The problem is the size of the piston in the master cylinder. Drum type master cylinders run a smaller size piston (3/4" to 1") than a disc type (1-1/4" or so). This is due to the higher operating pressures and less volumn than discs. If however, you have a nice fat booster, say 8 inches plus, then you can get away with it. I would forget about this metering valve. You will need higher pressures for the drums and a metering valve is not going to help. Good luck.
