WHO'S GOT THE SCOOP ON RESIDUAL VALVES?

In the late sixties and early seventies Brake companies began using metal expanders on each end of the springs.
The expanders pushed the rubber cups tightly to the wheel cylinder bore which made residual valves useless.
It took a few years before, the residual valves were completely discontinued.
No harm in leaving the valve in the master cylinder but they are no longer needed unless you have some really old wheel cylinders.
Most wheel cylinder kits now come with expanders including the old cars from the forties and fifties.