractor in my opinion. I hadn't thought of that as a possibility. The high speed jet is about as lean as I can make it because if I go any leaner it goes unstable. Might this also be related to the lightly wet fuel sediment in the barrel of the carb?
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Quite a while ago when Briggs moved from J-8C to CJ-8 and then J-17LM to J-19LM. A lot of this transition came about because of no lead gas. In this transition there were complaints of plug fouling. In one of my Sten's part books Champion had Sten's insert a corporate letter that if the J-17 and J-19 plugs were fouling out , go to the CJ-14 plug and the problem would disappear. CJ-14's have been known to resist fouling. I have converted all my 4 cycle air cooled engines and the problem went away. If I get a fouled plug now , it is generally two or three years later, if that.
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That confirms what I experimented and found today. I had one of the afore mentioned replacements and it worked acceptably. Thanks for the data, that info will go into the manual notes.
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