1920s HT coils: A century of longevity?

[markpb]

May I consult  the collective wisdom please on the serviceability (or lack of it) of 1920's HT coils?

 

 The issue is this: I have a modern (about 1950s) coil (works perfectly) in my mid 20's car, but wish to replace it for a proper period item - but only if I think there is a sporting chance that such an item could  work... no guarantees at auto jumbles of course..

I have quite a bit of past experience with magnetos- these invariably have to be rebuilt within 100 years (shellac disease often), but I do not know if early HT coils are capable of lasting -perhaps their insulation is rather more long-lasting.  Any opinions gratefully received. 

[Bloo]

I say go for it. Throw the 1950s one in the toolbox (or trunk if you have one). I have a 1913 car with a Splitdorf magneto, reputed to be troublesome, still working fine. I have a 1936 car with a hole in the coil. It should be full of oil I think, but isn't. It works fine.

 

Of course you have a right to be concerned, and the insulation on the magnet wire back then was inferior compared to what is available now. I am looking for a spare for that 1936 coil too. I don't trust it due to the missing (probably) oil.

 

If you can carry a known working substitute, why not?

 

There is a thread right now over in the Prewar Buick Technical section about teens-twenties Buick "mailbox" coils, and how to test them. I'll bet they find some that still work.

 

[markpb]

Thanks very much for that. Sounds then like a real chance...

[26-25Buick]

Mark, it would depend a lot on their history as the early coils were air cooled rather than sitting in an oil bath. As you know this allowed corrosion and moisture in and caused them to short out or the windings to breakdown. Having said that I’m running the original coil in my 26 Buick without a problem and have a couple of 1912 Cadillac coils that test perfectly, in terms of resistance so I expect them to work, once I get the car restored. So the good ones are out there and I’d follow Bloo’s advise and swap back to original. 
To be honest I’ve had far more trouble with condensers than coils.

[markpb]

Thanks for that too. I will defo try one (or two..)      ( BTW I so agree with you on condensers ...)