DeSoto Carburetors for old Desoto's : DESOTO MODEL S10 1942

Form 6496—Canadian
DE SOTO—EFI
April, 1942
Reprinted April, 1944
CAR SERIAL NUMBER 9-949-05I and higher
MOTOR SERIAL NUMBER
S 10- 100 l and higher
EFI used on cars with fluid drive and
standard transmission.
The above carbureter is also used on
Chrysler "C34" cars for 1942.
B-B DOWN-DRAFT CARBURETER—MODEL EF1, $30.85
A $5.00 exchange allowance is deducted from the list price if buyer turns in the carbureter which is replaced by an EFI.
CARBURETER SPECIFICATIONS

DESOTO MODEL S10 1942

For DeSoto Six Cylinder Engine:
Dimensions: Flange size, III// inch (38.1 mm). Throttle bore, I-I I/16 inch (42.86 mm).
Main venturi, I-11/32 inch (34.13 mm) I. D.
Float Setting: Top of float 1/16 inch (1.58 mm) below top surface of carbureter body casting. (Plus or minus 1/64 inch (.397 mm).
Vents: Outside, none. Inside balance vent .218 inch diameter (5.54 mm).
Gasoline Intake Needle: Triangular, horizontal, No. 44 (2.18 mm) drill in needle seat.
Idle Orifice Tube: Jet size, .0276 inch (.70 mm) drill. Idle passage air bleed (in body) size .063 inch (1.60 diameter.
Economizer in body—size .053 inch (1.35 mm) diameter.
Idle Ports: Upper port. Keyhole type; length, .128 inch (3.25 mm); width, .027 inch (.69 mm); .063 inch (1.60 mm) diameter hole at top.
Top of port located .088 to .092 (2.24 to 2.34 mm) above top edge of valve.
Lower port size, .053 to .057 inch (1.35 to 1.45 mm) drill. (for idle adjustment screw.)
Set Idle Adjustment Screw: 1/2 to 11/2 turns open. For richer mixture turn screw out. Do not idle engine below 300 r.p.m. or 6 miles per hour. -
FOR READINGS BELOW, VIEW CARBURETER WITH
Throttle Lever: Adjusting—on left side.
Slow Closing Throttle: (EFI) Dash pot with discharge ,(by-pass), size .0197 (.5 mm) drill, through plunger shaft.
3-7/16 Inch Bore, 41/4 Inch Stroke
Main Metering Screw: Calibrated to flow 312 to 316 cc per minute. (Do not gauge for size. If in doubt, replace with new part.)
Main Vent: Through diffuser (air bleed inside bowl), size .0315 inch (.80 mm) drill.
Main Vent Tube:
Side holes:
2—.0354 inch (.90 mm), 21/64 inch (8.33 mm) from end. 2—.0354 inch (.90 mm), I-1/64 inch (25.8 mm) from end.
Step-Up Jet: Size, .0413 inch (1.05 mm) drill.
Accelerating Pump: Type, delayed action. Stroke: Summer setting (inner hole, short stroke).
Intermediate setting (center hole).
Winter setting (outer hole, long stroke).
Pump intake passage, size .115 to .120 inch (2.93 to 3.05 mm) diameter in body. Pump discharge passage: restriction (under ball check), size .062 to .065 inch (1.57 to 1.65 mm) diameter in body. Pump (discharge) jet size .0374 inch (.95 mm) drill.
Pump Adjustment: 13/32 inch plunger travel; full throttle position, medium stroke. Use gauge T109-I17S.
Vacuum Spark Port: Slot (round end) type. Size .040 by .110 inch (1.016 by 2.794 mm). Top of port .035 to .041 inch (.89 to 1.04 mm) above top edge of valve.
FLANGE DOWN AND FLOAT CHAMBER AT RIGHT
Choker: Butterfly type, with compensating (poppet) air valve. Throttle and Choke Valves: Interconnected to open throttle valve to fast idle position when choke is in use.
mm)
Motor Tune-Up--Be Accurate! Always Use Feeler Gauges!
CAUTION: Change worn or leaky flange gaskets. Tighten manifold bolts and test compression before adjusting carbureter.
Spark Plug Gap .025"
Set
Breaker Points
.020"
Use Motor Gauge
Breaker Points to Open:
Top Dead Center
VALVE CLEARANCE
Set Valves (Hot) Intake .008" Exhaust .010"
Idle Adjustment Screw Setting
1/2 to 11/2
Turns Open
CARBURETER ADJUSTMENTS
If carbureter loads up after considerable service, check float level. Wear on lip of float lever will raise float level. Before adjusting float, be sure float lever pin is firmly seated. Reset float level by bending lip of float lever away from needle to raise level, or bend lip toward needle to lower float level. Bend vertical lip of float only.
If motor stalls while idling, set throttle lever adjusting screw so motor runs approximately 300 r. p. m. Then set idle adjustment screw to specifications. If these adjustments do not correct the trouble, remove idle orifice tube and plug assembly. Clean tube and passages with compressed air.
If acceleration is not satisfactory remove pump jet and clean with compressed air. However, it is usually advisable to replace the pump jet, as its cost is nominal. All jets must be seated gasoline tight. Poor acceleration may be due to damaged or worn plunger leather in accelerating pump.sediment in pump cylinder or clogged intake ball check at bottom of pump cylinder and discharge ball check in discharge passage. If 'plunger is removed from cylinder, use care in installing to avoid damage to plunger leather.
Correct air fuel ratio is provided by a "balance tube" cast in the air horn. The balance tube should be checked each time the carbureter is serviced to see that the passage is open. The object of a balanced carbureter is to provide a constant air fuel ratio regardless of type, size or condition of air cleaner. Should the cleaner become clogged, the capacity will be reduced but the air-fuel mixture ratio will not be changed.
Excessive richness above 50 miles per hour may be caxsed by a clogged main vent tube. After removal of rivet plug beneath float bowl with tool No. T109-42, main vent tube can