GASOLINE
IDLE
ADJUSTMENT
Modification
Gas supply valve
Carburetor float
and needle valve
-
Choke
COMBINATION GAS-GASOLINE CAR-
BURETOR
This carburetor operates on either gasoline or gas-
eous fuels. To switch operating fuels, make ad-
justments according to Table
2.
The combination
carburetor consists of both the gasoline and gaseous
fuel carburetors on a single casting.
The com bi nzt ion g as-g asoline carb; retor ad justmen
t
is the same as for gasoline. See Figure
27
for location
of
the adjustment needles.
To Gasoline To Gaseous Fuel
Close
Open
Replace
if
Removc
if
for
removed for gas extendea operation
on
gas
-
reduces
wear
Remove lock Ins!all
lock
wire
wire
.
--
TABLE 2.
FUEL CHANGE CONVERSIONS
Spark plug gap
Gasoline fuel
supply valve
Set
at
.025â
Open Close
Set at
.025â
GASEOUS
FUEL
REGULATOR
The demand-type regulator opens upon a small
vacuum from the carburetor. It supplies .fuel on
demand, and shuts off fuel flow when the engine is
stopped, or when there is no demand.
The regulator
is
simply a diaphragm with linkage
connecting
it
to a valve in the gas line.
A
small vacuum
from the engine moves the diaphragm. opening the
delivery valve.
GAS
MAIN
ADJUSTMENT
.
REGULATOR
FIGURE
27.
COMBINATION CARBURETOR ADJUSTMENTS
26
BEGIN
SPEC.
R
Testing:
Blow into the diaphragm vent hole on the
regulator cover; this should open the valve.
An
audible hiss indicates that the regulator is opening.
A water manometer(Figure
28)
is the standard tool for
testing regulator inlet pressure, which must be within
the limits specified for your regulator. Use the chart
in
Figure
28
to convert the difference
in
water level
between the two tubes to pressure
in
ounces.
Gas Regulator (Algas):
The Algas regulator has no
adjustments, and features a positive lock-off if
pressure increases above the regglafcr setting. Max-
imum inlet pressure is
5
psi and minimum,
6
ounces.
The standard ONAN supplied solenoid shut-off valve
#307-0312,
locks
off
at a gas inlet pressure
of
slightly over one pound. An
optional valve
is
available with pressure rating to
5
psi.
See Figure
29.
Gas Regulator (Garretson):
The maximum allowable
inlet pressure is
8
ounces; minimum
2
ounces.
if
Gas
line pressure is greater than
8
ounces, install a
primary regulator to reduce the pressure. The
regulator has an adjustment to control the maximum
pressureatwhich the regulatorshutsoff when thereis
no demand. To obtain maximum regulatorsensitivity,
adjust it to just shut off at your line pressure when
there is no demand. Adjust the regulator for shut
otf
when there is no demand, to prevent gas leaks. The
factory adjusted shut-off is between
2
and
4
ounces. If
gas line pressure is between
4
and
8
ounces, readjust
the screw (Figure
30).
4
To adjust the
regulator, the gas line should be
connected and the outlet hose removed. Make a
coarse adjustment by turning the adjusting screw
Redistribution or publication of this document, î
by any means, is strictly prohibited.
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