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Results 1 to 4 of 4
  1. #1
    Join Date
    Apr 2010
    Location
    Florida
    Posts
    18

    Default 1958 Johnson 18hp RD-12 2cycle Mixture..?

    Can anyone "safely" give me the Fuel oil Mixture for this motor? I'm trying to use TWC3. The last time this motor ran (18 yrs ago) I think they had to use crude ?
    Anyway after rebuilding the ignition, water pump, carb, foot seals, reed and intake gaskets, I converted from a pressure system to pulse vacuum single line tank! (waiting on tanks to be delivered) If I missed something please feel free to pass on some info.

    Oh ya, Idle and run Mixture start points would be a blessing...

    Thanks all!

  2. #2
    Join Date
    Jul 2007
    Location
    florissant, missouri, us
    Posts
    224

    Default Re: 1958 Johnson 18hp RD-12 2cycle Mixture..?

    its in some of the older posts ive got a 56 evinrude 7.5 and its 1 quart per 6gals but joereeves knows

  3. #3
    Join Date
    Feb 2001
    Location
    Central West Florida
    Posts
    11,742

    Default Re: 1958 Johnson 18hp RD-12 2cycle Mixture..?

    The 1958 18hp Evinrude ot Johnson incorporates needle, roller, or ball bearings on all of its powerhead components (main brgs, connecting rod, wrist pin, etc), and s such you can safely use the 50/1 mixture (1 pint of 50/1 TCW-III oil to 6 gallons of gasoline). A octane rating of 87 will be fine.

    (Carburetor Adjustments - Two Adjustable N/Vs)
    (J. Reeves)

    Initial settings are: Bottom high speed = seat gently, then open 1 turn out. Top slow speed = seat gently, then open 1-1/2 turns.

    Setting the high and low needle valves properly:

    NOTE: For engines that DO NOT have a shift selection, obviously there is no NEUTRAL position. Simply lower the rpms to the lowest setting to obtain the low speed needle valve adjustment.
    (High Speed) Start engine (it will run pretty rough), shift into forward gear, take up to full throttle. In segments of 1/8 turn, waiting for the engine to respond between turns, start turning in the bottom high speed needle valve. You'll reach a point whereas the engine will either start to die out or spit back (sounds like a mild backfire). At that point, back out the needle valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest setting.

    (Low Speed) Slow the engine down to where it just stays running. Shift into neutral. Again in segments of 1/8 turns, start to turn the top needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running. Eventually you'll hit the point where the engine wants to die out or it will spit back. Again, at that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.
    When you have finished the above adjustments, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.

    Thousands of parts in my remaining stock. Not able to list them all. Let me know what you need and I'll look it up for you. Visit my eBay store at:

    http://stores.ebay.com/Evinrude-John...tc?refid=store

  4. #4
    Join Date
    Apr 2010
    Location
    Florida
    Posts
    18

    Default Re: 1958 Johnson 18hp RD-12 2cycle Mixture..?

    Quote Originally Posted by irishwoodsman View Post
    its in some of the older posts ive got a 56 evinrude 7.5 and its 1 quart per 6gals but joereeves knows
    Irishwood, Thanks for the info, Joe did Verify that ratio. Keep up the "great Info"

    Thank you!
    customan

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