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  1. #1

    Question 1968 OMC 120 stern drive high idle on start help please!

    Hello everyone, I have a 1968 arrow glass 120 stern drive with the CUE-16c engine 153 ci dual 2bbl carbs. The problem is it seems like its idling fast at warm up and doesn't taper but just keeps getting higher and higher rpm then I get nervous and shut it down for fear of over doing it. What is the proper idle idle speed on warm up for these old engines with choke disengaged and should I prime the carbs with the main throttle before start up. Thank you for your time!

  2. #2
    Join Date
    Dec 2006
    Location
    Chaumont Bay, N.y., USA
    Posts
    6,015

    Default Re: 1968 OMC 120 stern drive high idle on start help please!

    Ayuh,.... Idle should be 600/ 750 rpms,.....

    'n ya prime the throttle at least once to Wot, to set the auto-choke,.....
    Any Grease is Better,... Than No grease at All....

  3. #3

    Default Re: 1968 OMC 120 stern drive high idle on start help please!

    Thank you, I will see if I can get within those marks I appreciate your response!

  4. #4
    Join Date
    Jan 2017
    Location
    Salem Oregon
    Posts
    174

    Default Re: 1968 OMC 120 stern drive high idle on start help please!

    the carbs may need to be tuned to each other... the slightest bit of mis adjustment can cause your issue... also check to see if the throttle control cable is dragging or otherwise mis-adjusted.

    almost always when a cold engine is started, it will labor a bit to run, and so needs a richer mixture/more fuel to run... as the engine warms, the intake air warms a little and the oil gets thinner, it will run much easier.... if the throttle plates are open slightly too much and cant be closed any further, the rpm will climb as the engine warms and runs easier...

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