I was trying to ease into this topic, but that may not have been the best approach…
If the original coil is still in place, and just has a bad secondary, there is an alternative to the battery system. If you have a coil with a bad secondary and you try to start it, you’re still generating current in the coil primary circuit. You can use that current to fire another coil mounted externally. Detach the wire that normally goes from the coil to the points, and add on some wire to extend it out from under the mag plate. Attach it to the primary lead on an OMC Universal coil, and mount the coil on the block of the motor with the OMC coil ground wire grounded to the block. Then run a spark plug wire from the OMC coil to the spark plug. This may work better if you remove the bad secondary from the bad coil, I can’t remember whether I did that.
Tom
Now this is a really clever idea. Even if one had to get some magnet wire and wind a new primary it’s good. It might be made to work with various other coils.
Back about 1975-1985 I used to replace the oem coils with Kmart universal coils and mounted the caps on the coil bracket on many snowmobiles before cdi came out. I used caps from a 1969 chevy impala. Worked great.
I tried using an external coil connected to the old coil in the magneto. It didn’t work out. I think if there were enough turns left on the secondary side this may work out better. There would enough voltage to kick back to the primary side of the coil to fire the external coil. One of these days I would like to try this out again to see if this would work.
Just had a thought – wonder if the COP (coil on plug) that Ford uses would work on an OBM? They are relatively cheap, like 8 for $30 on the bay. Hmmmmm,,, JW
Just had a thought – wonder if the COP (coil on plug) that Ford uses would work on an OBM? They are relatively cheap, like 8 for $30 on the bay. Hmmmmm,,, JW
I wondered about this too. But most COP coils seem to be long to reach down into the plug wells, and most outboard plugs are pretty close to the motor cover. What about "coil near plug" coils?
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