Ryan, what Gordon said.
It might be time to invest in a timing light. The cheapest start at around $35 and you probably don't need to spend much more than that for our purposes.
In our fragile air-cooled engines, timing is something you should be checking periodically. Even if the engine sounds like it's running fine, if the maximum advance is much over 30 degrees, the heads can overheat and toast things up in an expensive sort of way.
The distributor gradually increases spark advance from whatever it is at idle up to some maximum amount - usually by the time revs climb to about 2500. That maximum value is what you need to keep track of - much more important than the value at idle.
Sorry if I'm repeating some of what Gordon said, but it's a point worth repeating.
And once you're heavily invested in a timing light, it will help you track other things, too, like whether your distributor is delivering consistent spark up and down the rev range - an all-too-common source of 'rough running' in our cars.
Timing lights are also cool if you throw blacklight parties in your garage. Google '1970s' to read more about this.