The Carter Thermo-Quad carburetor is a special design used to keep the fuel cooler inside the carburetor, providing better fuel mileage. Adjusting the idle mixture screws on the Thermo-Quad takes only few minutes and provides better engine performance. The two adjustment screws are located on the front of the carburetor, giving you easy access. Adjustments may be made with common household tools.
Remove the vacuum hose from the EGR valve and place a plug inside the end of the hose to close it off. Attach a jumper wire from the vehicle frame to the carburetor switch to ground the switch.
Detach the canister hose and place a plug in the end of the hose. Disconnect the PCV valve from the intake manifold valve cover and set it aside.
Remove the rubber vacuum hose from the base of the carburetor and attach a vacuum gauge to the vacuum port on the carburetor. Start the motor and let it warm up for a few minutes.
Remove the engine harness connector from the oxygen sensor on the carburetor and ground the harness lead wire by attaching it to a jumper wire. Keep the motor running for another four minutes to allow the carburetor to stabilize.
Turn the the two idle mixture adjustment screws in the front of the carburetor clockwise a quarter turn at a time with a screwdriver. Alternating between both screws until you hear the carburetor smooth out and both adjustment screws are giving the same reading on the vacuum gauge.
Shut the engine off and remove the vacuum gauge from the carburetor base. Reattach the vacuum hose, PCV valve, canister hose and EGR valve hose.
Remove the jumper wires and reattach the engine harness connector.
