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Yes. There are books dedicated to the Rochester Quadrajet.
You can buy a kit with new jets and metering rods for this purpose. Quadrajets can be a little tricky, so you might want to get a how-to book and read up on the procedure.
If it a Rochester carberator, there is no mixture adjustment. That is an internal setting done when the carburetor was put together or at the time of rebuilding. The only adjustments you can make is to the idle and choke I have a 93' 2500 vandura and It failed smog and I advanced the Timing a tiny bit and it passed....yaaaaay
The fuel mixture is controlled by the computer and is not adjustable.
Turn Drivers side fuel mixture screw CW until it Stop turning. (Lightly do not over tighten) Turn Fuel mixture CCW 3 turns then stop. Do the same on passengers side. Start engine Turn mixture screw as before CW until Engine Starts to stumbel then back out 1/4 turn. Do the same on other side. set RPMS ur good 2 go
Computer controlled
adjust the two fuel screws all the way in and adjust a half turn out until you get it right
If it's an EFI engine you do not adjust the mixture screw. The mixture is computer controlled.
They are to adjust the air/fuel mixture.
torque specs air fuel mixture screw on a yz125 2003
Fuel mixture can not be adjusted it is computer controled.You can adjust the idle by removing the cover where throttle cable attaches to the throttle body and turning adjustment screw
Start at 1 1/2 turns from seat and adjust until you get the best idle