Should the vacuum canister on the right front of my carb hold a vacuum.  It's the choke pull off I think it's called.  I used my Mity Might vacuum tool to pull a vacuum on it and it sucks the diaphram in but it then leaks back out.  Should it hold a steady 10 or 15 inches of vacuum?

The pull-off valve has a "controlled" bleed, so it should not hold vacuum. It should bleed off slowly. If it bleeds quickly, it's prolly no good, but if it takes a few seconds to slowly release, it's ok. 

That's kinda what it does.  Pump it up to about 15 inches and it takes about 2 seconds to bleed off, it's not instantaneous.

2 seconds might be a little fast....Imma tinking more like 4-5, then slowly release... been so long since I worked on one, it's hard to remember....
I'll look at some of my old stuff and see if I can find a spec for the pull-off.

A quick look here came up with this...no specs, but it does confirm there is a delay(bleed) in open/closing of the pull-off....



|UPDATED|9/18/2013 10:05:10 AM (AZT)|/UPDATED|

General rule of thumb is if when you start the car it pulls right away, and maintains the position while running, it is probably okay.   If you open the 4 barrel you can expect it to drop due to lack of vacuum.