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Anyone have any idea what the difference is between a QL78YC and a QL77JC4 champion spark plug? (besides the numbers) My motor calls for the QL78YC plug but I noticed it has QL77JC4 plugs in it now. Would this cause the motor (98'evinrude intruder) to perform differently?
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I run a 92 intruder that originally called for the QL77JC4 champion spark plug. A few years later OMC changed their recomendation to the QL78YC plug for my motor.
They might have done the same for all the motors with those plugs perhaps, I don't know. But just guessing I wouldn't think there could be much difference.
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I'd rather be catchin! :7
dont have my chart at hand but they are different heat ranges and maybe it had to do with performance or was causing piston problems