Master cylinder-what this hole?

Stangboy67

New Member
Aug 26, 2005
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Lynnwood, WA
I'm setting up a late model power booster/MC install in my '67 and I have a question or two. What is the hole on the bottom-center of the master cylinder for? It is right under the rear brake line port, "pointing" strait down, threaded and looks as though a brake line would screw in here? It is also wet with what appears to be brake fluid. I have a photo, but couldn't figure how to attach it.

Unfortunately I was not the one who removed it from the car and I don't have access to a late model to peak at for a visual reference. Also, are the brake line ports on the mc the same as the early model, ie front port on the mc is for the rear brakes? TIA