The hell they won't. I had a defective Quick Fuel carburetor that had an internal vacuum leak and I couldn't get it to idle come hell or high water. Sent it right on back. The next one worked fine.
I'm not quite ready to send it back...this could (probably) is me. Haha! I'm not that familiar with Holley style carbs, though this carb is a lot different from the 4150/4160.