How to Adjust your Carburetor

Adjusting your carburetor regularly is an important part of keeping your classic Nissan running. The carburetor is the main device used to determine the air and fuel mixture for your engine. With this quick guide, you can learn to adjust your own carburetor to prolong engine life and maintain optimum efficiency. 

Adjust the air and fuel ratio on your vehicle

First, make sure you remove your air cleaner to expose the carburetor underneath. Most often the air cleaner is held on with a wing nut and requires no tools. Once the carburetor is exposed, you should find two screws on the front of the unit which you will use to adjust you mixture. Most can be turned with a simple flat-head screwdriver. Important to note, if you’re looking to adjust a carburetor on a GM Quadrajet, you will need a special tool. 

Determine if your engine is running too rich or too lean

To determine if further adjustments are needed, start your engine and let it warm up. Once warm, bring up the RPMs and pay attention to how the engine behaves. What do you if your engine is pinging? Your mixture is probably too lean. Add fuel to the ratio. Does your exhaust smell like fuel? You’re most likely running a bit rich. It’s always easiest to lean your carb out by bringing both screws counter-clockwise slowly, and then moving them back to the rich side until optimum performance is achieved. 

You’re almost done! All that’s left is to replace your air cleaner assembly, perform a shakedown test drive, and enjoy the fruits of your labor. If you get stuck or need help getting it set just right, let our trusted technicians at Nalley Nissan Service Center help you out. 

Categories: Service