I just had my brake booster rebuilt on my 57 olds and bled the system and bench bled the booster and adjusted the brakes. When I first step on the pedal it goes to the floor and then after 1 pump it is perfect, any ideas why it is doing that?

 

Air in the system and brakes may need adjustment.

 

Bked the system 3 times. No air bubbles came out and already adjusted brakes

 

No air or vapor can escape from a closed system. Even if you can get the bubbles to dissolve in the fluid as soon as the pressure is released and the brakes heat up the fluid, those air or vapor bubbles will be right back again.