Pulling V.A at idle

Something I haven’t seen mentioned here but does vacuum can on distributor have adjustment in inlet
(Allen screw in tube) . It is my understanding that it can be adjusted to set when vacuum advance comes into play. Possibly a new can not adjusted or one messed with.
This may have been mentioned before and I missed it.
Don’t take this information as gospel as many on this forum know way MORE than I do . Just a thought.
Yote