Now that I have a set of good working, for now anyway, coils in my car and at least 2 good spares, I have a question. Should spare coils be swapped in and run from time to time, or will they be ok if stored in a safe place, like under the rear seat of my Touring? What's your opinion?
I for 1 haven't done this but your question gave me an idea of what I should do with the spare I carry. That would be to place a coil in a 1 gallon storage zip-lock bag with a bag of small desiccant.
Frankly, unless I were venturing WAY away from home, i wouldn't even bother carrying a spare, but that's just me. I've just never had a good rebuilt coil fail. Not to say it couldn't happen, but it doesn't happen as much as some people seem to think. I'm sure someone will post they had one fail and they will not leave home without a spare, or spares. That's fine too. Nothing wrong with carrying spares of things, and the further from home you venture, the more it makes sense. But when it comes to coils, my theory is that in the rare circumstance a good rebuilt coil were to fail, you could easily make it home on the other three, if you are just out for a drive.
If you do choose to carry spare coils, I'd recommend packaging them in a manner such that the points cannot get damaged by them sliding around under the seat or other things under the seat sliding around into them.
Spare rebuilt coils should be protected, any undue physical stress to the upper point hardware will change the electrical settings. Keeping them in a spare coil box with a cover is ideal.
You're right that a coil going bad is rare, happened once in 40 years for me. But I always carry a spare coil, not just for my T, but for another on tour who may have issues with a coil, so a spare is carried for care of those in need
Carry spare coil in wrapped package, the Coil Doctor (B. Mize) ships them this way, carefully packaged, good to keep the mechanicals OK in the tool box!
In my vast experience with questionable conclusions I have found that the bad coil you take out and store under the seat or in the toolbox will often cure itself. After a time when the next coil poops out it will work fine for some time. Yes it's strange but tell me if this hasn't happened to you. This phenomenon has gotten me home several times.
I use rice as a desiccant in the zip lock bag and a small bungee to hold my spare coil in a specific place so it doesn’t get damaged, but I also carry a "JUNK" coil to show spectators what one looks like!
Don't leave home without one (spare). I have good coils from one of the best rebuilders around, but one went bad while on tour. I could have continued because I only had a miss on 1 cylinder. Luckily, Charlie had a spare and I continued on without a hitch.
On the other hand, if you run a distributor, I'm told that 2 spare condensers are in order because they don't last long and if it goes bad you are "dead in the water".
Bill, if it was one of mine, I will send you another one. Unfortunately, with the age of windings, they can a will occasionally fail.
Please let me know.
The Coil Doctor