67 dart front disc upgrade made..still not right

grumpuscreature said

That is what MaMopar used to hook the brake pedal to the booster. By design it gives you an increase in mechanical advantage over a straight pushrod, meaning you don't need to press as hard on the pedal. If you don't have that, your power booster is not going to be as easy as you want.

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Backwards description. That lever applies less force on the MC (and more travel). That is why the factory MC on power brake cars has a smaller diameter bore than a manual MC. Some people think that is backwards, but not when you understand the lever arrangement. Lookup (rockauto) the factory MC size for power brakes for your year to get an idea. I would think a 7/8" MC is close, which would be 40% less pedal effort than your 1-1/8" bore (can anyone else calculate that?). I put a booster and MC from a Breeze on my Dart (7/8" MC, I recall). I still have the front drums. The brakes are a little too touchy now, but should be perfect when I change to front disks. For now, I have to learn not to press too hard and skid. If still no luck, take the booster off and move the rod by hand while connected to engine vacuum and see if it follows your motion without much resistance.