1) From 52Carl in 2016:
"The octane selector was originally for fine tuning the timing on the fly between gas fill-ups from different suppliers which had differing octane ratings. You could advance or retard the timing with the octane selector without a timing light or vacuum gauge and never lose your place as to where the needle is on the ball (zero on the octane selector). This is no longer needed as octane standards are more strict in modern fuels from one gas station to another.
I personally, would rather have a manual lever to adjust the timing while driving, similar to what came on Model Ts. But I am weird, I have been told.
Carl"
1a) Set it to zero and leave it there.
2) Yes, that is correct. If you have a ball, that is what you set the pointer on. Just check it first, it's probably OK. If not, rotate dizzy till it is, but remember where it was in case it runs better where it is at....or where at it is, or at what place it was at. At that point, it is what it is.
