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DISTRIBUTOR—Description and operation
The distributor (Fig.107) has two independently operated spark advance systems. A centrifugal advance mechanism is located below the stationary sub-plate assembly, and a vacuum operated spark control diaphragm is located on the side of the distributor base. As speed increases, the centrifugal weights cause the cam to advance or move ahead with respect to the distributor drive shaft. The weights turn the cam by means of a stop plate that has two slots, which fit over the pins in the weights. The slots determine the maximum amount of advance and the rate of advance is controlled by calibrated springs.
The vacuum advance mechanism has a spring-loaded diaphragm which is connected to the breaker plate. The spring-loaded side of the diaphragm is airtight and is connected through a vacuum line to the carburettor throttle bore. When the throttle plates open, the distributor vacuum passage is exposed to manifold vacuum, which causes the diaphragm to move against the tension of the spring. This action causes the movable breaker plate to pivot on the stationary subplate. The breaker point rubbing block, which is positioned on the opposite side of the cam from the pivot pin, then moves against distributor rotation and advances the spark timing. As the movable breaker plate is rotated from retard position to full advance position, the dwell de-creases slightly. This Is because the breaker point rubbing block and the cam rotate on different axes.
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Distributor points—to check, adjust or replace
Unsnap the distributor cap retaining clips, lift the distri-butor cap off the distributor housing, and position the cap out of the way (if necessary, remove the air cleaner and/or the high tension wire to gain access to the distri-butor).
Lift the rotor off the cam.
Inspection
Replace the distributor point assembly if the contacts are badly burned or excessive metal transfer between the points is evident. Metal transfer is considered excessive when it equals or exceeds the gap setting.
Removal
- Remove the primary distributor lead connector wire.
- Remove the screw attaching the ground wire to the distributor point assembly.
- Remove the screw nearest the distributor points, then remove the distributor point assembly.
Installation
When installing new distributor points, reverse the procedure for removal and make sure that the ground wire is attached to the distributor point assembly attaching screw which is furthest from the distributor points.
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