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What the plug?

Discussion in 'Hangout Lounge' started by Stumplifter, Jul 28, 2017.

  1. Stumplifter

    Stumplifter Well-Known Member

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    Off topic, but quite confident I will find an answer here...

    Trying to resurrect a Weed Eater BC3100 that was 'donated' to me. Noted that the manual calls for a RCJ6Y spark plug, currently there is an RCJ8Y in it. Research indicates that the 8 runs "hotter" than a 6 and can be substituted.

    What do they mean by "hotter"?
    How does this effect starting/ running/ fuel consumption?
     
    Stumplifter, Jul 28, 2017
    #1
  2. JeffK

    JeffK Well-Known Member

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    Just refers to the plugs' heat dissipation rate... will start and run identically...no difference in spark voltage or intensity or the other myths.....but the hotter plug will retain more heat then the colder plug which will shed the heat faster....I've told people before to think of it like a radiator...both will flow the identical amount of water but one will shed more of the latent heat and will run cooler...hope that makes sense Stump

    jeff
     
    JeffK, Jul 28, 2017
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  3. Stumplifter

    Stumplifter Well-Known Member

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    Well heat and vibration are generally the demise of all things mechanical.... I should go cool.
    Or is it insignificant enough that it really doesn't matter?

     
    Stumplifter, Jul 28, 2017
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    REUBEN likes this.
  4. Rooster53

    Rooster53 Well-Known Member Premium Member

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    I think this may be quite common as I came across a similar issue in a Craftsman string trimmer which had an 8 installed from the factory but specified a 6 in the service manual. I wonder if it is not a misprint in the manuals that specifies which plug to use.

    From the below link:

    "The spark plug firing end temperature must be kept low enough to prevent pre-ignition, but high enough to prevent fouling. This is called “thermal performance,” and is determined by the heat range selected."

    https://www.ngksparkplugs.com/about-ngk/tech-talk/spark-plug-basics

    So is running the 8 vs the 6 OK? Yes, as long as there is not signs of overheating of the plug as indicated be excessive wear on the electrode or other signs of pre-ignition. Should you run with an 8? No, not if the 6 runs clean (insulator tip) and does not foul.

    Is the plug the issue with resurrecting? Not likely, most often the "ZAMA" carburetors are at fault for poor performance, and often times a complete carb can be found on e-bay for basically the same price as a rebuild kit locally.
     
    Rooster53, Jul 28, 2017
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