If you were sold the correct dual master cylinder for a drum/drum system it should already have a built in residual valve. There would be no need for more additional residual valves. That may be part of the problem. Fred
1956 3100 Pickup/Red/350/3sp OD/PS/Disc Brakes 1957 Bel Air Sport Coupe/Red/355/TH350/PS/Disc Brakes 2017 Silverado LT Single Cab SB/Black/5.3/6 Speed Trans 1947 Willys CJ2A w/F-Head engine
