ROCHESTER CARBURETORS

Bulletin 9C-300 1 April 1953

INSTALLATION INSTRUCTIONS
1.   For 1932-1936 Replacement. (216 and 235 Cu. In. Engines, l-1/4" S.A.E. Flange). Remove old flange gas­ket. New asbestos flange gasket No. 839632 1/8" thick must be used between carburetor and engine manifold. Bend accelerator throttle rod at ends sufficiently before attaching to carburetor throttle lever to provide neces­sary clearance and to permit smooth operation and travel of carburetor throttle lever.
2.   For 1937-1952 Replacement. (216 and 235 Cu. In. Engines, l-1/4" S.A.E. Flange). Install new flange gasket No. 839632 1/8" thick on top of old heat insulator. This
3.
insures proper operation of vacuum operated power system.
For 1950-52 Replacement (235 Cu. In. Truck Engines with 1-1/2" S.A.E. flange). Moulded heat insulator No. 3692799 V2" thick must be used between carburetor and engine manifold. This insures proper operation of vacuum operated power system.
For 1950-1952 Replacement. (235 Cu. In. Powerglide Engines with 1-1/2" S.A.E. Flange). Moulded heat in­sulator No. 3692799 V2" thick must be used between carburetor and engine manifold. This insures proper operation of vacuum operated power system.
4.
tmp105-1.jpg
FLOAT LEVEL ADJUSTMENT
With air horn fully assembled, air horn gasket in position and assembly up-ended on a flat surface (Figure 1):
1.  Place float level gauge in position with gauge tang inserted in dis­charge nozzle.
2.   Bend float arms vertically so that each float just touches top portion of gauge.
3.   Carefully bend float arms hori­zontally so that each float is cen­tered in the gauge.
4.   Tilt assembly 90° each side and check that floats do not touch gauge.
tmp105-2.jpg
FIGURE 1
FIGURE 2
FLOAT DROP ADJUSTMENT                       As shown in Figure 2, with the air horn held right side up and floats suspended freely, bend the float tang at the rear of the float assembly so that the bottom of the float is 1-3/4" below the gasket surface.
tmp105-3.jpg
THROTTLE RETURN CHECK INSTRUCTIONS
1.   Completely assemble carburetor on engine manifold. Be certain accelerator pull back spring No. 3695705 is used.
2.   If necessary, bend the throttle return check bracket or throttle lever contact arm to center the adjusting screw on the radius of the contact arm.
3. Run the engine until it is warmed up.
4.   Adjust the throttle stop screw and idle adjusting needle to secure a smooth idle at 500 R.P.M. in "N" position.
5.   Shut off engine. Insert .090" feeler gauge between carburetor choke lever cam and fast idle lever. (Figure 3.)
6.  Using a 3/8" wrench turn the adjusting screw until it just contacts the throttle lever contact arm. Hold flats on shaft with wrench whenever adjusting screw is turned.
7.   Install air cleaner. Start engine and recheck idling adjustment.
Float level gauge M-250 is available from Borroughs Tool Company, Kalamazoo, Michigan
FIGURE 3
CARBURETOR SPECIFICATIONS
TUNE-UP SPECIFICATIONS
DIMENSIONS:
Primary Venturi—1-11/32" (.2350 cu. in. engines) 1-7/32" (216 cu. in. engines)
Secondary Venturi — 19/32" (235 cu. in. engines) 9/16" (216 cu. in. engines)
**lDLE DISCHARGE HOLES:
Idle Needle Orifice —.063 (1374, 2050, 3152, 3863, 3865), .067 {2051, 3060, 3160, 3864), .073 (4476, 3986, 4495), .081, (4475, 4477).
 

Year and Model

Spark Plug Gap

Breaker Point Gap

Ignition Timing

Idle R.P.M.

 
1932 All
.0?4"
.018"
12°
BTDC.
1933-34 All
.032"
.018"
10°
BTDC.
1935 Master and Truck
.032"
.018"
BTDC.
1935 Standard
.030-.035"
.018"
BTDC.
1936 All
.032-.035"
.018"
BTDC.
1937-46 Alt
.040'
.018"
BTDC.
450-500
1947-48 All
,040'
.018.024' New
Installation .015-022 Old
Points
BTDC.
450-500
1949-52 All
.035"
.018-.024" New Installation .015--022 Old Points

 

BTDC.
450-500*
IDENTIFICATION:
Main Metering Jet—Stamped with last two digits of Jet Part No.
Air Horn Gasket—Stamped with last 4 digits of Gasket Part No.
Second Idle Hole— .031 (2051, 3060, 3160, 3864,) .034 (1374, 2050, 3152, 3863), .040 (3986, 4476, 4495), .059, (4475, 4477).
Third Idle Hole—.028 (3986, 4476, 4495), .031 (1374, 2050, 3152, 3863, 3865), .036, (4475, 4477).
Fourth Idle Hole — .028 (1374, 2050, 3152, 3863, 3865).
Spark Hole —2 x .040 (all),
PUMP DISCHARGE HOLES:
.031 (235 cu. in. engines) .028 (216 cu. in. engines)
**POWER RESTRICTION:
.030 (1374), .038 (2050, 3152, 3863, 3865), .040 (2051, 3864), .041 (3060, 3160), .0375 (4475 4477), .046 (3986, 4495) .048 (4476).
**refers to carburetors which have these digits as the last four in its Part No. The first three digits of each carburetor number are 700.
*Powerglide idling R.P.M. should be 500 in "N"
A GENERAL MOTORS PRODUCT
tmp105-4.jpg
A UNITED MOTORS LINE

< PREVIOUS PAGE      NEXT PAGE>

 

RC INDEX

 

INFORMATION FOR 1960 and Earlier CHEVROLETS

 

WebCounter says that you are visitor number:

Please Report any Broken Links or Pages that do not load properly.  Webmaster

This Information is for Research and the Promotion of the Preservation of Older Chevys

All Names, Trademarks and Logos Belong to their Respective Owners.

 

Web Space Provided by TOCMP