power Brake issue.

[kellyavanti]

my '63 Avanti (R-1880) has developed a brake issue. It stops fine, with plenty of power assist. When sitting at a stop, just applying enough pedal pressure to hold the car, I hear a vacuum leak, and it's big enough that it makes the car miss. Push the pedal harder and it stops running rough. New booster time? I've checked the hoses for leaks... Thanks for input.

Kelly

[Gunslinger]

It may not be the booster...check the large rubber tube between the carburetor and the booster.  Disconnect the hose at the booster and the engine rpm's should rise...plug the hose and the rpm's should lower and stabilize.  If it doesn't, the hose is bad.  The fitting where the hose attaches to the booster could also be cracked.

It is just as likely the booster has gone bad internally.