Tiny;
"Octane Selecter"?? Where/what is that?
I don't know when Chevy stopped using it. It allows the timing to be advanced or retarded up to 10 deg each way to adjust for the wide swing of gas quality (octane) back then.
Octane selector on my '38. How to use it. You can see gas back then had much lower octane than today. You can advance your timing a lot over the manual recommendation and not have pre-ignition. That's why I time by ear, the spec in the manual really doesn't apply with today's fuel.
