[dontlifttoshift]

I use vacuum to bleed power steering and hydraulic clutch systems all the time. Not 30" of vacuum but enough to suck the air out successfully. It is the Ford recommended procedure for clutch bleeding.

My testing with drum brakes and no residual valve ended with an okay pedal and adequate operation but the pedal height was always changing. I don't have the problem when the valve is in place.

I have had enough early vette masters apart to question how they could ever hold vacuum. There must be something in the late model master cylinders to accommodate that. Next time I have a complete new system, I will apply vaccum and see if it holds.