What is the black plastic thumbscrew thingy near the idling screw?

I had a mechanic look at my car the other day when I'd broken down and he said this isn't the idle screw and instead adjusted the metal bolt and nut arrangement that is connected to the accelerator I think (you loosen the nut then screw the bolt in to increase idle).

But my Haynes manual says the black plastic thing is the idling screw, however when I turn it doesn't seem to do a lot anyway?

What is it? Idle screw? Micro adustment idle screw? Mixture? Radio tuner button?

I'd love to know.

Also, my 245 has a dash arrangement I've never seen in another Volvo of this type - it has a tacho and speedo in the middle and on each side of these has two round gauges - Voltmeter and Temp on the left, Oil pressure and fuel on the right next to the speedo. Is this particularly rare? Is it from a 242 perhaps?


Klaus Fluoride
1978 245 DL (unwell)