Black Carbon on Ignition Coil

[Rkymtn57]

1956 Johnson 10hp.  QD-17

After rebuild and running fine , now i have lost spark and have found black carbon on the coil faces.

One more than the other  i have checked all wiring & connections and everything looks fine.

Points are still set correctly.  Would anyone have any idea what is causing this ?

Are the new coils  ruined ?   Thank you.

[Steve Martin]

Are you talking about the laminate face in the center of the coil?  If so, your coils are out too far and are dragging on the flywheel.

[crosbyman]

post pictures.   no carbon should be reaching that area  under the FW

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[Rkymtn57]

Yes        Ok , I thought they were set back just right but maybe not , ill try again.

Still no spark , I have no idea why i have such a problem getting spark.

I had it running fine at one time but now once again no spark.

All mag plate parts are new.

[Rkymtn57]

Also , the replacement coils just have so much movement in the screws , i can only move them back so far and no further.

[crosbyman]

coils must line up with the  base   fingernail must not snag going up or down .

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[seakaye12]

For a while….and it was a few years back….there was a batch of aftermarket coils that had bad laminates.  The laminates were off-spec just enough to cause them to be very difficult or impossible to set the air gap correctly.

A fair amount of grinding/sanding/cussing could remedy the issue sometimes.

I bought some Sierra branded coils during that period that had that issue.

What brand are your coils?  If they were sourced on Amazon or e-bay….I would consider getting OEM branded  (OMC/BRP) coils.

 

[aquasonic]

By testing the coils with an ohmmeter from the top wire on the coil to the steel contact in the sparkplug boot, you can at least establish that there is continuity from coil to sparkplug. If there is a bad connection in the wiring, and the coil is generating power from the flywheel magnets, then the charge will try to get to ground any way it can. This results in damage to the coil.

Another common problem with coil replacements is that either the upper or lower fine coil wires are not tucked in enough toward the coil. The spinning flywheel hub makes contact with the fine wire, rubs off the insulation in no time, and causes a short.

Condenser wires need to be bent downward to prevent contact with the flywheel hub.

If you can post a few pictures, there may be a visible problem that someone might notice.

[fleetwin]

There may be a leak in the coil case causing arcing to the mag plate/flywheel which will leave a black residue.  Usually you will see a tiny pin hole where the secondary circuit is arcing to ground.   Perhaps the plug wire is not connected correctly or is split somewhere causing the coil secondary to seek out its own ground.

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