[jr19661966]

Howdy y'all here's the deal I have a 1966 impala hrd top it has factory power brakes that I have compleatly gone through (new lines wheel cylinders shoes springs master cylinder and drums) the only thing I changed from factory is replaced the single master cylinder to a duel master cylinder from a 1972 chevy truck. I did this swap in my 66 chevy truck and it worked perfect but this ones giving me problems. I have bled them numerous times to ensure no air is in the lines no leaks no loose connectionyou and have adjusted them to spec. I have pressure at the bottom without the brake booster but when it gets almost to the floor it kinda pops and hits the floor? At that point hold on cuz you ain't stopping almost like you took your foot compleatly off the brakes. If I hook up the booster it goes straight to the floor with just a little resistance. Any suggestions?