I have searched for quite a while and can't find the thread that had a picture looking down into a Corvette style master cylinder. It showed how it was drilled to let the fluid into the piston and how the ports were spaced differently so you could tell which went to the front and which went to the back. If someone knows of the thread or could post the picture please do so I need the info. Thanks Brian.
What year is the master for. Vette masters should be disc disc after 1965 or so. I'm guessing you're using 1970's style vette master. If that's the case front reservoir is front brakes. Is your car using disc / disc. If not you will likely need a proportioning valve for rear drums when using the vette master designed for disc /disc.
Last night I was bench bleeding a Corvette m/c. I noticed that brake fluid started moving in the front chamber first. That would mean that it goes to the front. Someone correct me if I'm wrong , that's an easy way to check any m/c to see what chamber start to move the brake fluid first.
Just remember that if the master is under the floor as opposed to being on the firewall everything is backwards or flipped, the back becomes the front and so on.
The larger reservoir, if it has one, always goes to the front brakes. Some have both the same size so it shouldn't matter too much on those. Every stock master I have ever worked on used the one closest to the pedal for the front brakes, but I can't say all of them are that way.
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