J8J spark plug

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  • March 13, 2019 at 12:48 pm #171118
    aquasonic
    Participant

      US Member
      labrador-guy wrote:

      A J8 is to warm for OMC motors.

      Not entirely true. My Johnson TD-20 owner’s manual recommends Champion J8J sparkplugs. Then again, they also recommended a 16:1 mix using 40W automotive motor oil, if you didn’t have the “Mobil” outboard oil. Maybe they needed the extra heat with that heavy oil.

      • This reply was modified 5 years, 1 month ago by aquasonic.
      March 13, 2019 at 2:08 pm #171120
      Mumbles
      Participant

        Hotter than factory recommended plugs are usually better for worn motors with lower than normal compression to help burn the fuel mix and help prevent fouling the plugs. Motors with high compression will want to use colder plugs.

        March 13, 2019 at 4:37 pm #171127
        garry-in-michigan
        Participant

          Lifetime Member

          Here is what I have –

          1949-Champion-Chart

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