How much should the drum be able to spin when the
rear brake are adjusted properly?

I think in the front disk brake setup the wheel should turn around once with moderate force. How would you adjust the front? Loosen the caliper pins perhaps?

Thanks

There is no adjustment in disk brake applications. The piston seal is a square-cut seal and the natural action of the seal causes the piston to retract just the right amount. As for the rear drums you should adjust the shoes until there is a moderate amount of drag. This is really a learned feel, but if you rotate the drum and you can feel and hear slight drag then it really is close enough.

Thanks Erik,

I was reading a 74 Buick manual today and they
have a procedure involving removing a piece in the backing plate. Then you can fit a adjuster tool in that area.
I assume the feel test on the drums is done with the tire attached. I know that drums are self adjusting but I guess if they are too out of adjustment then adjustment is more difficult.

If the pads are brand new is some drag to be expected?

I usually check the drag with the wheel off. Just turn the drum by hand and listen and feel for drag. If you back off the adjuster until there is no drag, then adjust it until there is a slight amount of drag and you can hear the shoes on the drum (slight amount being that with two hands it takes a small amount of force to get it to turn...it is hard to describe). The self-adjusters should take care of the rest. I think that the procedure you are talking about might actually be for adjusting the parking brake.