It sometimes takes me a while - Deadhead, are you wanting to put a modified curve in your new distributor? And its a Cardone with points? And it has slots on the bottom of the upper rotor shaft like the one in the photo, except it uses a point cam?
The one on the bottom row of the photo is still lying on my work bench - it is stamped "13L" at one slot and "18L" at the other. These are distributor degrees - and are doubled in the engine. The 13L will net 26° at full travel and the 18L will result in 36°. The springs determine when the flyweights will push the rotor to full travel. The factory springs are usually pretty stiff and take lots of rev's to get up to full advance. This is a chart from a late 70's Ford ignition training manual - it shows a typical passenger car advance system.
The mechanical advance data shows that the full advance won't be in there until the engine is turning fast enough to get the distributor up to 2000 or more rpm - this is well over 4000 rpm at the crank. On a stocker, the initial advance (that you set with a timing light) will be like 3°-5°. Combined - you would get a max advance of about 30°-31° with her wound right out.
To get good performance you want this total number to be 36°-38° and you want it at 2800 to 3000 rpm. You also want some additional initial timing in the engine right away to build low end torque. So you work backwards from the maximum. Put in 10°or 12° intial, and select a slot good for 26° divided by 2 = 13°. Together they will net 36°-38°. For reference, the 13° slot in my sample is .480 inches (15/32).
If you leave the factory (stiff) springs in there they will take forever to get up to full advance. You want this to come in more quickly so lighter springs are required. Mr. Gasket has a Ford spring set #925D that has something close to what you want.
Hopefully you got more information this time around! Good Luck!
Steve Metzger Tucson, Arizona