i just put in a new 350 in my camaro with a big cam and it isnt letting the motor produce enough vac for my brakes. any ideas?

 

Assuming there are no air/vacuum leaks:
Engine out of tune, spark timing, idle speed adjustment, fuel mixture adjustment
Valve lash needs adjustment
Leaky or damaged valve
Too much cam for the engine
Compression too low for cam used
Restricted exhaust

 

yeah how big is big???