DeSoto Carburetors for old Desoto's : DESOTO MODEL SD LATE 1933

Form No. 610IC—Canadian
DE SOTO E6A3-E6A4 Issued September, 1933 Reprinted February,1945
CAR SERIAL NUMBERS E6A3—9602675 and higher E6A4—9602995 and higher
MOTOR SERIAL NUMBERS E6A3—SDI 1788 and higher E6A4—SDI 2346 and higher

DESOTO MODEL SD LATE 1933

Superseded by E6P3
DOWN-DRAFT CARBURETERS, MODELS E6A3-E6A4--LIST PRICE $29.40
A $5.00 exchange allowance is deducted from the list price if buyer turns in old carbureter.
CARBURETER SPECIFICATIONS
For De Soto 6-Cylinder Engine: Bore, 3¼ Inches
Dimensions: Flange size, 11/2 inch (38.10 mm). Throttle bore, I-11/16 inch (42.86 mm). Main venturi, 11/4 inch (31.75 mm) I. D.
Float Setting: Top of float 5/64 inch (1.98 mm) below top of surface of carburetor body casting. (Plus or minus) 1/64 inch (.397 mm).
Vent: (To float chamber) outside. Size, 3/16 inch (4.76 mm). Gasoline Intake Needle: Triangular, Horizontal. No. 42 (2.38 mm) drill in needle seat.
Idle Orifice Tube: Jet size, .0276 inch (.70 mm).
Idle passage air bleed (through plug) size. .061 to .063 inch (1.55—1.60 mm).
Idle Ports: Upper Port size, .062 inch to .064 inch (1.58 to 1.63 mm) diameter.
Bottom of port located .004 to .008 inch (.10 to .20 mm) above top edge of valve.
Lower port size, .053 to .057 inch (1.35 to 1.45 mm) diameter. (For idle adjustment screw.)
Set Idle Adjustment Screw: 5/8 to 11/4 turns open. For richer mixture turn screw out. Do not idle engine below 300 rpm. or 6 miles per hour.
Main Metering Screw: (E6A3) Calibrated to flow 266 to 270 cc per minute. (E6A4) Calibrated to flow 252 to 256 cc per minute. (Do not gauge for size. If in doubt, replace with
(82.55 mm); Stroke, 4% Inches (111.13 mm).
new part.)
Vent Tube: Air bleed through plug in diffuser, size, .0315 inch (.80 mm) drill.
Accelerating Jets:
2—.0354 inch (.90 mm) 21/64 inch (8.33 mm) from end. 2—.0354 inch (.90 mm) I-I/64 inch (25.8 mm) from end.
Step-Up Jet: (Power Orifice) size, .0315 inch (.80 mm) drill.
Accelerating Pump: Type, delayed action.
Stroke, (E6A3) Summer setting (inner hole, short stroke) 5/16 inch (7.94 mm).
(E6A4) Summer setting (inner hole, short stroke) 21/64 inch (8.33 mm}.
(E6A3) Intermediate setting (center hole) 15/32 inch (11.91 mm).
(E6A4) Intermediate setting (center hole) 7/16 inch (11.11 mm).
(E6A3) Winter setting (outer hole, long stroke) % inch (15.87 mm).
(E6A4) Winter setting (outer hole, long stroke) 35/64 inch (13.90 mm).
Pump intake passage, size 1/8 inch (3.18 mm).
Pump needle seat size, No. 52 (1.61 mm) drill.
Pump (discharge) jet size, .0354 (.90 mm) drill.
Choke: Manual—Butterfly type, with pressure relief poppet valve.
MOTOR TUNE-UP—Be Accurate! Always Use Feeler Gauges!
CAUTION: Change worn or leaky flange gaskets. Tighten manifold bolts and test compression before adjusting carburetor. Use Gauge
Type of Ignition Setting
Distributor (Piston Travel)
f Small .033" Before T. D. C.
1 Large Exact T. D. C.
I Small .020" Before T. D. C.
1 Large .015" Past T. D. C. Intake' .005"
Small .020" Before T. D. C.
Large .020" Past T. D. C. Exhaust .007"
CARBURETER ADJUSTMENTS
Spark Set
Plug Gap Breaker Points .025"
Type of Cylinder Head
Silver Dome Red Head
6 to 1 Ratio .020" (Painted Silver)
Use Motor Gauge
Points Open
WHEN MOTOR IS ILA AT OPERATING
TEMPERATURE i
VALVE CLEARANCE
0
C7- e
r __Lee ,et-_e7 Flush with to
1/16" below edge ( Remove Gasket)
of Casting Turns Open
Idle Adjustment
Screw Setting
% to I I/4
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 plug Is firmly seated. Reset float level by bending lip of float lever away from needle to raise level, or bending 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 rpm. Then set idle adjustment screw as instructed above. If these adjustments do not correct the trouble, remove idle orifice tube and plug assembly and clean with compressed air.
If acceleration is not satisfactory remove pump jet and clean with compressed air. Also examine pump link setting. Pump link has three holes giving short, medium and long strokes. If link is set to short stroke, reset to give longer stroke to pump piston. In hot weather, high altitudes, or when high test gasoline is used, connect pump link in inner hole, giving shorter stroke.
Maximum economy is secured only when breaker points, spark plugs, valves and motor timing are set to manufacturer's specifications. After motor is properly tuned, the following should also be dune to insure satisfactory performance and economy:
(a) Float level must be set as above.
(b) Bail check in step-up valve assembly must seat and move freely. When reassembling, valve housing must be screwed in tight against seat.
(c) Step-up push rod must move freely in upper and lower guides.
(d) Step-up piston in upper casting should not bind and must be free from dirt.
(e) Main metering screw can be replaced with leaner than standard metering screws, for altitude or high test fuel.
Caution: Do not attempt to gauge metering jets with drills. These jets have been flow-tested, to insure correct fuel flow.