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Vacuum Vs. Mechanical Secondaries In Performance Carburetors

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The role of a carburetor is important in the performance of any vehicle's engine. A carburetor is responsible for managing airflow through the engine so that it can start and run efficiently.

Specialized throttle blades open and close within a carburetor in response to engine conditions. The primary throttle blades in all carburetors are activated by the throttle linkage. You can customize your carburetor to meet your needs by choosing between vacuum or mechanical activation for the secondary throttle blades.

The differences between these two activation methods can have a direct impact on the performance of your vehicle over time.

Vacuum-Activated Secondaries

Vacuum-activated secondaries rely on air velocity to open the throttle blades. Sufficient airflow must be supplied to the engine before vacuum-activated throttle blades are set in motion.

This approach to airflow management offers some unique benefits for drivers. The metered opening of the throttle blades can help you maintain high air velocity through the primary throttle blades when you are traveling at low speeds.

You can fine-tune the air velocity required to activate the secondary throttle blades in a vacuum-activated carburetor, giving you total control over the performance of your vehicles in the future.

Mechanical-Activated Secondaries

The manner in which secondary throttle blades are manipulated in a mechanical-activated carburetor is significantly different from the approach of a vacuum-activated carburetor. A secondary mechanical linkage is connected to the throttle linkage in a mechanical-activated carburetor.

Instead of relying on airflow to determine when secondary throttle blades should be opened, the activation of the secondaries is controlled by the primary throttle linkage instead. As soon as the primary linkage approaches the wide-open throttle setting, all of the secondaries are slammed open.

Mechanical-activated secondaries can limit your vehicle's performance when starting and accelerating quickly because of the limited airflow moving through the carburetor. You lose initial performance, but you gain greater consistency when driving long distances with a mechanical-activated carburetor.

If you are looking to customize your vehicle's performance and improve the efficiency of the vehicle's combustion engine, then you should consider swapping out the stock carburetor for a custom one. The type of carburetor in your vehicle can have a direct impact on engine longevity and performance.

Evaluate your driving and performance needs to determine whether a vacuum- or mechanical-activated secondary system would benefit you most as you invest in a new performance carburetor for your vehicle. Contact a local supplier for more information.