Mercury 9.8 Thunderbolt ignition to phelon mag conversion

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  • May 18, 2015 at 2:01 pm #1528
    jake11
    Participant

      Good morning, folks. I have 2 old mercs in the garage. 1 is a 71 with the phase maker ignition. The motor is in beautiful shape has great compression and the LU is super solid. The other is a 69 with phelon mag ignition and is missing the LU. Compression is decent. I think the two cylinders are within 3 or 4 psi of one another.
      The motor with the PM ignition is repeatedly popping one of the ignition coils(3 now) and at 50 to 100 a piece its getting old fast. I’m assuming something is going on with the extremely expensive and hard to find stator so I want to swap over to the more reliable and easier to trouble shoot phelon mag system. Some of the parts from the 69 are missing but the majority of it is there and the parts and nuts and bolts needed are cheap. So! Anyone ever done one of these conversions that could give me a run down? I have too many hours, dollars, blood, sweat and tears wrapped up in this motor to give up on it so any help would be greatly appreciated.

      May 18, 2015 at 6:13 pm #16360
      jasonh
      Participant

        I converted a mint condition 1970 9.8 back to points and condenser for same reasons. Its one of my favorites now. For conversion to older ignition, you need top bearing carrier from 64-69 powerhead. Throttle linkage for 69 should bolt up to 69 mag plate assuming the little perch is bolted to mag plate. You use ignition points cam, mag, flywheel, and bearing carrier from 69. That should be it.

        Mercs are shimmed for crank endplay, like .008-.011. You probably want to use the shims you find in powerhead you are using and make sure you have proper endplay. If I remember correctly, the shims are between bearing carrier and block.

        May 18, 2015 at 9:20 pm #16375
        jake11
        Participant

          OK. Sounds like this is over my head lol thanks for the info though! I have a buddy that’s a mechanic by trade maybe I’ll have him give it a look over and the description provided and see if he can make heads or tales of it. If not I guess I’ll just toss this thing. No way I’m paying 300 for a stator and 100 a piece for two new coils for a motor I got for 75 bucks.

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