Holley 2110 Main Metering

Main Metering System Operation

The Main Metering System in the Holley Model 2110 carburetor is responsible for delivering the proper fuel-air mixture during normal cruising and higher-speed engine operations. It begins functioning once the air velocity through the venturis becomes strong enough to create a significant pressure differential.

Core Process

• Pressure Differential: As the engine runs, the intake stroke of the pistons draws air through the carburetor venturi and booster venturi. The air passing through these restricted areas creates a low pressure (vacuum).

• Fuel Flow: The difference between the low pressure in the venturi and the atmospheric pressure in the float chamber forces fuel to flow through the main jet and into the main well.

• Air Bleeding: As fuel moves up the main well, it passes the main well air bleed, where air is added to the raw fuel. The amount of air added increases proportionally with engine speed.

• Vaporization: This lighter mixture of fuel and air responds more quickly to pressure changes and vaporizes more readily than raw fuel when it is finally discharged.

  Discharge: The fuel-air mixture travels through a horizontal channel and is released through the discharge nozzle into the booster venturi, where it joins the primary air stream.

Control and Distribution

• Engine Regulation: The throttle plates regulate the total amount of this mixture allowed into the intake manifold, thereby controlling the speed and power output of the engine based on accelerator pedal movement.

• Anti-Percolation: The design of the booster venturi nozzle bars features a large main well with a long vertical rise. This design helps minimize "percolation" (fuel boiling on hot days) by allowing vapor bubbles to break before they can carry raw liquid fuel into the discharge nozzle.

Component Summary