If you have 20* initial you're going to want to limit your mechanical to around 15-16. Your total number will be higher with the vacuum hooked up under light throttle. Wide open throttle it goes away.
OK maybe we are doing it wrong. Here is how we are setting it. Start the car and let idle with the advanced unhooked and the carb plugged. Turn the distributor until it smooths out and runs good. Which was about 20*. Hooked the advanced up and checked with the timing light. That is where we see the 60*.
So once we hook up the advanced do we readjust the distributor to 15-16*?