Question: What Is Main Metering Jet Size Carburetor Quizlet?

What is main metering jet?

A main metering orifice, or jet, is placed in the fuel passage between the float chamber and the discharge nozzle to limit the fuel flow when the throttle valve is wide open. It is this pressure difference, or metering force, that causes fuel to flow from the discharge nozzle.

What is the purpose of the main metering jet?

What is the function of a metering jet? The main metering jet is placed in the fuel passage between the float chamber and the discharge nozzle. Its purpose is to limit the fuel flow when the throttle valve is wide open.

How is the size of a metering jet check checked?

30. How is the size of a metering jet checked? Checked using a drill shank with the size of the shank labeled on the drill bit.

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What is the main metering system?

The main metering system supplies fuel to the engine at all speeds above idling. The fuel discharged by this system is determined by the drop in pressure in the venturi throat. A separate system is necessary for idling because the main metering system can be erratic at very low engine speeds.

Where is the main idling jet located?

In order to allow the engine to idle, a fuel passageway is incorporated to discharge fuel from an opening in the low pressure area near the edge of the throttle valve. [Figure 2-14] This opening is called the idling jet.

How do you check the accelerator pump in a carburetor if working properly?

Open the throttle quickly. You should see the accelerator pump system discharge a squirt of fuel into each primary barrel. The flow should continue for a few seconds after the throttle valve reaches the wide-open throttle position. If not, the accelerator pump system is defective.

How does an economizer work on a carburetor?

For an engine to develop maximum power at full throttle, the fuel mixture must be richer than for cruise. A typical economizer system consists of a needle valve which begins to open when the throttle valve reaches a predetermined point near the wide-open position.

What causes a single diaphragm accelerator pump to discharge fuel?

Which of the following causes a single diaphragm accelerator pump to discharge fuel? A) An increase in manifold pressure that occurs when the throttle valve is opened. An increase in venturi suction when the throttle valve is open.

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What happens if main jet is too big?

For example, using too large of a main jet will cause more fuel to enter the combustion chamber than it can efficiently burn. This will result in a “sputter” at full throttle. It could best be described as a rapid misfire.

What happens if main jet is too small?

Be careful: most engine jams occur when the main jet is too small. A lean fuel/air mixture will cause the engine to overheat fast.

What happens if main jet size is smaller?

Installing a smaller size jet will reduce fuel flow, which is ideal for high-altitude conditions where air is limited, where a larger jet size increases fuel flow for oxygen-rich, low altitudes.

What is used to control an automatic mixture control?

The automatic mixture control unit consists of a bellows assembly, calibrated needle, and seat. [Figure 2-27] The purpose of the automatic mixture control is to compensate for changes in air density due to temperature and altitude changes. This bellows responds to changes in pressure and temperature.

What is the difference between float type carburetor to pressure injection carburetor?

The basic difference between a float-type and a pressure-type carburetor is the delivery of fuel. The pressure-type carburetor delivers fuel under pressure by a fuel pump. The fuel-air mixture is then drawn through the intake manifold and into the combustion chambers where it is ignited.

Which type of carburetor has a float?

A type of carburetor used in reciprocating engines. In this carburetor, the fuelmetering force is produced by a float-operated needle valve that keeps the fuel level a constant distance below the edge of the discharge nozzle.

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