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CARBURETOR REPAIR - PAGE 4-11
If excessive engine "stumbling" or hesitation is
encountered at speeds of 15 to 17 MPH, on 6 cylin-
der engines with the old type carburetor (Vendor tag
No. 647S) and having the new style distributor with
the revised spark advance (No. IGS-4213A-1 on
distributor name plate).
We recommend that the old type metering rods
Carter No. 75-610 and the old type idle by-pass
plugs Carter No. 11B-167 be replaced with the new
type metering rods Carter No. 75-686 and idle by-
pass plugs Carter No. 11B-159. This change can
easily be made as follows:
1. Raise hood and install fender covers.
2. Remove air cleaner.
3. Remove carburetor dust cover screws and dust
cover.
4. Remove air horn attaching screws and remove
air horn with all parts attached.
NOTE: The screw inside the carburetor air horn
must be removed.
5. Remove old metering rods and install new me-
tering rods. Use a small pair of long-nose pliers
to hook up the metering rod spring.
6. Remove idle bleed jets and install new jets.
7. Install air horn (make sure gasket is positioned
properly).
8. Install dust cover.
9. Install air cleaner.
10. Start engine and adjust carburetor (use vacuum
gauge).
The parts necessary to make this change-over can
be procured through the parts department under Part
No. 302838 Carburetor Metering Rod and By-Pass
Plug Kit.
NOTE: The new type metering rods and idle
by-pass plugs were released for production for
all 6 cylinder engines of the 490 series about
July 1, 1949. This change was made to com-
pensate for a lean mixture resulting from
mounting the carburetor in a vertical position
and the revision of the distributor automatic
advance curve. Carburetors with the new style
jets can be identified by the part number (647SA)
on the metal tag attached to the carburetor.
CARBURETOR - PAGE 4-13
Paragraph 10 should read: Install check valve and
pump discharge valve retainer plug. Figure 29
should show a triangular valve having a conical end.
FUEL PUMP - PAGE 4-17
Carter fuel pumps were used in the 490 series on
both 6 and 8 cylinder engines replacing the A.C.
standard fuel pump. This change became effective
after August 26, 1949. The Carter fuel pumps can be
identified by the Part No. M-729-SZ located on the
side of the mounting flange.
For repair procedures refer to your 500 Series
Mechanical Procedure Manual.
The following list covers the A.C. Fuel Pumps and
the Carter Fuel Pump:
FAC-
TORY
REPAIR DIAPHRAGM KIT
NO.
SERIES
1539109
AH
R-14
1539108
AJ
R-139
M729SZ
VACUUM BOOSTER TEST - PAGE 4-23
Paragraphs 2, 3 and 4 should read:
2. Connect the KMO-144 or equivalent vacuum
gauge to the inlet port and disconnect outlet.
3. Gauge should show 8-1/2" of mercury at 120
RPM and 12" at 1800 RPM.
4. If vacuum is less than 7 inches, repair or replace
the pump.
GAUGE TROUBLE SHOOTING - PAGE 4-24
Paragraph 1B is in error. The condenser at the gas
tank gauge unit was not used on 480-490 series cars
equipped with radio.
KIT
FUEL
VACUUM
D-18
D-65
D-28
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