I don't have the books handy today but earlier in the week I was looking for info on another ignition related issue. In several of my old books they explained the system you're asking about and how to service it.
Do you have an old Motors Repair manual, or any other old automotive books that tend to cover more than just one manufacturer?
If you can't turn up anything I can try to search again.

Grigg

•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
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"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-