1958 Chevrolet 3200. Upgraded to power drum brakes and dual master from I think CPP. (Been a while since upgrade)
Problem: Driving along and hitting the brakes they grab well with power, but if held or reapplied right away I have to stand on the brakes. It lacks all power after one press. Any ideas? The brakes are very touchy when just leaving my drive way, but after going down the road a ways or after the first press of the peddle it lacks power.
Engine has good vacuum at about 21.5" at idle. Vacuum line runs from stock intake manifold, T's off for wipers, and then runs to the booster. Booster holds vacuum after engine shut off. Can't blow air into booster, so check valve must be working. After shutting off engine, brakes feel to have power on first press, less and less with subsequent applications.
