Holley HP 4150-Type Mech Carb Discovery.

[72step]

I recently installed a QFT Mech 650 Carb on my truck recently, which is pretty much a Holley Ultra HP or Pro-Form. I'm pretty new to this type of carb. I hadn't had even a holley in 20 years. Today I was fine tuning it, and was having trouble, it was acting like the timing was too low, but I checked the timing and it was 18-19 deg. as to specs for my cam. Finally after messing with it a while I made the discovery that the fast idle screw goes like to zero and into the negative, and it was set like into the negative from the factory, therefore it was stumbling and backfiring. Once I discovered this, and finally adjusted it into the positive idle, it ran like a bat outta hell, it even sounds like it should with that mean idle. Is this normal on these carbs, or did I just discover that?

[rage'nrat638]

Is this normal on these carbs, or did I just discover that?

what?