Fuel mixture for old motor?

Discussion in 'Boat Tips' started by OkieBo, May 17, 2006.

  1. OkieBo

    OkieBo New Member

    Messages:
    199
    State:
    oklahoma
    I have a 1957 18hp sea horse johnson outboard. Is 25:1 the mixture i am supposed to be using on my old motor? Thats almost two pints for 6 gallons right?
     
  2. peewee williams

    peewee williams New Member

    Messages:
    3,111
    State:
    Pembroke,Georgia
    I believe the oil to gas ratio called for 24-1.=5.33 oz.to the gallon,or 32 oz.to 6 gallons.peewee-williams
     

  3. vlparrish

    vlparrish New Member

    Messages:
    1,276
    State:
    Bedford, Kentucky
    Okiebo, when that motor was developed, the ratio was rich because of the lack of good lubrication with the oils manufactured in that era. If you are using any of the well refined two-stroke oils now like, Pennzoil or Quicksilver I would go with a 50:1 ratio. This mixture of todays oils will give you plenty of lubrication and still burn hot enough not to foul plugs. Vern
     
  4. Iowa_Josh

    Iowa_Josh New Member

    Messages:
    1,463
    State:
    Central Iowa
    Okie, '57 is about the year before they invented bearings for outboard motors. I have the same one, same year etc. I took it apart and everyone was correct there are bronze bushings in everything. Seals weren't as good either so they used a lot of oil to help the mediocre seals to work. I believe 25:1 was for SAE 30weight non detergent oil. I think collectors use 32:1 modern two stroke oil. 50:1 is too lean. It lasted almost 50 years so far, there's no reason to blow it now.
     
  5. OkieBo

    OkieBo New Member

    Messages:
    199
    State:
    oklahoma
  6. Bubbakat

    Bubbakat New Member

    Messages:
    4,532
    State:
    McMinnvill
    That fuel mix for that motor is 24:1. As stated it has bronz bushings instead of bearings . The oil not only lubs the parts but also acts as a cushion between the bushings and the crank.
    You could proably get by with 32:1 but if it was mine I would use it at 24:1
     
  7. peewee williams

    peewee williams New Member

    Messages:
    3,111
    State:
    Pembroke,Georgia
    The old motors called for 30 weight non-detergent oil.Back then,this meant oil and oil alone.Does anyone know if there is a 30 weight oil of today with NO additives what so ever in it.Just pure (preferably paraffin base) Oil?Approx.25 years ago,a oil company Representative told me "I would not run a old 2 cycle engine of any type with a modern non detergent oil,as there are many additives beside detergent being added to todays oils.I would run a modern 2-cycle oil at the manufacturers recommended ratio".I had asked,and to the best of my memory,this was the exact answer.I had previously gotten (wishy washy) different opinions and answers from 2 OMC representatives.There still seemed to be a lot of controversy about the PROPER 2-cycle oils back then.(still is)peewee-williams
     
  8. Catmaster

    Catmaster New Member

    Messages:
    391
    State:
    SE Kansas
    That is a good question to ask. I was wondering the same thing. My uncle has that same year.
     
  9. OkieBo

    OkieBo New Member

    Messages:
    199
    State:
    oklahoma
    Well i finally water tested my motor since i put new gaskets in the fuel tank to gain back the pressure. I went with the 24:1 Mixture useing evinrude/johnson oil and it smoked a little bit upon startup but cleaned up on higher throttle! Even when it idled after warmup was little to no smoke! It ran like a champ and fired up with little effort! It was a good day with the old motor.
     
  10. OkieBo

    OkieBo New Member

    Messages:
    199
    State:
    oklahoma
    Well i think when i tested the motor last I still had enough thinner mix in the tank to keep a good running motor. I took my boat to the keystone gathering and put a full tank of 24:1 and it bogged down so hard i could barely troll along. After it was shut off oil would seep out of the exhaust like no tommorrow. I dumped all the mix and started with 50:1. Today i took it out on the water and the boat started fine i finally messed witht the slow and high speed knobs. Whooooaaaaaaaaaaaaahhhhhhhhhhhhhh nelly! This boat just tripled its speed! I did not think that an 18hp motor would push me and my gear that fast? I will try to find some nondetergent30 wt and mix up some 24:1 and see if there is a differance. It was kind of fun to find that more power, i had to cruise the lake even in 20mph winds. Motored on like it was meant to be there!
     
  11. fishhook

    fishhook New Member

    Messages:
    658
    State:
    Willow Woo
    I had a 1950 model Johnson 10hp with the oridginal green paint and came with a red metal tank, the label on the tank reads 16:1. As a matter of fact I still have the tank if anyones interested. The gears stripped in the lower unit so I sold the motor to a guy for parts because I could'nt find any gears to fix it with and it was to expensive to have them made but it sure ran good.
     
  12. peewee williams

    peewee williams New Member

    Messages:
    3,111
    State:
    Pembroke,Georgia
    5.12 ounces to the gallon or 30.72 ounces.to 6 gallons of gas is 25:1.Two pints or one quart is 32 ounces.Thats close enough.