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  1. #1

    Default Gray 109 6th cylinder problems

    We have a 1958 Lyman that we restored about three years ago. The engine runs ok but the 6th cylinder always fouls out. When we restored the boat we did do a little work on the engine and we did re-seat all the valves with lapping compound. We have tried different spark plugs, checked compression, and got a new spark wire. Does anyone know what the correct gap is supposed to be between the valve and the rocker? Could we have that set wrong and we are getting blow by causing the plug to foul? We have been struggling for two years to get this thing running decently if anyone has experience with these things and would share it that would be great. Thanks

  2. #2
    Join Date
    Feb 2010
    Location
    McHenry, Illinois, USA
    Posts
    71

    Default Re: Gray 109 6th cylinder problems

    The Gray 109 valve clearance is .017" on both intake and exhaust

  3. #3

    Default Re: Gray 109 6th cylinder problems

    Do a compression test to find out if the valves actually seal that cylinder. Auto Zone has "free" compression testers.

  4. #4

    Default Re: Gray 109 6th cylinder problems

    Ciao anche io ho un motore gray Marine modello 109RD 6 cilindri a benzina , sto cercando tutti i dati di questo motore ,, CILINDRATA , CAVALLI FISCALI , HP , PESO DEL MOTORE , CONSUMI ORARI , POTETE AIUTARMI , MAGARI POTETE PREDERE QUESTI DATI DAL VOSTRO LIBRETTO MOTORE . grazie mille Roberto

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