![Page 1: Carburetor Systems. The Float Bowl Fuel inlet system Stores fuel for immediate use Maintains level Viton Needle, brass seat Dampening spring Vapors vented](https://reader030.vdocuments.mx/reader030/viewer/2022032705/56649dbe5503460f94ab15be/html5/thumbnails/1.jpg)
Carburetor Systems
![Page 2: Carburetor Systems. The Float Bowl Fuel inlet system Stores fuel for immediate use Maintains level Viton Needle, brass seat Dampening spring Vapors vented](https://reader030.vdocuments.mx/reader030/viewer/2022032705/56649dbe5503460f94ab15be/html5/thumbnails/2.jpg)
The Float Bowl• Fuel inlet system• Stores fuel for
immediate use• Maintains level
• Viton Needle, brass seat
• Dampening spring• Vapors vented to
carbon canister
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Idle Circuit
• Low airflow @ idle, main system will not operate
• High vacuum under throttle plate draws fuel out idle ports
• Sometimes adjustable• Idle air bleed helps
atomize fuel
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Transfer Circuit
• Adds fuel as throttle plate opens, overcomes “lag”
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Main Metering Circuit
• Fuel supplied by “main jets”
• High venturi vacuum creates low pressure at nozzle tip
• Atmospheric pressure in float bowl pushes fuel out discharge nozzle
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Power Circuit• Provides extra
fuel at WOT• Mechanical
power valve, maybe adjustable
• Sometimes combination with metering rods
• Flows through a circuit into main metering system
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Accelerator Pump
• During sudden acceleration, mixture leans out
• Pumps a lot of fuel into venturi
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Choke Circuit
• Very rich A/F needed on cold starts
• Closes off top of venturi to raise the vacuum level allowing greater fuel flow into manifold
• Opens as engine warms up, or as an electric coil heats up
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Choke Coil Operation
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Choke Pulloff
• Forces the choke open slightly just after engine starts.
• Position determined by – torque of coil– air velocity on blade– vacuum on piston– must adjust correctly!
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Altitude Compensator
• Compensates for altitude• Adjusts an air bleed
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Idle Speed Control
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Throttle Kicker
• Electric motor or solenoid, increases idle
1. Dashpot, 2. Throttle kicker, 3. Throttle cable, 4. Idle adjustment