OK now I feel dumb. I thought mechanical was with the advanced hooked up.
OK initial is with the advanced unhooked, carb plugged at idle. Yes, With the "Vacuum" adv unhooked. you have a vac and a mechanical adv
What is mechanical? Counter weights and spring, in the dist. that advance the timing with rpm.
What is curve? How many degrees the weight and springs give you.
Vacuum advance is obviously with it hooked up and nothing more should be done.