This is my first posting,though long time visitor. I have drums all around, no power on my 72, which I rebuilt earlier this summer and have run great till a week ago. Now the peddle goes to the floor and I can barely stop unless I pump it before I reach a stop, then it stops fine. Could it be the mc ? thanks

More likely one or more of your wheel cylinders is leaking and letting air into the system. Pull the drums and take a look before you spring for a new MC.

I had the same problem with my 71 Chevelle... I did a manual to power brake conversion correct to that year and eliminated my problem instantly..Just like Xtreme70SS396 mentioned double check all components before purchasing a new unit.. smile.gif