Pretty simple on mine. I start it & let it warm up then loosen the clamp on the distributor & adjust to the best (fastest/smoothest) idle with the octane selector set on 0. Lock the clamp then reset the idle if necessary & drive it. If by chance it pings under load I can fine tune using the octane selector to retard until the ping stops.
Info Chevy put out in '36 (I think) about using the octane selector. You can see from that, that these vehicles were timed to much lower octane than today's fuels.
