Got to the trial fit of the manual master cylinder on my 66 last night. This is the Ground Up kit, less the booster.

After pulling the old single resevoir, it seemed the pushrod to the pedal was too long. The Ground Up tech did not seem to know about the pushrods, and referred me to Right Stuff, who had a suitable pushrod/clevis available. So I ordered one, and then found a shorter one in my stash of stuff.

Then, while measuring the two, I noticed that there is a machined spacer plug in the new one. When I took it out, it made up for the difference in length of the pushrod.

So, with a slight adjustment on the pushrod at the clevis, it all seems to fit.

Anyone else have experience, and, or can shed some light on this?

Most power brake masters have a slightly larger piston bore and the hole in the back where the rod goes is much shallower (about an inch).

Manual brakes generally have a smaller piston bore and the end of the piston is bored out to support the rod. This is just to keep the rod from falling out of the master when you let off the brake pedal.

I found that the piston pin on a Delco Moraine booster will pop right out and it can be exchanged from long to short, or short to long.

The master I just got for my 66 (using 67 PB/Disc master and 72 booster) had a deep bore in the piston and the booster had a short pin----bought a long pin for the booster and all is good.

Also bought a bushing from CPP, but it is a larger diameter than the bore in the master.

I suppose the pins and bushings are available so one can custom tailor his brake 'feel'.