I have a 68 Malibu that as far as I know originally had power drum/drum combo. I purchased an installed a complete power disc set-up with new spindles, calipers, new lines, master cylinder, and 7" dual booster. The car stops horribly ..... with a super stiff pedal that has no feel to it. As hard as I can possibly stomp the pedal, I can't even get it to lock up (front or rear), or feel comfortable with a quick stop if I have to.

I checked vacuum and have ~15"-16" - and don't suspect that the cam is wiping out the vacuum. I have an adjustable proporting valve that came with the kit installed on the frame line that goes back to the rear drum brakes.

I'm beginning to suspect that it may have something to do with the valving. I read about a two-stage valve (I guess one for proportioning and the other for distribution ????), and a single combo valve, but I'm still confused on what I should have and need. I still have the original distribution block installed on the frame near the firewall.

Does anybody have thoughts as to what problem I might have with the system? Do I need to purchase one the combination valves? Keep the original distribution block??? I'm at a complete loss ...... thanks for any help.