[dwcsr]

For the life of me I don't know why this residual valve thing keeps alive.
You only need a residual valves IF and only IF the master is below the wheel cylinders. Most masters don't have them, very few during the 80s and some earlier did.

If your stock height don't use them. The stock system doesn't have them and changing the Master doesn't create a need for them.

Hotrods started using them because the master was on the rail that was several inches below the wheel cylinders.