[MXTex]

The power assist feature of my newly installed brake system is not working. The system is comprised of four wheel discs (C5 up front, LS1 out back). All new lines. New 9" booster, proportioning valve and dual MC. The car is a 1965 GTO. The engine is a 428 with Lunati Voodoo 703 camshaft. It makes 11.5" of vacuum at idle. I realize this is not enough for proper operation of the brake booster. But my issue is there is no power assist at all. I can rev the motor up sufficient to create 18" of vacuum but still no power assist. None at all. The car will stop but takes GREAT effort. Clearly a vacuum pump and/or vacuum reservoir are in my future; but I'm not convinced that my booster is good. Let me explain. In troubleshooting the booster I reached a point where I needed to check to see if it would hold a vacuum. First I attached my mityvac hand help vacuum pump to it. And no matter how much I pumped it, it wouldn't even start to pull a vacuum. Then I simply used my lungs. I pulled on that hose as hard and long as I could and received no resistance at all. Then I hooked up a small electric vacuum pump I have to it and let it run. Still no vacuum whatsoever. And finally, with the engine running and vacuum hose attached to the booster, I removed the vacuum hose from the booster and noticed that the idle didn't change. Then, after placing my finger over the end of the open vacuum hose sealing off the leak, the idle quality changed significantly. So with this information, I was convinced that I had a bad brake booster so sourced another one. I received the new booster yesterday and tested it on the bench before installing. The test results for this new unit were identical to the other. It won't even start to hold a vacuum. Not with the mityvac, my lungs, vacuum pump, or engine vacuum. Nothing. So now I am at a quandary. What are the odds that two brake boosters in a row could be bad in this way? Is my testing rationale? Should the boosters hold vacuum? Do I need to try a higher quality booster? Admittedly, these were the cheapest I could find. Thank you.