273 carter afb

When I disconect the vacuum line in the front of the carb the one that gos to the distributor it seems to have full vacuum at idle the same as the one that gos to the choke pull off. Its a carter afb 4v I know the distributor vacuum should rise as the rpms rise. Cant figure what the problem is. The carb is a 1965 273 4v stock carter afb