My new 78 crew had a newer booster and master cylinder but they were for single piston calipers instead of duals so I swapped them out for the correct ones today. Bench bled the cylinder and vacuum bled the lines. Had lots of pedal and it felt great so I took it for a test drive down the road and back, roughly 1.5 miles round trip. By the time I got it back the brakes were hot and all 4 wheels were tight. Jacked it up and can't roll the tires by hand. Any suggestions? Do proportioning valves go bad? Could I have sucked something into the valve and plugged an oriface with my vacuum pump? Did I just get a bad master cylinder? I did crack the fitting for the front brakes and it freed up the front to where I could roll them by hand. Didnt do the same for the back yet (wife was holler'n to get cleaned up for supper) ill try it in the morning. Am I on the right track with a bad, new master cylinder or what?