Here is the card that I got from the Tech line guys. As everyone has said and the new paperwork details the duration at .050 is actually 271. This just gives you the opening and closing points.
312° Mechanical: P4120663
Duration Intake Nominal 312° Duration Exhaust Nominal 312°
Duration Intake @ .050” 265° Duration Exhaust @ .050” 265°
Intake Lobe Centerline 104° ATDC Exhaust Lobe Centerline 108° BTDC
Lobe Separation Angle 106° Overlap 100°
Intake Opens 52° BTDC Exhaust Opens 84° BBDC
Intake Closes 80° ABDC Exhaust Closes 48° ATDC
Intake Lift .590” Exhaust Lift .590”
Note: as installed on 104° centerline per Chrysler
'75 Plymouth Duster
Phase I 451 906/590/2-660 10.75/126
Phase II 451 Stage VI/590/1050 9.82/135
Phase III 383 906/Victor-Pump gas 11.30/119
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