Combination valve malfunction??

[slikside]

I've done a search, and found some good info, but none of the scenarios were exactly the same as mine, so here goes.

'72 C10 disk/drum. Just finished a complete brake system overhaul. The only part between the pedal pushrod and the pads that isn't new/rebuilt is the combination valve....but it is new to this truck.

I sent the calipers, master cylinder, combination valve, and vacuum booster out to be overhauled. The shop said that my combination valve was shot, but they had one just like it and gave it to me for the price of overhaul. The pin on the metering portion was in, and they said it would pop out after the bleeding process. Well, the bleeding took a while, but we have a firm pedal. Hooked up the wire to the warning switch and had the red brake light on. Pushed hard on the pedal, and the light went out. But here's the thing, the pin on the metering valve has never popped out. It was clamped during bleeding as the procedure calls for.

I do have brakes, but they feel about the same as they did before all this work! Very difficult to get it locked up on the pavement. Found a little dirt road nearby and slammed on the brakes there. The rears are locking up (not prematurely) but the fronts are not.

I have the factory service manual and have read all about this valve. I'm thinking this "replacement" valve I got might not be any better than my original, which they said was junk. The truck just doesn't stop as well as I think it should, and even though my brake (idiot) light is extinguished, that pin on the metering valve has never popped out.

So what do y'all think? I appreciate all your input.