You know how it says to "Never change hex head screw adjustment" in the Carter BBD operations manual and FSM? I think it has been changed at some point in the past and would just like to confirm that it is in the optimal setting.

My question is, what does this setting really effect and what should I be looking for if the setting is correct/incorrect. My plan is to move it by 1/4 turns in either direction and drive it. Is this an effective method or do I need to get the carb flow tested to have it really dialed in?

We used to do this for drivability when I worked at the dealership when they first came out. That was late 70's early 80's so my memory is foggy but I do think that you turn it in clockwise. Now if my brain (cells are mostly gone)is correct I do believe we ran them in fully. The cars came very lean from the factory to pass epa standards. Now my boss did alot of strange things to sell cars back then so some may disagree with this.

The screw is used to adjust the drop of the meter rods. Screw it down and it leans the mixture, screw it up and it richens the mixture.

Thanks for the input, I ended up turning it in 1 full turn (leaner) and it made better high end power but low end seemed slightly worse. I'll keep experimenting. It is pinging slightly.

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'63 Valiant 200 2 door hardtop, 225 stock rebuild with super six set up, carter bbd, hei mod, 3spd manual on the column