RPM_Speed

360 and 401 timing is the same. 1974 TSM (last year of 401 in cars) says initial range is 4-6 degrees BTDC (set at 5) @ 700 rpm or less with vac advance disconnected. Curb idle (auto in park, manual in neutral) should be 650-750 for auto, 700-800 manual. Total advance @2000 rpm (TCS wires disconnected at solenoid) should be 26.5-35.5 auto, 28.5-37 manual. It gives the centrifugal advance in steps, should be 19.5-23.5 @ 3000 rpm.

Total is kind of a big range, I would think, but I don't mess with distributors much at all, not as far as changing the curve anyway. I have changed springs in one or two before. Just guessing, had no real idea what I was doing, but the lighter springs helped performance a bit (GM dizzy) by seat-of-the-pants anyway.

Checked the 71 specs (9.5:1 compression) just for the heck of it.
Initial timing is 2.5 degrees BTDC @ 500 rpm with vac advance disconnected. Curb idle (auto in park, manual in neutral) should be 650 for auto, 750 manual. Total advance @2000 rpm should be 30.5-37.5, no difference between manual and auto. It gives the centrifugal advance in steps, should be 22-26 @ 3000 rpm.