From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Service bulletin for the 1937 Buick Stromberg 'AA' Carburetor, detailing adjustments and system operations.
| Identifier | ExFiles\Box 122\2\ scan0249 | |
| Date | 1st October 1936 | |
| BUICK 1937 ALL SERIES Page 4 STROMBERG CARBURETOR SERVICE BULLETIN BENDIX PRODUCTS CORPORATION STROMBERG CARBURETOR DIVISION SERVICE BULLETIN STROMBERG “AA{D. Abbot-Anderson}” CARBURETOR 1937 BUICK All Series STROMBERG CARBURETOR Model AA{D. Abbot-Anderson}-1 No. A-18361 for Series "40" Buick Symbol No. 1298605 Model AA{D. Abbot-Anderson}-2 No. A-18362 for Series 60, 80, 90 Buick Symbol No. 1298607 GENERAL DESCRIPTION The Stromberg Model “AA{D. Abbot-Anderson}-1” used on Buick Series 40 and the “AA{D. Abbot-Anderson}-2” carburetor used on Series 60-80-90 are duplex downdraft type especially adapted to the 1937 Buick cars. The principle of operation is the plain tube using air-bled jet to maintain the proper mixture throughout the entire range. The carburetors are of aircraft design. The fuel chamber completely surrounds the entire body; this feature enables the fuel to be maintained at the proper level under varying operating conditions. Another feature in the float chamber design are the baffles which help to control surging of the fuel on sharp, sudden turns. The float needle valve is hooked to the float lever which makes it positive acting at all times. A removable plug for checking the position of the fuel level is provided in the float chamber. These models are really two carburetors built into one. There is a set of venturi tubes, a main metering jet, an idle system with an adjustable needle, throttle valve, and a pump discharge nozzle for each barrel. Both barrels are supplied fuel by one float chamber. There is only one air inlet. The idling system supplies all the fuel at idling speeds and also on part throttle up to approximately 22 M.P.H. From approximately 22 M.P.H. to 75 M.P.H. part throttle, all of the fuel is supplied through the main metering system. The additional fuel necessary for speeds above 75 M.P.H. and on all wide open throttle operation is supplied through the economizer valve. An accelerating pump is connected directly to the throttle; this together with the economizer assures proper operation under all conditions. Accelerator Switch Adjustment SWITCH ADJUSTMENT (Model 1607) All Series. Rotate COLD IDLE CONTROL CAM around by hand until it strikes top. This is the fast or cold idle position. Leave the cam in this position until the switch has been adjusted. Disconnect switch operating rod at (C) and turn rod until line on switch lever comes exactly opposite FAST IDLE LINE on switch back when rod is directly opposite hole. Check alignment of marks after replacing rod, as this adjustment must be accurate. Accelerator Pedal Adjustment ACCELERATOR PEDAL ADJUSTMENT After the engine idle has been adjusted, the accelerator pedal angle should also be checked. This is done by depressing the pedal until the stop strikes the floor mat then setting adjustment trunnion “B” on the rod connecting to the accelerator until the throttle is wide open. MAIN METERING SYSTEM Fuel enters the carburetor at gasoline inlet through the float needle valve (18) and (19) and into the float bowl where it is maintained at constant level by floats (14). See illustrations. Air enters the carburetor through air inlet and places suction on the main discharge jet (2) or idle discharge holes (10) depending on the amount of throttle opening. The main metering jets (5) are of the fixed type. They control the flow of gas during the intermediate or part throttle position up to approximately 75 M.P.H. From the metering jet the fuel passes into the main discharge jet (2) where it is mixed with air from high speed bleeder (3) and flows into the carburetor barrel down to the intake manifold. All jets of the fixed type are calibrated at the factory to supply the correct mixture for normal operating conditions and should not be changed without special instructions from the factory. NOTE: When servicing carburetor, and the main discharge jets are removed, the lead gasket (7) must be replaced by a new one to assure a good seal when the main jet is reassembled. NOTE: A new type of main metering jet is used in these carburetors to distinguish it from jets of similar design a groove has been added on the shank of the jet. The part number is P-22660 and should not be interchanged with other jets. For AA{D. Abbot-Anderson}-1 on the Series “40” cars P-22660 size .049” is used with the standard air cleaner; size .045” to be used with oil bath type of heavy duty cleaner. For AA{D. Abbot-Anderson}-2 on Series 60-80-90 cars P-22660 size .052” is used with a standard air cleaner and .051” for oil bath type cleaner. T-24924 Wrench is used for assembling of jet. IDLE METERING AND ADJUSTMENT Fuel for idle speeds is taken through the idle tube (4) where it is mixed with air from the air bleeder at the top of the idle tube. The mixture passes to the idle channel where additional air is mixed with it through the secondary idle air bleeder (8). It is then discharged through the idle holes (10). On “curb idle” or closed throttle, fuel is drawn only from the lower idle discharge hole due to the high suction at this point. As the throttle is opened, suction is also placed on the upper idle discharge hole to feed additional fuel until the throttle is opened to the position where the main discharge jet comes into operation. When adjusting the idle needle valves, have the engine well warmed up so that the intake manifold is warm to the hand, and the throttle stop screw is on slow idle. The idle speed of the engine should be set at a speed equivalent to 7 to 8 M.P.H. by adjusting stop screw (39). The idle needle valves (9) control the fuel for low speed adjustment. Turning OUT the needle gives a richer mixture and turning IN a leaner mixture. Taking one barrel at a time, turn the idle adjustment IN slowly until the engine begins to “lag” or run irregular, then slowly turn OUT until the engine begins to “roll”. Finally, very slowly, turn in the adjustment again, just enough so that the engine runs smoothly for this throttle opening. Set the mixture to one set of four cylinders. Do the same with the other idle needle valve. It may be necessary, after making adjustments, to cut down the engine speed slightly. Diagram Key: 1. Choke Valve. 2. Main Discharge Jet. 3. High Speed Bleeder. 4. Idle Tube. 5. Main Metering Jet. 6. Main Discharge Jet Plug. 7. Main Discharge Jet Gasket. 8. Idle Air Bleeder. 9. Idle Needle Valve. 10. Idle Discharge Holes. 11. Throttle Valve. 12. Primary Venturi. 13. Auxiliary Venturi. BENDIX PRODUCTS CORPORATION STROMBERG CARBURETOR DIVISION (Service Stations All Over the World) 401 BENDIX DRIVE SOUTH BEND, INDIANA Form No. 10-135-5M-10-36-SPI Printed in United States of America | ||