1955 5.5 Johnson fuel mix?

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    jimk

    Replies: 18
    Topics: 9
    #176954

    I have a 1955 5.5 that i brought back to life with new points,condenser,coils,waterpump,carb kit ect. My question is what mix to use. I think its supposed to be 16:1 and was told I could run at 24:1 with newer oils like the Johnson tcw lll. Now I would like to keep it running for many more years so opinions are welcome from the pros here. I ran it today with a mix of 20:1 and it runs great on my little 12 ft boat but not sure whats best. Thanks for any advice! Jim

    Avatar
    amuller
    US Member - 2 Years
    Replies: 872
    Topics: 138
    #176958

    I use 24-1 in mine.

    • This reply was modified 3 months, 1 week ago by Avatar amuller.
    bobw
    bobw
    US Member - 1 Year
    Replies: 601
    Topics: 28
    #176959

    I run 16-1 in my ’54 5.5 per the original factory recommendation. Modern TCW oils burn a lot cleaner and probably do offer a higher degree of protection but I figure oil is cheap in the overall scheme of this hobby.

    Bob

    1954 Johnson CD-11
    1956 Johnson RD-18
    1958 Johnson QD-19
    1959 Johnson QD-20

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    jimk

    Replies: 18
    Topics: 9
    #176960

    At 16:1 do you have any plug fouling? I am not worried about the cost for just a bit more oil but would like to avoid changing plugs out in the middle of the lake. If all is ok I wouldn’t mind using the factory recommended amount. I also use premium gas as thats all I can get without ethinal in it.

    bobw
    bobw
    US Member - 1 Year
    Replies: 601
    Topics: 28
    #176963

    No plug fouling at 16-1 with modern TCW oil.

    Bob

    1954 Johnson CD-11
    1956 Johnson RD-18
    1958 Johnson QD-19
    1959 Johnson QD-20

    Avatar
    garry-in-tampa
    Lifetime Member
    Replies: 3143
    Topics: 30
    #176982

    Why is my post disappearing when I hit the [submit] button ? ? ?

    Attachments:
    Mumbles
    Mumbles
    Canada Member - 2 Years
    Replies: 4183
    Topics: 424
    #176985

    Sticking with the factory recommended 16:1 will help you sleep easy tonight. The reason the 5.5 and 7.5 OMC motors of this era need the rich mix is because they don’t have any needle, ball, or roller bearings in them, only sleeve type friction bearings which need the extra lube. Running them at high speed with a leaner gas/oil mix runs the risk of starving the bearings for lube and that in turn makes the crankcase too small for the connecting rods as they can seize on the crank and then break through the side of the block leaving you stranded without a paddle.

    As stated, this topic can go on forever but when you think about it, these motors have probably lasted this long because of the amount of oil they drink. If the motor is well tuned and has decent compression, they will hardly smoke at all using modern TCW III oil. Smoke from any two stroke motor is usually more noticeable on startup, when the motor is cold, but goes away as it warms up.

    Attachments:
    Mumbles
    Mumbles
    Canada Member - 2 Years
    Replies: 4183
    Topics: 424
    #176989

    Why is my post disappearing when I hit the [submit] button ? ? ?

    I don’t know why but mine was doing the same thing the other day over in Dockside. It finally posted by opening a duplicate window and backing up to copy/paste the original text before the gremlins found it again. Later on I found the missing posts marked as ‘hidden’. Never did figure that one out.

    bobw
    bobw
    US Member - 1 Year
    Replies: 601
    Topics: 28
    #176990

    Very well stated by Mumbles. This series of motors was prone to throwing a rod through the block without adequate lube oil. As he stated, even at the 16-1 ratio they will smoke very little once properly tuned and the carb is dialed in correctly.

    Bob

    1954 Johnson CD-11
    1956 Johnson RD-18
    1958 Johnson QD-19
    1959 Johnson QD-20

    Tubs
    Tubs
    US Member - 1 Year
    Replies: 2355
    Topics: 141
    #176992

    Search “poof”. You’ll find that its not that uncommon.

    Why is my post disappearing when I hit the [submit] button ? ? ?

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    JOHN HOLBIK
    Canada Member - 2 Years
    Replies: 7
    Topics: 0
    #177000

    My father ran a fishing resort here in Northwestern Ontario Canada from 1947 to 1995 ,We had at least six 5,5hp Johnsons great motors except for the lack of a shifter lock which caused users to creep shift them.We mixed all our gas at 25to1 and never had a thrown rod this was with the old oils of many different brands mostly automobile oil and the oil was never mixed the same twice in a row lots of guess work by us kids,I still have the Cd12 my dad bought Brand new in 55 it has thousands of hours on it still runs well.
    I believe the reason they threw rods was there was no neutral stop position for starting people would turn the grip it would advance to full and the motor would start and over rev and I saw alot of people sit there with a dazed look on their face as you screamed slow it down or they would semi panic and shift into gear and you could almost hear the ears on the clutch dog being sheared off/
    John

    lindy46
    lindy46

    Replies: 286
    Topics: 21
    #177011

    Personally, I use 16:1 in all my 50’s small motors.

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    jimk

    Replies: 18
    Topics: 9
    #177097

    I took it out today on my little Lund and put about 4 hours on it. I used the mix of 20:1 I had and it ran great. Trolling most of the time and no plug fouling so will go to the 16:1 next fill on the tank. I opened it up a couple of times just to clean it out and all in all I am very happy with the motor. Also managed to catch a limit of walleye!

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    outbdnut2
    US Member - 2 Years
    Replies: 1138
    Topics: 57
    #177142

    Why is my post disappearing when I hit the [submit] button ? ? ?

    I don’t know why but mine was doing the same thing the other day over in Dockside. It finally posted by opening a duplicate window and backing up to copy/paste the original text before the gremlins found it again. Later on I found the missing posts marked as ‘hidden’. Never did figure that one out.

    This has been happening randomly to me – happened again yesterday when I tried to start a new subject over in Dockside.
    Dave

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    fleetwin
    US Member - 2 Years
    Replies: 2713
    Topics: 33
    #177143

    I would definitely stick with the original 16:1 recommendation, especially for the reasons mumbles stated….While it is true that oils have improved over the years, I wouldn’t risk it….The beauty of these engines is that when properly tuned, they barely smoke at all at 16:1, these engines don’t foul plugs either.

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