1958 Seahorse Fuel Mixture

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  • September 13, 2015 at 10:28 am #23738
    wiscoboater
    Participant

      The electric starter and bracket on the 18 is a very sought after item. If anything ever happens to that motor, save the bracket. Many guys on this site looking for those!

      September 13, 2015 at 11:31 am #23739
      billw
      Participant

        US Member

        Mercury trained the techs to push higher octane fuel, not for the octane; but because it supposedly had more detergencey. Even 89 was better than 87, according to Mercury. They were trying to keep the rings from sticking, which was a problem with all outboards in the 80’s. The Tower of Power Mercs were quite susceptible to it; as were the OMC cross-flows and Force engines. I am not smart enough to know how true this detergency thing is, for sure. It is only what they trained us to do. Lord knows they were smarter than us. I have used 89 in everything I own for years and have never had a fuel related power head problem. No Quick-Kleen or anything; just 89. (Carbs are a different story altogether; although I rarely have carb issues, either, after their one first cleaning.)

        Long live American manufacturing!

        September 13, 2015 at 12:58 pm #23745
        fleetwin
        Participant

          US Member
          quote Mumbles:

          quote Chris_P:

          16:1 for the 7.5hp
          24:1 for the 18hp


          Exakery! The 5.5 and 7.5 horse motors have bronze sleeve type (friction) bearings on the crank and rods which need the extra oil while the ten horse use a combination of friction and needle/roller bearings while the eighteen horse and larger used needles and rollers throughout. Using a good brand of TCW III rated marine oil at the proper ratio instead of the motor oil suggested back in the fifties will help ensure the motor will still be running for your grandkids to enjoy!

          Can’t say it any better!
          PLEASE ignore all the advice about using less oil on these engines! Yes, today’s oils are better, but not enough to allow using anything less that 16:1 on your bushing engine! A well tuned/adjusted engine will not smoke much at all, even at 16:1!
          Enjoy your beautiful 1958 Johnson, please check change the gear lube before running the engine. You should also consider replacing the water pump impeller unless the seller can confirm it has been replaced recently.

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