Alvin -
If I understand Cletis' comment, you use the starter because it creates a flat spot front to back on the bottom of the engine at which to tell how much rise from back to front or fall from front to back the engine has on it as it sits in it's spot in the vehicle. The difference in that angle created by the rise or fall compared to a level surface is the angle the pinion needs to sit at.
I think that's right!
Joe
