Carburetor Specifications (BMW 5 Series E12)

Design features of carburetors depending on the chassis number of the vehicle

"518"

Until May 1975, the Solex 38 PDSI carburettor with falling flow. Marking: copper-colored plate, identification N9 1 261 264 2. From May 1975 - two-chamber Solex 32/32 DIDTA carburettor, index E 17 386, emulsion type, with an automatic starting device of a mixed type, which uses a bimetallic spring with electrical heating and circulation of heated liquid from the cooling system.

"520"

Two horizontal carburetors Stromberg 150-175 CDET with electric automatic starting device. Marking: colorless plate.

Identification No.:

• front Carburetor: Model 1: 1 225 581 1, Model 2: 1 259 277 1;
• rear carburetor: model 1: 1 255 582 9, model 2: 1 259 278 9.

Since October 1975 - two Stromberg 175 CDET carburetors, index E 17485/1+2.

"525"

Until August 1975, two carburettors with sequential opening of throttle valves Zenith 32/40 INAT, index E 17121. Since September 1975, the front carburettor has the index E 17401, the rear - E 17402.

"528"

Two carburetors with sequential opening of throttle valves Zenith 35/40 INAT. Index of the front carburetor E 17405, rear - E 17406.

Basic calibration data for carburetors

Note: Needle valve hole diameter, mm:

• solex and Zenith carburetor: 2.0;
• stromberg carburetor: 1.5.

Basic calibration data for carburetors since 1978 model year

Note: Needle valve hole diameter, mm:

• solax and Zenith carburetors: 2.0;
• strombarg carburetor: 1.5.

Since the 1978 model year, the BMW "525" and "528" were equipped with the following types of carburetors.

"525"

Two two-chamber Zenith 32/40 INAT carburetors with an additional system for preparing the working mixture and a front carburetor with an auxiliary starting device.

"528"

Two two-chamber Zenith 35/40 INAT carburetors with an additional system for preparing the working mixture and a front carburetor with an auxiliary starting device.

"525" and "528"

Two two-chamber Solex DVG carburetors type 4A1. Emulsion type carburetor, two-chamber, with sequential opening of throttle valves, with automatic starting device and thermostatic auxiliary starting device (to start a warm engine). At forced idle speed, the forced idle economizer is activated.

Carburetor index:

• "525": E 17481 (E 17703)*;
• "528": E 17482 (E 17704).

* The index of carburetors installed on models with an automatic transmission with the system is indicated in brackets "Doppelmastervac". or variants of carburetors without a vacuum ignition regulator (the regulator is installed on the engine).

Calibration data for the Pierburg Solex 4A1 carburetor

Since the 1980 model year, some characteristics of the Solex 4A1 BMW "525" and "525A" carburetors have been changed.

BMW Part Number:

• "525": 1 271 372 0;
• "525A" 1 721 377 9.

"525"

Fuel supply by the accelerator pump per 1 cycle, cm³: 0.7±0.15.

"525A"

Idle air jet marking: 125.

Accelerator pump nozzle marking: 50.

Starting clearances of the air damper, mm:

• I stage: 1.1;
• II stage: 4.2+0.2.

Air damper opening, mm: 0.3-0.8.

Since the 1981 model year, the marking of the fuel jets of the main metering system of the Solex 32/32 DIDTA carburetor has been changed: 1st chamber jet: 117.5; 2nd chamber jet: 112.5.



Since the 1981 model year, the BMW "518" has been equipped with a Zenith 2B4 carburetor.

BMW part number: 12706929.

The carburetor is an emulsion type, two-chamber, with sequential opening of the throttle valves. The carburetor has a fuel drain system into the fuel tank, a pneumatic drive for the 2nd chamber throttle valve, a piston accelerator pump, a partial load economizer, a power mode economizer with a pneumatic drive, an automatic starting device with a pneumatic drive for the air damper and an auxiliary starting device (to start a warm engine). At forced idle speed, the forced idle economizer is activated.

Calibration data for the Pierburg 2B4 carburetor

Since September 1983, the BMW "518" has been equipped with a 2BE carburetor, which is a modification of the 2B4 carburetor with an electronic mixture formation system "Ecotronic", controlled by a controller, which is a specialized digital micro-computer.

Controller

Brand and type: Bosch 0 260 200 002.

Incoming air temperature sensor

Brand and type: Bosch 0 280 130 026.

Sensor resistance, kOhm:

• at air temperature:
• —10°C: 8,2-10,5;
• +20°C: 2,0-3,0;
• +80°C: 300-360 Ohm.

Thermostatic valve

• Valve opening temperature, °C: +58.
• Valve closing temperature, °C: +48.

Throttle valve potentiometer 1st chamber

Total resistance when measured between plugs "E" and "A" of the potentiometer connector, kOhm:

• when measured on a removed potentiometer: 1.3-2.5;
• when measuring without removing the potentiometer directly on the vehicle: 1.4-2.6.

Resistance between plugs "A" and "S" of the potentiometer connector when measured on the carburetor, Ohm:

• with the 1st chamber throttle servo pusher retracted (forced idle position): 0-250;
• with the 1st chamber throttle valve servo pusher extended (full load position): 1300-2500.

Collector current of the potentiometer transistor, no more than, mA; 1.

Voltage at the potentiometer terminals, no more than, V: 5.

Idle switch

The idle switch is built into the 1st chamber throttle servo pushrod. It is turned on when the throttle control lever is pulled away from it and turned off when it comes into contact with it.

Resistance between terminals when switch is on. Ohm:

• when measuring on the removed throttle servo drive of the 1st chamber: 0;
• when measured on a car: ~15.

Resistance between terminals when switch is off. Ohm: cos.

Air damper servo drive

Resistance of the actuator motor armature winding, Ohm:

• when measured on a removed motor: 0.87-1.63;
• when measured on a car: 0.9-1.7.

Insulation resistance when measured between the motor terminals and ground. Ohm: ∞.

Throttle actuator 1st chamber

Resistance of windings of vacuum and atmospheric valves, Ohm: 35-80.

Pusher stroke length, mm: 12.4-13.7.

Total resistance of the potentiometer when measured between plugs "4" and "5" of the servo drive connector, kOhm:

• when measured on a removed servo drive 1.3-2.5;
• when measured on a car: 1.4-2.6.

Potentiometer resistance when measured between plugs "4" and "7" of the servo drive connector, Ohm:

• with pusher retracted: 0-500;
• with the pusher extended: 900-1900.

Forced idling system air valve

Vacuum pressure at which the valve is completely closed, mbar: 160.

Vacuum, starting from which the valve is fully open, mbar: 270.

Calibration data for the Pierburg 2BE carburetor

"520" with a six-cylinder engine

Carburetor Solex 4A1, BMW catalog number: 12713699.

Differences in calibration data of the Solex 4A1 BMW "520" carburetor

[The original text is available on the website: bmwman.ru]