Turn them fully in and then 1 1/2 turn out. This will allow you to start the engine and fine tune them from there.
Could be the idle is set too high, maybe the mixture screw passageways are plugged up.
To adjust the fuel mixture on a Rochester Quadrajet carburetor, locate the mixture screws on each of the primary side throttle bodies. Turn the screws clockwise to lean the mixture and counterclockwise to richen it, making small adjustments while monitoring the engine's performance. Ideally, adjustments should be made with the engine running at idle and using a vacuum gauge or exhaust analyzer for optimal tuning. Always make incremental changes, allowing the engine to stabilize after each adjustment before proceeding.
rochester quadrajet 4mc is a 4 bbl carb with electronic Mixture Control and was used many years in the late 80's and early 90's until fuel injection became more popular
To adjust the fuel-air mixture on a four-barrel Rochester Quadrajet, first ensure the engine is at operating temperature. Use a vacuum gauge to measure manifold vacuum and adjust the idle mixture screws, typically located at the front of the carburetor, to achieve the highest stable vacuum reading. Additionally, check the float level to ensure it’s set correctly, as this affects the fuel delivery. Finally, for performance tuning, you may consider adjusting the secondary air flap tension or swapping jets as needed.
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
A good default setting is 1.5 turns. After that you can continue to turn them out with a rpm gauge connected. Then gauge needs to be accurate. Some timing lights will show rpm. Turn each one out separately until max rpm is reached. Ideally a exhaust gas analyzer is best to use as it will take into effect engine wear.
To adjust the idle on a 2-barrel Rochester carburetor, first ensure the engine is warm and idling. Locate the idle mixture screws on either side of the carburetor; turning them clockwise enriches the mixture, while counterclockwise leans it out. Adjust each screw slowly, listening for the smoothest idle and optimal RPM. Finally, set the idle speed using the throttle stop screw to achieve the desired idle RPM.
The only setting is one screw on the top of each carb its the mixture screw and should is 1.5 turns out by default.
Too much air to fuel mixture with your carburetor, adjust the carb settings to allow for more fuel to enter the chambers.
The air adjustment screw on a Bearcat 454 carburetor is typically located on the side of the carburetor body, near the throttle linkage. This screw is used to fine-tune the air-fuel mixture for optimal performance. Turning it clockwise generally enriches the mixture, while counterclockwise leans it out. Always refer to the specific manual for your model for precise adjustments and settings.
Needing more info for a complete answerChevy didnt build a Tahoe in 1986. If you are refering to the full size Blazer K5 or K10, the carb would likely be a Rochester Quadrajet with computer feedback/emissions solenoids. it really doesn't matter what vehicle the carb is on the correct air fuel mixture is 14:1. 14parts air to 1part fuel. also Chevy built a s-10 with a Tahoe package in 86
To fix an improper gas-air mixture, you may need to adjust the carburetor settings on the engine. This can involve tweaking the air-fuel ratio or adjusting the idle speed screw. If the issue persists, it may be necessary to clean or replace the carburetor components to ensure proper fuel delivery.