Avs on my 383. When I open the throttle, the ported vacuum creeps up slow. When I close throttle, vacuum remains.

Welcome aboard! that is a strange case. you might blast a shot of brake kleen or starting fluid into the port to clear it out as it possibly might be partly blocked. which port are you on? if you pull the vac gauge hose off of the nipple it jumps right back to zero correct? how much vacuum are we talking about?

I suspect your gauge or hose is bad as the vacuum is created as air passes by a small opening in the bore As the throttle opens the air flow increases thereby increasing the vacuum, as it closes the vacuum has to drop.
It is a remote possibility that something in the passage is acting as a check valve but that would be a strange anomaly

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The gauge works on other ports. The port will not blead down.

Assuming we are talking about the port on the R(passenger side) "FRONT".
Then there is something in the port that is acting like a check valve.

Pulled the carb and used a straight pin to clean the passage. Now it works. Should just rebuild the carb, or have it done.