Set the octane selector at 0 and leave it there. The scale is not all that accurate to start. It was used to change the timing on the side of the road to compensate for a bad load of gas or changing atmospheric and altitude condition. Get it set for tdc. Then get a used analog dial back timing light, dial in whatever advance you want to try. For a stock motor, 3-7 degrees with today’s fuel is pretty common.
