I'm still around and still working on my old cars.  My 56 Fairlane has drum brakes, I had them rebuilt,  It is a vacuum assist system.  When I first start the car the brakes are horrible, but after a couple of miles the car will stop on a dime.  I suspect the vacuum cannister is bad or out of adjustment.  Can I adjust the cannister?  any ideas would be greatly appreciated.
John

The vacuum check valves in the system would be at the top of my list.

Lorena, Texas (South of Waco)

I have had a vehicle in the past that the supply line connection at the intake was partially clogged.
Make sure you have good supply of vacuum to the booster.  

Located in Harford County Maryland 

Thanks, I will check out both suggestions.

It was the cannister, the brakes are working great now. 
Thanks