What master Cylinder To Use?

1970 Dodge Charger originally came with power drum brakes. Was converted about 35 years ago to power front disc brakes. I built a motor about 15 yrs ago and didn't have enough vacuum for power brakes so I pulled the power booster out and been running manual disc for yrs. It's time for a new master cylinder and wondering which one to use. I am using Raybestos #7008 10.97 rotors and the Raybestos #RC4065-66 single piston Caliper all for a 1970 Dodge Charger. I was told to use 15/16" Master Cylinder MC36406 off of a 1973-1975 A Body. I was also told to use a 1" Master Cylinder MC36400 off of a 1973-1977 B Body. Any suggestions?

Smaller MC piston in my opinion always best for non-PB system. I run a 15/16th on my E Body, disc brake,,,, much better braking than previously installed 1 1/8th MC,,,it was miserable. Gave me sufficiently greater brake clamping force that was able to switch from nasty dirty pads to very clean ceramics.

I ended up going with the 15/16" master cylinder. Won't be able to install it until next month. I am also changing the Proportioning Valve at the same time.

Agree with the 15/16" diameter with manual discs. Dr Diff has one in aluminum which would save some weight.

Hopefully the brake linkage was changed out when the power brakes were removed. The manual linkage gives more leverage for use w/o booster.

I have a 15/16 with Viper front calpiers and rear drums with an original drum/drum proportioning valve. Works excellent.

Looks like you've already purchased, but was gonna ask, what size did you have and how did you like the pedal feel?

I don't know exactly what master cylinder I was using but think it was a 1 1/32. I ended up getting a 15/16 but haven't installed it yet. It wont be for another month. I have been talking to Dr Diff about my whole brake system.

I had an alumnium mopar MC 1 1/32" and i just have replaced it for a 15/16" cast iron Dorman unit (73-76 A body)
I haven,t run the car yet, but at least the effort and the pressure on the front calipers are the same as the 1 1/32 mc.
1500 psi with both MCs ,pressing the pedal with all my force(manual brakes)