I have changed my m/cyl on my 49 Chevy, bled brakes, I can get pedal hard and it holds,not spongy. But if I release pedal and then push down on it again it goes to floor. I don't understand. Is it a faulty master cylinder? No leaks in system. Thanks
Sounds like your brake shoes are too far from the drums and need adjusted up some. Also check the free play in the actuator rod from pedal to m/c. If you got a m/c with no residual pressure valve (like disc brake m/c's) to hold shoes close to drum between brakings the pedal has to be pumped till shoes contact drums. This can be fixed with 10# inline residual pressure valve.
Randy ; Your brakes have TWO brake shoe adjusters at each wheel...... Most often this is the fault you're describing .
