:mad: In 1999 I picked up a 69 that had power brakes added by the previous owner. The reason I knew the brakes had been added, is the lines appear to have been changed from the original positions that attach to the proportioning valve and also the wire that attaches to the valve had been cut. Also the front calipers had been ground to fit behind a 14" Rally Wheel with a spacer. When stopping from speeds above 50 mph it seems that I almost need both feet to stop and I'm not sure that I could even lock up the wheels if needed. I have checked the booster and it seems to be functional according to the tests that were listed on MPBrakes website. I have a 75 Malibu Classic that when you touch the brakes, they will almost put you through the windshield so I know that stock systems will work. I have no idea if the master cylinder is correct on the 69 as I can find no numbers to cross reference the unit. I'm considering purchasing a new booster and cylinder was wondering about the dual diaphram boosters. Anyone offer any advice as to a solution to my problem. I really don't want to purchase new spindles, rotors and calipers.

OK I know some of you here can help me, come one lets hear some suggestions. I'm not really sure how many inches of vacuum I have, I'm running a small roller cam around .452ex and .436in. I'm not sure if I need to go to an electric vacuum source or if I need a new booster or master. I see cars all the time with a more radical cam that I've got and they don't have an electrical pump, so how do they do it?

Its very likely a bad master cylinder...if you don't know where the part came from youre better off ordering a new system so you can be sure everything is right