quadrajet idle speed adjustment

[greggome]

My 68 327 has a referbed quadrajet on it. My mechanic had this thing set to idle at 600 rpm. I want to adjust it to idle at the proper 750 rpm. I understand there are 2 idle speed screws, the base idle screw and the fast idle screw. I'm familiar with Holley carbs but the quadrajet is confusing. How do i set the proper idle on this carb?

 

[LLC5]

My 68 327 has a referbed quadrajet on it. My mechanic had this thing set to idle at 600 rpm. I want to adjust it to idle at the proper 750 rpm. I understand there are 2 idle speed screws, the base idle screw and the fast idle screw. I'm familiar with Holley carbs but the quadrajet is confusing. How do i set the proper idle on this carb?

The base idle set speed screw is on the left side of the carb (driver side) and the two fuel mixture screws are at the front of the base plate. The fast idle set speed screw is on the right (passenger) side by the choke.

 

[greggome]

Yes I know the location of all the screws on the carb but with 2 different idle screws how do you adjust them to achieve a consistent 750 rpm when motor is warmed up?

The base idle set speed screw is on the left side of the carb (driver side) and the two fuel mixture screws are at the front of the base plate. The fast idle set speed screw is on the right (passenger) side by the choke.

 

[Antz81]

Yes I know the location of all the screws on the carb but with 2 different idle screws how do you adjust them to achieve a consistent 750 rpm when motor is warmed up?

Once it's warmed up just adjust the base idle screw.

 

[Les55]

My 68 327 has a referbed quadrajet on it. My mechanic had this thing set to idle at 600 rpm. I want to adjust it to idle at the proper 750 rpm. I understand there are 2 idle speed screws, the base idle screw and the fast idle screw. I'm familiar with Holley carbs but the quadrajet is confusing. How do i set the proper idle on this carb?

You turn the idle mixture screws in all the way. Then back them out 1 3/4 - 2 turns, both screws.
Start the car. Adjust the idle screw (automatic transmission 650 rpm) (standard transmission 750 rpm).
Then turn the left idle mixture screw out untill highest rpm is achieved. Turn back in (for lean idle adjustment) 1/4 turn.
Adjust idle back to 650 auto/750 standard.
Now adjust right idle mixture screw out to highest rpm. Turn back in (for lean idle adjustment) 1/4 turn.
Reset idle adjustment screw to 650 auto/750 standard transmission.
This is standard for all quadrajet carburetors.

Sent from my SM-G930V using Tapatalk

 

[LLC5]

Yes I know the location of all the screws on the carb but with 2 different idle screws how do you adjust them to achieve a consistent 750 rpm when motor is warmed up?

You do not adjust both set screws when the choke is fully open and the engine is hot, the only adjustment for a hot idle setting with the choke completely open is the base idle speed set screw on the left side of the carb.

If you have an electric idle stepper/kicker solenoid (not sure if '68's had them) then you would set the desired idle speed with that solenoid, but first you would disconnect the solenoid and set the base idle lower by about 100 rpm's with the set screw on the throttle linkage, then plug the stepper solenoid back in and set to the desired idle speed using the solenoid.