1947 Evinrude Zephyr (4404) Spark Plugs

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  • August 7, 2020 at 9:38 pm #211116
    Austin Bourdon
    Participant

      I’m in the process of restoring a 1947 Evinrude Zephyr and was thinking about upgrading the spark plug wire ends from the original terminal rings to caps/boots. Has anyone done this or is there any reason (electrically) to not do this conversion?

      August 7, 2020 at 10:18 pm #211120
      Buccaneer
      Participant

        US Member - 1 Year (includes $3 online payment fee)

        As long as there’s no clearance issues with the front cover using
        boots, you should be okay.

        Prepare to be boarded!

        August 8, 2020 at 12:09 pm #211141
        Mumbles
        Participant

          There isn’t much room under the front cover on a Zephyr for clearance so you will want to run shorty spark plugs if you are going to use boots on the terminals. NGK plugs, with a screw on terminal, in either BM6A or BM7A would be a good choice as they are of the correct thread size and heat range. The screw on terminal will also allow you to use the original ring terminals to, if desired.

          These motors were known to occasionally catch on fire if they had a fuel leak and a spark jumped from the plugs ring terminal to the cover. Using shorty plugs would help to eliminate that problem.

          August 8, 2020 at 9:34 pm #211176
          joecb
          Participant

            US Member - 2 Years

            Yes … exactly as Mumbles suggests. I use the NGK BM7A on all my Zephyrs … they run good. Just be aware that the NGK screw terminal thread is metric , so you can’t just grab any terminal cap or nut and use it on these plugs. Oh’ another thing , be aware that with NGK the higher numbers are cooler heat range as opposed to our common Champions where higher numbers designate hotter heat range.

            Joe B

            • This reply was modified 3 years, 8 months ago by joecb.
            August 16, 2020 at 12:41 pm #211801
            Austin Bourdon
            Participant

              Thanks everyone! I got the shorty plugs and am in the process of changing the spark plug wires. Will share results when complete.

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