The Importance Of Tuning A Carburetor

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If you own a muscle car like [a Super Sport Nova] or even a vintage [Triumph British Sports car] it has a carburetor. This article will help you learn how to adjust it for maximum efficiency. We'll cover where to start and what additional tools can help you apply some precision to the operation.

Mechanics consider these adjustments the icing on the cake. Meaning, it's the last task to perform after a tune-up or repair operation. As an example, ignition problems, setting the base timing, and repairing vacuum leaks must be performed prior to making final adjustments to the carburetor. First, let’s clear up what moving the mixture screws can accomplish.

What Can Carburetor Tuning Improve

Tuning a carburetor can improve operation and performance
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A classic car with a one barrel would have one screw and the two barrels have two. However, a four barrel carburetor will also have two mixture screws. The rear barrels are for secondary enrichment and only utilized under heavy acceleration.

A good place to start this operation is to know where the screws are now, before making any adjustments. Sometimes people like to mess around with the screws to the point where all logic has been abandoned. For this reason it's nice to know where they are now and where to start from. With the engine off slowly turn the screws in clockwise and count the amount of turns until they gently hit bottom. It's important not to crank down on the delicate screws.

When the mixture adjustment is all the way in, a needle point makes contact with a soft brass orifice. Over tightening the mixture screw can damage this hole of a predetermined size. When using a flat blade screwdriver it's easy to keep track of quarter and half turns. In the instance of a Phillips head adjustment screw you can make paint marks on the backside of the handle to keep track of these quarter and half
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This is a strong and reliable manifold vacuum source. Make adjustments with the engine at operating temperature. Adjust the base mixture screws to reach the highest vacuum and idle RPM readings. Both the engine idle RPM and vacuum should reach their apex at the same time.

After achieving this location use the final quarter turn to adjust for your personal preference. A quarter turn counterclockwise will richen the mixture. This provides a better transition from idle to part throttle and can eliminate hesitation. Turning the mixture screw a quarter turn in will lean the mixture and improve fuel economy and tailpipe emissions.

When Mixture Adjustments Don't Work

One major take away from this article is that mixture adjustments will only work on an automobile when everything else is operating perfectly. Although it can improve stalling, hesitation and rough idle problems caused by previous owners using improper procedures, it's not a substitute for [a complete carburetor overhaul].

Keep in mind that carburetor tuning is often done in conjunction with other small adjustments to solve specific problems. Other issues can generate similar complaints from drivers. As an example, if the base ignition timing is not correct it can also cause hesitation, stalling and rough
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