Still messing with carbs, can someone educate me on Sync Set Screw?

[utgunslinger13]

So I'm still working on getting my carbs dialied in from my other thread, but I was hoping someone with more Carb knowledge could educate me a little.  In my other thread I finally got an understanding on how floats and needles work but now I'm wondering how this set screw (or is it Sync Screw?) works.

My carbs have the brass caps drilled out so I'm now trying to figure out WHAT THIS DOES lol  I currently have it set at 2.5 turns out, but could someone explain to me what this controls and how 3 turns is different than 1 turn for example.  Just trying to make sense of these adjustments I'm messing with.

Thanks,

Nick

[DoD#i]

Somone will correct me if I'm wrong, but as far as I know those screws set the air/fuel mixture at idle - turning them out more increases the fuel, turning them in decreases the fuel, the air stays pretty much the same.

IIRC (haven't had to fsck with mine) they have little effect off idle (your mains, or mids and mains for the later 3-circuit carbs) set the mixtures there.

[werase643]

it is the pilot screw
air comes thru the pilot air jet
fuel fron the pilot jet
and the mix then flows out the bypass ports and the pilot outlet
it is an air/fuel mix screw

Not a synch screw

[The Buddha]

Werase is right. Adding to that, the screw is a tapered obstruction in the fuel pathway.
Out puts less of it in the pathway, in puts more ... so out = rich.
Cool.
Buddha.