Jason---The vacuum retard works as follows:
There is a spring-like attachment link connected to a post on the plate
that the points mount on.
The post attached to the points plate is connected to the vacuum retard
canister, via this link.
When vacuum is applied to the canister, it pulls the points plate
counter-clockwise, delaying the opening of the points, which retards the
ignition timing. The amount in which this action retards the timing is
16 degrees.
If you feel vacuum at the end of the hose, which originated at the
bottom of the back carb port, it should pull the points plate, as
outlined above. If it doesn't, there may be a leak in the retard
canister. This can easily be checked by taking the distributor cap off
and applying vacuum to the canister from an outside source. You should
see the points plate move CCW.
It's also possible that the points plate is frozen in place for some
reason.
Dick
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