I think you may be doing it wrong. I am presuming here, that you are using a 1 bbl. with the vacuum advance line below the throttle blade (stock Rochester for example, also Carter YF.) Set your idle to factory specifications. its pretty low like 400-450 maybe 500-550. Set the timing bb to the pointer. That is it. TDC.
The distributor is either going to have 12 degrees or 14 degrees of mechanical distributor advance. But the motor sees double that.
So 1750 distributor rpm is 3500 engine rpm, 12-14 distributor advance is 24-28 at the motor. The mechanical advance will come in gradually (as the rpm increases, the centrifugal force flings the advance weights- which are under the point plate- outward a measured amount until they are fully out no later than 3500 rpm, unless the mechanical advance mechanism is broken, rusted solid, or just so gummed up that the advance weights cant move.
So assuming the advance weights are moving, you have 24 to 28 degrees of mechanical advance.
Now, sometimes, the factory setting of tdc is conservative or you are in an area in which the motor can use a little more advance. This is where initial advance comes into play. Use the dial back light. Dial in 5 degrees advance. Point the light at the flywheel window, loosen the screw, move the distributor counter clockwise until the bb lines back up. Now, the motor starts at idle with 5 degrees of initial advance. The mechanical comes in gradually, and in this scenario, at 3500 rpm, you have 29 to 33 degrees of total advance (24 + 5 or 28+ 5 depending on the distributor.
