Design features of carburetors depending on the chassis number of the car
«518»
Until May 1975, a Solex 38 PDSI carburetor with a falling flow. Marking: copper-colored plate, identification number N9 1 261 264 2. Since May 1975 — two-chamber carburetor Solex 32/32 DIDTA, index E 17 386, emulsion type, with an automatic starting device of mixed type, which uses a bimetallic spring with electric heating and circulation of heated liquid from the cooling system.
«520»
Two horizontal Stromberg 150-175 CDET carburetors with electric automatic starter. Marking: colorless plate.
Identification Nos.:
- front carburettor: 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 carburetors with progressive throttle opening Zenith 32/40 INAT, index E 17121. Since September 1975, the front carburetor has the index E 17401, the rear - E 17402.
«528»
Two Zenith 35/40 INAT sequential throttle carburetors. Front carburetor index 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 from model year 1978
Note. Needle valve opening diameter, mm:
- Solax and Zenith carburetors: 2.0;
- Strombarg carburetor: 1.5.
From model year 1978 on BMW «525» And «528» carburetors of the following types were installed.
«525»
Two Zenith 32/40 INAT twin-barrel carburetors with auxiliary mixture preparation and front carburetor with auxiliary starting device.
«528»
Two twin-barrel Zenith 35/40 INAT carburetors with an additional mixture system and a front carburetor with an auxiliary starting device.
«525» And «528»
Two two-barrel Solex DVG type 4A1 carburetors. Emulsion-type carburetor, two-chamber, with sequential opening of throttle valves, with automatic starter and thermostatic auxiliary starter (to start a warm engine). At forced idle, the forced idle economizer is activated.
Carburetor index:
- «525»: E 17481 (E 17703) *;
- «528»: E 17482 (E 17704).
* In parentheses is the index of carburetors installed on models with an automatic transmission with a system «Doppelmastervac». or carburettor variants without vacuum ignition control (regulator mounted on the engine).
Calibration data for the Pierburg Solex 4A1 carburetor
Since the 1980 model year, some characteristics of the Solex 4A1 BMW carburetors have been changed «525» And «525A».
BMW part number:
- «525»: 1 271 372 0;
- «525A» 1 721 377 9.
«525»
Fuel supply by the accelerator pump for 1 cycle, cm3: 0.7±0.15.
«525A»
Idle air jet marking: 125.
Accelerator pump atomizer marking: 50.
Starting gaps of the air damper, mm:
- Stage I: 1.1;
- Stage II: 4.2 + 0.2.
Opening of the air damper, 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: jet of the 1st chamber: 117.5; jet of the 2nd chamber: 112.5.
From model year 1981 on BMW «518» a Zenith 2V4 carburetor is installed.
BMW part number: 12706929.
Carburetor emulsion type, two-chamber, with sequential opening of throttle valves. The carburetor has a system for draining fuel into the fuel tank, a 2nd chamber pneumatic throttle actuator, a piston accelerator pump, a partial load economizer, an air-actuated power economizer, an automatic starter with an air-operated air damper and an auxiliary starting device (to start a warm engine). At forced idle, the forced idle economizer is activated.
Calibration data for the Pierburg 2V4 carburetor
Since September 1983 at BMW «518» a 2BE carburetor was installed, which is a modification of the 2V4 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.
Intake air temperature sensor
Brand and type: Bosch 0 280 130 026.
Sensor resistance, kOhm:
- at air temperature:
- -10°C: 8.2-10.5;
- +20°С: 2.0-3.0;
- +80°С: 300-360 Ohm.
Thermostatic valve
- Valve opening temperature,°С: +58.
- Valve closing temperature,°С: +48.
Throttle valve potentiometer 1st chamber
Total resistance when measured between plugs «E» And «A» potentiometer connector, kOhm:
- when measuring on the removed potentiometer: 1.3-2.5;
- when measuring without removing the potentiometer directly on the car: 1.4-2.6.
Resistance between plugs «A» And «S» potentiometer connector when measured on a carburetor, Ohm:
- with the thruster of the throttle servo drive of the 1st chamber pushed in (forced idle position): 0-250;
- when the pusher of the throttle servo drive of the 1st chamber is extended (full load position): 1300-2500.
Collector current of the potentiometer transistor, no more than, mA; 1.
Voltage at the potentiometer terminals, not more than, V: 5.
Idle switch
The idle switch is built into the throttle servo tappet of the 1st chamber. It turns on when the throttle control lever is pulled away from it and turns off when it comes into contact with it.
Resistance between terminals when the switch is on. Ohm:
- when measuring on the removed throttle servo of the 1st chamber: 0;
- when measured on a car: ~15.
Resistance between terminals when the switch is off. Om: so.
Air damper servo
Winding resistance of the armature of the executive motor, 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 terminals of the motor and «weight». Ohm: ∞.
Throttle valve servo 1st chamber
Resistance of windings of vacuum and atmospheric valves, Ohm: 35-80.
Pusher stroke length, mm: 12.4-13.7.
Total potentiometer resistance when measured between plugs «4» And «5» servo connector, kOhm:
- when measured on a removed servo 1.3-2.5;
- when measured on a car: 1.4-2.6.
Potentiometer resistance when measured between plugs «4» And «7» servo connector, Ohm:
- with pushed pusher: 0-500;
- with the pusher extended: 900-1900.
Positive idle air valve
Vacuum to which the valve is completely closed, mbar: 160.
Vacuum, from which the valve is fully open, mbar: 270.
Calibration data for the Pierburg 2BE carburetor
«520» with six-cylinder engine
Solex 4А1 carburetor, BMW part number: 12713699.