Francis if you will put the master cyl on and fill it with fluid, then just push the brake pedal down slowly about an inch and let it back up with filler cap off and looking down into the fluid you will see air bubbles coming to the top of the fluid. This is the air escaping back through the fluid.when you just barley move the piston in the master it opens and closes the system to a small bleeder hole in the master cyl. If you will watch in the master cyl resovior while your moving you will see the air escaping. i have had good luck bleeding this way if the problem I repaired was just with the master cyl on the single cyl brake systems....Ronnie