This section describes the procedure for the 2B4 carburetor. The procedure for the 2BE carburetor is similar.
Cleaning
1. Purchase a complete set of gaskets and seals for your carburetor.
2. Wash the outer surfaces of the carburetor.
3. Using a screwdriver, unhook the accelerator pump rod from the throttle lever of the primary chamber (shown by arrow).
4. Loosen the bolts securing the cover to the main body. A bar wrench is required to loosen the center bolt.
5. Unhook the link from the plastic choke lever (shown by arrow).
6. Detach the cover from the main body and remove the gasket.
View of the lid from the inside.
View of the carburetor without cover.
7. Turn away the screw of fastening of an arm of a drive of a throttle to the case of a throttle. (shown by arrow).
8. Disconnect the vacuum drive rod from the throttle lever of the secondary chamber.
9. Remove the screws securing the throttle body to the main body.
10. Unhook the intermediate throttle link. If this turns out to be difficult, then unscrew the nut and disconnect the lever from the throttle axis of the primary chamber, taking measures not to damage the return spring.
11. Disconnect the throttle body from the main body and remove the gasket.
Bottom view of the main body without the throttle body - pay attention to the gasket:
12. Turning the cover over, push out the axes of the floats, remove the floats...
...and remove the needle valves - keep them as they are.
13. Unscrew the direct fuel jet from the secondary float chamber,..
... then unscrew the jets from the cover in the same way - keep them in accordance with the location.
secondary main jet (1) and fuel jet TM (thermo starter) (2).
secondary main jet (left) and fuel jet TM (on right), wrapped in a lid.
Secondary direct air jet (1), air jet TM (2) and corrective air jet (3).
The position of the jets in the cover (shown by arrows).
14. Clean all components and purge internal passages with low pressure air.
15. Assembly is the reverse of disassembly, however, pay attention to the following points:
- Install new gaskets and seals from the repair kit.
- Before installing the cover, check that the choke rod is properly connected to the lever.
- Check and, if necessary, adjust the float settings. Turn cover over and check distance from mating surface (without gasket) to the top of the float, making sure that the spring-loaded ball of the needle valve is not pressed. Note that this distance is not the same for primary and secondary floats (Look Table of sizes and adjustment data at the end of the guide). If adjustment is required, bend the float arm as required.
- Make sure the oil seal is installed at the top of the accelerator pump.
Adjustment
Adjustments of turns of idling and quality of a mix are stated in the Chapter Car maintenance.
Automatic choke (2B4)
1. Check that the alignment marks of the body and the cover of the automatic air damper are clearly visible; if not, apply new marks.
2. Loosen the three screws and remove the metal ring.
3. Remove the plastic ring while disconnecting the bimetallic spring from the control lever.
4. Attach a rubber band to the bottom of the control lever (2). Press the lever to the right and drill with a diameter of 4.2 mm (1) check the distance between the lower edge of the choke and the carburettor wall. To move the lever periodically act on the vacuum drive with a vacuum.
5. If adjustment is needed, turn arrow shown) at the end of the vacuum drive.
6. Install the cover in reverse order, making sure the marks are aligned.
Throttle drive (2B4)
1. With the throttle in the idle position, check that the length of the spring is 23.0±1.0 mm. Otherwise, adjust with a nut.
2. When there is no vacuum (engine not running), check that the stroke of the lever, measured between the stop screw and the lever, is 5.0±0.5 mm. If necessary, loosen the lock nut and rotate the diaphragm rod. After adjustment, tighten the lock nut.
Throttle drive (2BE)
Intricate adjustments to the 2BE carburetor require special tools. Therefore, this work should be entrusted to a BMW dealer.