Let me start at the beginning. For the last couple of years I had noticed that my vette a 69 big block would pull to the left when I would apply the brakes. So last summer when I got it out it did the same thing. So me being typical "Oilfield" I locked up the brakes to see if that would help it to stop pulling to the left,"Not the thing to do"! What happened was now I have one brake on the front and one on the rear that will not release till the car sets for awhile.I was going to change all the wheel cylinders but I was talking to a mechanic and he said that the problem sounded to him like it was in the master cylinder. Has anyone out there had this same problem and if so which parts should I change? The master cylinder or the individual wheel cylinder.
George

yeah I had a similar problem on my last vette..

I just wound up replacing the calipers (LF, RR), they were pretty nasty and had some leaks anyway. If you had this problem on both front or both rear I would say proportioning valve or master cylinder first. but since it is both on a side.. I would lean toward coincidental bad calipers. I just bought a couple of rebuilt ones from one of the vette mags and was happy with them.

also if youre going to have the calipers off.. let me highly recommend the stainless braided hoses... they firmed the brakes up nicely.

It is not the master cylinder. The two chambers of the master cylinder operate front and back. Newer FWD cars use a X pattern, one front and the rear on the other side for each master cylinder 1/2. Not our C3s. The master would cause both front or both rear brakes to lock.

Also, you have no wheel cylinders. You have four brake calipers. Wheel cylinders are used with drum brakes.
Our C3s have a somewhat unique caliper. Instead of moving side to side as most do, ours are fixed solid in place. Each caliper has four pistons, two on each side. A hard brake application can cause a sticking piston to extend, and stick, causing brake drag.

The sticking will also cause uneven braking, even if they do not cause drag. You likely need to rebuild or get rebuilt calipers. You could also have bad brake hoses going to the wheels, which could also cause erratic braking.