Set the base timing, then increase the rpms while watching the timing mark move. Once it stops advancing, turn the knob until the mark is back where you set it. The number on the dial is how much advance you have. Once you know how far it advances you can better decide where your base timing should be set to arrive at the total you want. If you're willing to tear the distributor apart you can change the amount of centrifugal advance. Pull the reluctor off the shaft- keep track of the roll pin that keeps it from spinning- unscrew the stator and lift it out, remove the vacuum advance unit and the 2 screws retaining the base plate and lift it out. You'll see the weights and the arms on both the upper and lower distributor shafts, notice the 2 different openings in the arms, the longer opening will give you more centrifugal advance if you need it. To realign it you'll need to remove the inner snap ring so you can slide the upper shaft up enough to rotate it about 1/2 turn, drop it back down aligned with the longer slot, and reassemble the whole thing. Recheck the advance as before. You'll want to note the rpm where the advance is all in, I like to see 2800-3000 as a ballpark.