Dave and Steve,
No, there is nothing wrong with your carb because it shows no vacuum at
the
brass vacuum advance port when you check it with the engine idling. This
port doesn't get vacuum until the throttle is at least part way open. These
1969 cars had both vacuum advance and retard, and the retard unit was
actuated off of manifold (rather than carb) vacuum. There is a vacuum
switch on the throttle bellcrank that opens and closes the vacuum line to
the retard unit, so that the spark is only retarded when the throttle is
closed (at idle or coasting). If the advance unit were also getting vacuum
at this time, the two vacuum units would be "fighting" each other, probably
resulting in neither advance nor retard. Once the throttle starts to open,
the vacuum switch shuts off vacuum to the retard unit, and the vacuum port
in the carb starts delivering vacuum to the advance unit.
Rex Townsend
CC26713L
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