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  1. #1
    Cadet
    Join Date
    Jan 2012
    Posts
    17

    Default Johnson QD-18 throttle

    Well, after much soul searching and deliberation, I bought a '57 Johnson QD-18 for my 12' Feathercraft Skippy rowboat. Thanks or those that replied with their opinions on size choice (5, 7 1/2,10, 18 HP). The guy had an Evinrude 18 that I really wanted, that he had run lots last summer, but the difference in weight made up my mind. He claimed this one was started but he decided to use the 18 as this one was a little small for his boat.
    Well the obvious tasks are at hand. Ignition, carb, impeller. Noticed something with the throttle linkage.
    When I rotate the twist grip from the idle stop, I can see the pinion gear and shaft rotating, but it seems to rotate through about 1/4 to 1/3 of its travel before the shaft leading to the throttle moves. Is that normal? Does the timing cam beneath the flywheel rotate before the throttle moves, accelerating the engine by advancing the timing before the carb comes off idle? Nothing seems broken or missing, and my Seloc manual doesn't really address the linkage. Just wonderin'. Not running yet...still have the impeller and fuel tank cleaning/hoses to go. The tank was holding pressure when I opened the cap. Might get lucky. Played with motors in my younger days but never really paid attention to the mechanical details...Dad did that.

  2. #2
    Supreme Mariner
    Join Date
    Jul 2006
    Location
    Florida Gulf Coast
    Posts
    19,310

    Default Re: Johnson QD-18 throttle

    Yes. IDLE speed is controlled by timing retard. As you speed up from slow idle, timing advances a bit before starting to open the carburetor, then they both operate in a synchronized fashion till both are at wide-open throttle position. The synchronization procedure should be in your manual somewhere. It is a pretty basic procedure.

  3. #3
    Cadet
    Join Date
    Jan 2012
    Posts
    17

    Default Re: Johnson QD-18 throttle

    F_R,

    Thanks for the reply. Yes, read about timing synch procedure, somehow missed the whole timing advance-retard process. Makes sense. Need to finish the process and get it in a barrel. Thanks again!

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