How about we try to make sure we're all on the same page? This forum is here for us to help each other. I apologize for not using the correct MB language, as I learned this engine before I got the manuals.

First item of business is that gorilla knob. Cable from the knob to that oval "slot" connector. Push the gorilla knob all the way in means pushing the slot against the pin and shutting down the fuel or shutting down the engine. Pull the gorilla knob all the way out and the starter engages. The slot also pulls and holds the pin, which means the engine gets a little extra shot of fuel for starting. Release the gorilla knob and the pin floats in the slot. The adjustment here is to make sure all three events happen, meaning the pin gets pushed, pulled, and floats. If you can't get all three events to happen through normal adjustment then the cable is stretched and should be replaced.

Second item is the foot throttle/accelerator pedal. Pedal rotates the rod running along the firewall, the rod opens and closes the butterfly valve in the throttlebody/mixing box. A spring, external to the mixing box, closes the butterfly valve and lifts the foot throttle. There are no connections between the foot throttle and the IP, in this sense. Two adjusting screws at the throttle body. The first adjusting screw limits how far the butterfly valve can close (this also adjusts the amount of vacuum the governor sees). This is the low idle mixture screw. We perceive this as changing the low idle speed, but it's the mixture that dominates. The second screw is the no-load high rpm limit. Adjusting this will not appreciably change the mixture due to the high speed of the air in the air duct at high rpms. In other words, 200rpm change at 4000rpm isn't going to change the mixture enough to make a difference. I'm assuming here we're not abusing the engine in normal driving.

Third is that linkage running from the throttle body, over the top of the valve cover, then down and between the IP and the engine. This is the idle damper. Remember, at low idle the engine compression is just barely losing the battle with the crankshaft momentum created by combustion. If the idle mixture is set too rich then the engine will run without the idle damper. If the idle mixture is set too lean and the idle damper is taken away then the engine will sound like a Harley and die. This is because the rack wants to float at low idle, due to the rapidly changing vacuum in the throttle body, or pulsing. The air speed in the duct simply isn't fast enough to overcome the effects of the cylinder compression/expansion events at low idle. The idle damper prevents the extremes of the rack float. The adjustment is to set the low idle mixture too rich, disconnect the idle damper, lean out the low idle mixture until the engine stumbles, then turn up the low idle mixture a smidgen and reconnect the damper. Then road test to make sure the car can take off in low gear. daBenz is set up so that I can slowly let out the clutch in first gear and the engine doesn't stumble.

Fourth is the high idle knob. Fisherman's may be integral with the gorilla knob, daBenz has a separate knob. At any rate, what it does is override the low idle mixture screw by pretending it's the foot throttle. And nothing more. Adjust the cable to where you want, making sure it doesn't affect anything at low idle. I like a little slack at low idle, just to make sure.

Hope this helps. To me, this is the simplest engine control I've ever seen. After a lot of thinking and tinkering, that is. I fully understand Fisherman's confusion/frustration, and I admire his courage to dive into it.

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daBenz - 1970 220D