I hope some all dogs are still left alive and on this forum, LOL! I have a 1971 Chevelle I bought for my daughter. I went to classic performance parts and bought front disc brakes for it and had them professionally installed. They worked really great at first, they were strong and would stop the car on a dime. Now it feels like I'm pushing a brick when I first first apply they brakes, then they start working, sluggishly. I put a new proportioning valve, a new booster and had the brakes checked by three different auto places. I'm running the vacuum straight from the booster to the back of an Edelbrock carburetor four barrel. They still just don't seem to be working right what else can I look for that could be causing a problem where they didn't used to be one? My daughter just turned 17 and I hate to take his car away from her because I can't make it safe .. My vacuum is running low, around 16-18 psi. I've been told that I could put a vacuum pump on it, but that still doesn't explain to me why they worked so great at first and now they don't. Any advice from any of you guys in the know?

 

How old is the booster? I'd suggest that might be the problem, are you expirencing any performance issues that would involve a vacuumj leak?

 

Take the vacuum line off the booster with the engine running. If the engine dies out your carb is too lean. If it speeds up your carb is too rich.