Idle Mixture Screws

[59bluesilver]

Something doesn't quite make sense to me. The air mixture screws in this quadrajet shown below are both 1 3/4 turns from the seated position. However, the right one extends much further into the venturi than the left one. Is that the way it supposed to be?

[Frank400]

could be two things.  You may have mismatched idle mixture screws.  I've seen different tapers thu the years. And/or, the idle discharge hole may not be the same size on both sides.  I've seen it on virgin carbs.  Have you measured both sides idle discharge holes ?

[59bluesilver]

The screws are the same length as is the springs.

[Jeffs68]

I don't think it matters. When you are making your adjustments, turn each one in, one at a time until the engine starts to run rough and Revs drop, then back it out 1/2 to full turn. You can use a vacuum gauge to assist, make adjustments that will give you the most vacuum possible.

[59bluesilver]

I guess I don't understand what the taper does or its function. There must be some reason why it extends into the Venturi, or not. Can someone explain it to me?

[Jeffs68]

That additional air bypass hole may have something to do with it?

[59bluesilver]

I guess, it's the only thing that makes sense.