XJ-S V12-5.3L (1982)
Distributor Advance Unit: Testing and Inspection
Centrifugal Advance
The centrifugal advance mechanism adjusts the ignition timing in relation to engine speed. As RPM rises, piston speed increases, but the air/fuel
combustion speed remains constant. Therefore, the ignition timing must occur earlier to induce full combustion at the optimal crankshaft position. The
centrifugal advance mechanism is located in the distributor, below the base plate.
Centrifugal Advance
A support plate in the distributor shaft carries a set of centrifugal weights. As RPM increases, the weights move outwards. By means of their contact cam
and the yoke, the distributor rotor shaft (rotor shaft and yoke are one piece) moves forward in relation to the distributor drive shaft. This moves the
reluctor mounted to the distributor rotor shaft and as a result, advances the ignition timing.
