How to adjust the carburetor on a 1969 AMC AMX?

Experiencing issues with your 1969 AMC AMX carburetor can lead to a variety of performance problems, such as rough idling, stalling, or poor acceleration. These symptoms are often indicators that your carburetor needs adjustment to ensure optimal fuel-air mixture and engine performance. Here is how to solve this issue:

Step 1: Gather Your Tools

Before you begin, make sure you have the necessary tools ready:

• A flat-head screwdriver
• A Phillips-head screwdriver
• A tachometer (optional)
• A vacuum gauge (optional)

Step 2: Locate the Carburetor

The carburetor is typically found on the top-middle section of the engine. It’s an assembly that has various linkages and is connected to the air filter housing. If you follow the air intake system, it will lead you directly to the carburetor.

Step 3: Remove the Air Filter Housing

To access the carburetor, you'll need to first remove the air filter housing. This can generally be done by unscrewing the wing nuts located on top of the housing. Once unscrewed, lift the housing off the carburetor and set it aside.

Step 4: Identify the Adjustment Screws

On your 1969 AMC AMX carburetor, there are usually two key screws that require adjustment:

• The Idle Mixture Screws: These are typically found on the front base of the carburetor, often on either side. They control the air-fuel mixture at idle.
• The Idle Speed Screw: This is usually located on the linkage and adjusts the engine’s idle speed.

Step 5: Adjust the Idle Mixture Screws

1. Initial Adjustment: With the engine off, use the flat-head screwdriver to turn both idle mixture screws clockwise until they gently seat. Do not over-tighten them. Then, turn each screw counterclockwise about 1.5 turns to start.
2. Fine-Tuning: Start the engine and let it warm up to normal operating temperature. Using the flat-head screwdriver, turn the idle mixture screws slowly in or out until you achieve the highest idle speed. Ideally, you'll use a tachometer to find the highest RPM.

Step 6: Adjust the Idle Speed Screw

1. Initial Warm-Up: Let the engine warm up completely.
2. Adjusting: Using the Phillips-head screwdriver, locate the idle speed screw on the throttle linkage. Turn the screw to either increase or decrease the idle speed to your vehicle’s recommended RPM specifications, which can usually be found in the owner's manual or a service manual.

Step 7: Re-check and Fine-Tune

After making the initial adjustments, re-check both the idle mixture and idle speed screws. These settings often interact, so you may need to go back and forth a few times to get the optimum performance.

Step 8: Reassemble and Test Drive

Once you're satisfied with the adjustments, reassemble the air filter housing by placing it back over the carburetor and screwing the wing nuts back in place. Take your AMC AMX for a test drive to ensure that the performance issues have been resolved.

By carefully following these steps, you should be able to adjust the carburetor on your 1969 AMC AMX, leading to improved performance and a smoother driving experience.