Diagram of the device for supplying exhaust gas to the carburetor throttle valve
In the lower half of the carburetor body 1, where the throttle valve 2 is located, there is a process plug 5 above the idling adjustment screw 6 (emulsion screw), which must be drilled out. Behind it will open hole 4, ending channel 3 of the idle system. In the hole you need to cut the thread M8x1, and drill the channel to the diameter. 6. The channel must be drilled exactly along the axis of the threaded hole. To do this, you need to make a sleeve-conductor with an external thread M8x1 and a hole diameter. 6 mm, screw the jig into hole 4 and drill out through it. The diameter of the channel 3 on opposite sides need to cut through two shallow horizontal grooves. This is necessary so that when you push the throttle pedal abruptly, there will be no failure of the engine rpm.
At this, the alteration of the carburetor, which with the minimum plumbing skills is available to the motorist, ends. Minimal reworking of the intake manifold 7 is needed. In its flange 8 in the zone of nozzles through which exhaust gases from the 2nd and 3rd cylinders are removed, it is necessary to drill a through hole and cut the thread M8x1. Additional details will be required: a copper tube 9 and two fittings 10 and 11. Fitting 10. need to be screwed into the body of the carburetor, and fitting 11 - into the flange of the exhaust <manifold. The copper tube should be 8x6 mm in diameter with two cap nuts. The design of the ends of the tube together with cap nuts must ensure the tightness of the connection of the tube with fittings.
After connecting the pipe to the fittings on the carburetor and on the exhaust manifold, you can start the engine. Part of the exhaust gases from the 2nd and 3rd cylinders will go under the throttle and begin to perform their noble task: not only to save fuel by 25%, but also to reduce exhaust emissions by half.
Literature: Journal "IR" number 11/91