Porsche 928 Workshop Manual page 525

928
Ignition System
28
The distributor for USA/Canada/Japan models has a vacuum box for advance control beginning with
1983 model.
IGNITION ADJUSTING AND TESTING VALUE - USA/CANADA/JAPAN
BEGINNING WITH 1983 MODELS
Ignition timing
(without vacuum)
20' BTDC at 3000 rpm
Idle speed 650 f 50 rpm
Centrifugal control
4 to 8' BTDC at idle speed
(without vacuum) 24 to 28' BTDC at 5000 rpm
Vacuum control Produce approx. 400 mbar
(at idle speed) with manual vacuum pump
"Advance" 13 to 17O
Printed in Germany VII, 1983
Ignition Adjusting and Testing Value -
28-33
USA/Canada/Japan 11983 Models)