To change a carburetor, disconnect the car battery, unhook the fuel lines and the throttle linkage, remove the carburetor, replace the gasket and install the new unit. The process, bolt locations and other vehicle accessories that may need to be removed to access the carburetor can vary depending on the car's make, model and year.
Take a picture of the carburetor before disconnecting any of the lines so you have a reference guide for the re-installation. Remove the negative cable from the battery terminal. Disconnect the fuel lines, and move them to the side, keeping the ends elevated to avoid spilling excess gasoline. If your vehicle is an automatic transmission, you must remove the throttle linkage as well.
Remove the flange bolts that secure the base of the carburetor to the intake. Keep the carburetor level when you lift it from the intake to avoid spilling the fuel remaining inside it. Stuff clean shop towels into the open intakes to avoid foreign material from falling inside while the carburetor is not in place.
Clean the gasket mounting surface on the intake face thoroughly. Remove the rags from the intake, and mount the new gasket. Bolt the new carburetor in place, and reattach the fuel lines and throttle linkage. Clean up any spilled fuel before connecting the battery.