Classic/Antique Car Repair: 68 Mustang Brakes, power brake booster, mustang gt

Question
Dick, I have just replaced the power brake booster and master cylinder on a 68 Mustang GT convertible. Unfortunately, now the brakes drag until the pedal is lifted up. Is this due to the adjustment on the booster push rod to the master cylinder? If so what is the correct way to adjust the push rod?

Answer
It could possibly be the rod adjustment, but since you can get them to release when you lift the pedal, I think more likely your pedal return spring is too weak, or there is too much slop in the parts.  The right adjustment is when the pedal has to move about 3/8 of an inch down before the rod contacts the piston and causes the pressure to start to build - and I'm not sure your car even has an adjustable rod length.   Investigate that spring that holds the pedal up against its stop when your foot is off the pedal - I think when that is strong enough, and there is no loosness to the parts, it will be OK as is.

Dick