Dead coils

[BarryCogan]

I have a head scratcher. 1912 with Heinze coils.
On Thursday I drove the car in a FMC event in Detroit. Car ran well but seemed to hesitate on acceleration frequently.
Yesterday I decided to investigate. Turned crank and #1, #2, #4 coils had very strong buzz, #3 a bit weaker. Took coils out to check points and the lower contact point on #3 coil just fell off. Figured that was likely the cause of the problem. I knew I had a spare coil at home so I put 1, 2 and 4 back in the coil box.
Today I returned with the spare coil. Turned crank listening for buzz and only the "New" coil buzzed. Took all coils out again, cleaned contacts on coils, bent and cleaned contacts in coil box, replaced coils, turned crank, same result. Took coils out again and moved working coil around and it buzzed in every position in coil box. Individually put other coils in different positions, none ever buzzed.
Took a set of coils from another car to test. All four work as normal. Car starts and drives fine. I am quite certain now that I have 3 bad coils, but why. They worked fine Saturday afternoon but less than 24 hours later, nothing. Switch was off and battery disconnected.
Thoughts?
Thanks, Barry

[kmatt2]

Actually you have four bad coils, the four that you were driving on when you last drove the car, and noticed the poor acceleration. You don’t say if those coils have been rebuilt to your knowledge, but I would say that if you are lucky, the poor acceleration was a sign that the condensers were starting to fail. That would be way better than if the coil winding’s were failing, because the bad condensers can be replaced.

[Jerry VanOoteghem]

Actually you have four bad coils, the four that you were driving on when you last drove the car, and noticed the poor acceleration. You don’t say if those coils have been rebuilt to your knowledge, but I would say that if you are lucky, the poor acceleration was a sign that the condensers were starting to fail. That would be way better than if the coil winding’s were failing, because the bad condensers can be replaced.

Yes, but even with bad condensers his coils should still buzz.

[Adam]

Yes, but even with bad condensers his coils should still buzz.

Only until the points don’t make a good electrical connection anymore…