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Thunderbolt V

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  • Thunderbolt V

    Learned a few things about Mercruiser ignitions last week. We had a trip planned to leave town a week ago Thursday, we had to wait while a replacement puller arrived. In any case we arrived Valdez about 4 Pm, loaded up and finally cleared the harbor about 8... in the fog... We were just about on step when the motor stared running like crap. spittin and sputtering and no power. I got off to the side and dropped the hook, fired up the Honda to make sure we could move if we had too. I messed around for a good hour, checking fuel and plugs. had spark on all 8, but it was erratic and the big indicator it was ignition was the tach was not functioning correctly.
    I was pretty sure it was a ignition issue, we aimlessly motored back to the Harbor and spent the night. Did a compression check the next day and after speaking to Marine services in Homer decided it was the senor in the distributor. They got a new one on its way to Valdez and by 7 the next day we were back in action.
    See pic of new and old sensor, definitely needed to be replaced.
    Attached Files
    1982 2580 "HI-BOY " IN 2 DEEP 5.7LX ALPHA

  • #2
    Anybody ever try tweaking their base timing on these Tbolt ignitions?
    1982 2580 "HI-BOY " IN 2 DEEP 5.7LX ALPHA


    • #3
      Have never played with the Tbolt ignitions but have had the same experience as you did ONCE. I now carry a complete spare distributor with both drive gears for standard and reverse rotation engines and a spare module too. Nothing sucks as much as a module failure.
      "Joint Venture" 1978 28' twin 2017 Vortec roller cam 383/6.3L 350hp engines - You name it, I've either replaced it, restored it, rebuilt it or repaired it. That's my job now that I'm retired.