DISASSEMBLY, REPAIR,
REASSEMBLY INSTRUCTIONS
WALBRO CARBURETOR OPERATION
Alternate fuel pump system
to
accom-
modate internal pulse and/or external fuel
source.
1.
Engine Impulse: Actuates Fuel Pump Diaphragm with
13.
Idle take-Off: Fuel entry for Idle holes.
alternating pressure-vacuum pulses.
14.
Idle Port: Fuel reservoir for Idle holes.
2.
Fuel Pump Diaphragm: Fluctuates
in
response to engine
impulse. Transfers fuel through Fuel Pump Valves.
15.
Atmospheric Vent: Allows air pressure against Metering
Diaphragm.
3.
Fuel Inlet: Fuel drawn from tank.
4.
Inlet Valve: Responds to Fuel Pump Diaphgram. Opens
during vacuum pulse. Closes during pressure pulse.
5.
Outlet Valve: Closes during vacuum pulse. Opens during
pressure pulse.
6.
Filter Screen: Filters fuel on route to Metering Chamber.
7.
Inlet Needle Valve: Lifts off seat to allow fuel entry into
Metering Chamber.
8.
Throttle Valve: Regulates engine speed
as
it
exposes Pri-
mary. Second, and Third Idle holes, then Nozzle for fuel
delivery.
9.
Primary Idle Hole: Only fuel source to engine at Idle
position.
10.
Second Idle Hole: Allows additional fuel flow on accelera-
tion.
16.
Circuit Plate: Meters fuel from Metering Chamber to Low
Speed and High Speed Circuits.
Metering Lever.
17.
Metering Diaphragm: Drawn up by vacuum to activate
18.
Metering Lever: Lifts Inlet Needle
off
seat.
19.
Metering Lever Spring: Transmits force to Metering Lever.
Closes
Needle Valve as Metering Chamber fills.
20.
Metering Chamber: Fuel reservoir, feeds to Idle and Nozzle
circuits.
21.
Nozzle Check Valve: Engine vacuum draws Valve open.
22,
Nozzle Well: Fuel is drawn
in
from Metering Chamber at
high speed
23.
Hi Speed Needle: Adjusts for fuel richness at high speeds.
24.
Nozzle Increases fuel discharge for high speeds.
11.
Third Idle Hole: Increases fuel flow at Part Throttle.
12.
Idle Needle: Adjust for fuel richness to
3
Idle holes.
25.
Venturi: Increases air velocity at Nozzle, creating a suction
to draw fuel into Throttle Bore.
13
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