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  1. M

    3.0 litre OMC tune up specs

    I have seen several differant specs for the point gap and timing and dwell. I also see Mercrusier and OMC are not the same spec. Is there anyone who has the CORRECT specs? I am running mine presently at 18 gap and 6 degree advance. Its ok but max RPM is about 4400. Thanks
  2. M

    OMC 3.0 Running rough

    I have 87 OMC 140 with a Rochester 2 GC. The carb was rebuilt as well as the motor by a very good shop. I am having issues with the motor idle being very rough at times and hesitation as you increase RPM. I am also seeing the plugs are getting black fouled. The motor starts up on...
  3. M

    OMC Cobra 140 Manifold Question

    I have been experiancing operating issues with a 87 OMC 140 that has been completely rebuild by a reputable shop. I am leaning to a cracked intake/exhaust manifold. I am looking for the proceedure to check if it is. --------------------------------------------------------------------------------...
  4. M

    88 OMC 140 Stops Running

    I have an 88 OMC 140 in an 88 Bayliner. The motor was completely rebuilt and reinstalled. I replaced the water pump, fuel pump as well. I can run the boat for 1 hour and it runs great, at about 1 hr it starts to miss and it lead to a stall and no run situation. After some time it will restart...
  5. M

    Ignition Timing 3.0 OMC

    Does anyone have the correct ignition timing spec and idle speed for a 1988 OMC 140/ 3.0 motor? Thanks
  6. M

    OMC Cobra to Mercruiser Conversion

    I have a 1988 OMC Cobra 3.0 motor that has serious cracks and has effected the running so that it has to be removed. I have located a 4.3 Mercruiser motor and drive that is in nice shape. I am wondering what I might do to make this swap work. Could the OMC drive and bellhousing be used with the...
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