I installed a disk brake kit on the front of my 70 nova with a new master cylinder and power booster. When i press on the brakes it sounds like i have a air leak under the dash. What could be causing this???? Any help would be very thankful.
Did you replace the vacuum hose when you installed the new booster? You could have a loose hose, or a cut in the hose. Or a bad booster, like mentioned before. Even new ones are sometimes bad. When the car's running, is the brake pedal hard to push? Test your booster - Turn the car off, pump the pedal to remove remaining vacuum, and with your foot on the pedal, start the car. You should feel the pedal drop just a little from the incoming vacuum. If not, then I'm thinking you have booster problems. If your hearing a hissing though, I'd say you have a vacuum leak somewhere.
The pedal is alittle stiff. I put a new booster on the car when i did the conversion. I also replaced the vaccum line that runs to the booster. But there is a hiss when i press the brake pedal. I will try what you said.