AC Spark Plugs

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  • May 3, 2015 at 9:43 pm #1398
    chris-p
    Participant

      How do you guys like the AC plugs? I know the AC K 421 plugs are the cross to the J4Js. How do they run? May buy some NOS ones.

      May 3, 2015 at 10:51 pm #15278
      legendre
      Participant

        Champ J4J also crosses to the NGK B7S (Stock #3710) 😉

        (Probably not what you wanted to hear.. but it’s awfully hard to beat an NGK for just about any use.)

        May 4, 2015 at 3:19 am #15301
        rmhxruss
        Participant

          AC M42K is the number for J4J. We used them for years work good. AC’s are hard to come by these days.

          May 4, 2015 at 3:47 am #15302
          legendre
          Participant
            quote RMHXRuss:

            AC M42K is the number for J4J. We used them for years work good. AC’s are hard to come by these days.

            Any better than the Champs.. or the NGK / Denso?

            May 4, 2015 at 2:16 pm #15318
            The Boat House
            Participant

              • This reply was modified 6 years ago by The Boat House.
              • This reply was modified 3 years, 9 months ago by The Boat House.
              May 4, 2015 at 3:16 pm #15326
              Mumbles
              Participant

                The AC plug chart is located in the Members Only library on the green boards.

                https://www.aomci.org/members/library/AC.htm

                May 4, 2015 at 3:58 pm #15330
                rmhxruss
                Participant

                  M44C is the AC J6J.

                  May 5, 2015 at 12:38 pm #15374
                  The Boat House
                  Participant

                    quote RMHXRuss:

                    M44C is the AC J6J.




                    This is the set the NOS plugs I found.
                    I can find charts to cross reference from the early days up to
                    the 60"s but nothing for AC plugs manufactured today.
                    However if you search eBay AC plugs seem to still be being manufactured in the United Kingdom in the style and numbers
                    from the 50"s – 60"s.
                    Go figure.

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