Sounds like you're centering the brake shoes with each step on the pedal.
During the bleeding process, I like to adjust the shoes out until they just start to drag, then stomp real hard on the pedal a few times (like, 4 or 5) and then re-adjust the shoes until they just start dragging again and repeat. This will keep centering the shoes inside of the drum. The shoes are allowed to move up and down on their rests by design so they can center on the drums, but the springs hold them semi-tight so stomping on the pedal hard will force them out to a centered position. It takes a few times to get them there, and then they'll stay put.
You may have to do this a few times until they stop moving, but you'll get there and then should have a hard pedal. You should do this whenever you've removed/replaced the shoes on any drum brake.
If the pedal becomes hard BUT it still seems low, you can adjust the length of the push rod going from the brake pedal to the master cylinder. It is held captive on the pedal end (weird looking "C" clip holds it on - Don't lose it!) and it has a locknut holding the length of the plunger. Draw a reference line down the length of the piston rod and continue it onto the pedal arm clevis so you have an idea of where you started, then carefully loosen the locknut and turn the push rod OUT 1/4 turn, no more, and re-tighten the lock nut. Then, put it back together and test the pedal height. Repeat until you have the pedal up where you want it, BUT> A very little change in the pushrod length makes a big difference in the pedal stroke.
You must maintain pedal freeplay at about 1/4" - 5/16" at the top edge of the pedal. Free play is measured between the pedal/pushrod and the master cylinder piston. It cannot be measured at the MC end, so you have to measure it by pedal movement - the pedal will move easily with your hand for a little bit, then stop. This freeplay is important to allow the MC to release fluid back to the reservoir when you release the pedal. Pedal freeplay is different from where the pedal stops because the shoes get tight in the drums. For THAT, I usually expect the pedal to stop a couple of inches or more down from rest. So, pedal freeplay = 1/4", and pedal stroke is about 2" or more, OK?
I think you're close to the finish line. Just try this and see how it works.
Gordon
