carburetor parts and funtions

1. í-
Carburetor Systems

2. The Float Bowl
Fuel inlet system
Stores fuel for
immediate use
Maintains level
FLOAT ACTION
ACT1VATES VALVE
T
• Viton Needle, brass
Seat
• Dampening spring
• Vapors vented to
carbón canister
NEEDLE
VALVE
FROM
FUEL
PüMP

3. Idle Circuit
• Low airflow @ idle,
main system will not
opérate
• High vacuum under
throttie píate draws
fuel out idle ports
• Sometimes adjustable
• Idle air bleed helps
atomize fuel

4. Transfer Circuit
• Adds fuel as throttie píate opens, overcomes “lag

5. 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

6. Power Circuit
• Provides extra
fuel at WOT
• Mechanical
power val ve,
maybe adjustable
• Sometí mes
combination with
meten ng rods
• Flows through a
Circuit into main
metering system
MECHANICAL
POWER ENRICHMENT
SYSTEM
" TOTHROTTLE
LINKAGE
METEHING
ROD
MAIN
METERING
JET

7. Accelerator Pump
THROmE
LIKKAGE
ACCELERATOR
PUWP
PISTON
During sudden
acceleration,
mixture leans out
Pumps a lot of
fuel inte venturi
CHECK
BALL&
WEIGHT
L

8. Choke Circuit
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3TAJq 3)(0HQ
• Very rich A/F needed
on coid starts
• Gloses off top of
venturi to raise the
vacuum level
allowing greater fuel
flow into manifoid
• Opens as engine
warms up, or as an
electric coil heats up

9. Choke Coil Operation
MOVEMENT
OF COIL END
MOVEMENT
OF COIL END
ANCHOR
ANCHOR
COLD
HEAT

10. Choke Pulloff
• Forces the choke open
slightiy just after
engine starts.
• Position determined by
- torque of coil
- air velocity on blade
- vacuum on pistón
- musí adjust correctly!

11. Altitude Compensator
• Compensates for altitude
• Adjusts an air bleed

12. Idle Speed Control
.SPRINQ
ELECTRICAL
CIRCUIT
THROTTLE
LEVER ELECTRÍC
SWITCH
MOUNTING BRACKET

13. Throttie Kicker
1. Dashpot, 2* Throttie kicker, 3. Throttie cable, 4. Idle adjustment
Electric motor or solenoid, increases idle