Since the subject of distributors and correct operation, i.e., the advance curve keeps coming up ... here are some pertinent pages from the '72-'73 spec book ...
Page 47 gives the crank pulley and settings ... note that the third notch at 30 degrees Before TDC is not labeled in the drawing!
Next, p. 46 gives the instructions for checking/setting the timing:
Finally, p. 48 gives the checking points in tabular form that corresponds to the advance curve posted above from the service maual:
Please note that above idle the vaccum retard diaphragm has no effect on the advance curve, so having it disconnected has no effect on engine drivability or responsiveness!!! It is used only to improve emmissions compliance at IDLE!
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Warren Hall
1973 911S Targa