Robert, Thanks for sharing that. Do the instructions say or show the degrees on a graph? Also, if you have any of the springs, could you take a picture?

One way to save some time on the engine or distributor machine is to measure up the springs. It's a little tedious but so is installing different combos in the distributor.
Spring Rate can be calculated from the following:
> Number of coils; More will reduce spring rate
> Wire Diameter: Larger will increase spring rate
> Coil Diameter (O.D. - wire diameter): Larger will reduce spring rate.

Initial force will vary with length inside the loops, so measure that too.

For calculating spring rate for a coil spring, make a couple of assumptions.
1. Active Coils are 1/2 coil less because the last where it turns out doesn't spring.
2. Elasticity for the material. I've been using 11,000,000 lbs/sq in.

Spring Rate = (11,000,000 x Wire dia)/(8 x Active Coils x Dia^3)

This where the roughly 8 #/in rate for a primary spring cames from. But this is just based on the ones I've measured. Will vary with application.
The P2932675 super light springs work out to 0.68 lb/in each
The DC/MP Aluinum Electronic Tach Drive primary spring 1.3 lb/in