Fulvia fast idle solenoid

[9JOT]

A quick question, more to satisfy my curiousity rather than solve a technical issue: what on earth is the fast idle facility on the Fulvia? I notice it requires a solenoid and a sensor on the clutch. It's only come to light because I'm rewiring my car and I came across the references to it in the original wiring diagram. I've fitted Dellortos and so the question is purely academic but I'm interested to know what it's purpose was and how did it operate.
Bob

[Huib]

In the early 70's we had an oil crisis. Car manufacturers tried everything to reduce petrol consumption (often counterproductive). There was also a switch on the gearbox. It was wired such that the solenoid cut off the idle jet when the car was braking on the engine. Not too much later Lancia sent a letter to the dealers to throw away the carbs and mount carbs without the solenoid. That is more or less the story as I picked up over the years.

[Simon B]

See attachment from Service Dept Document on Anti-Pollution Carbs.

PHH E2 carbs had the slow running device, not sure about the E1 carbs but it was removed on the very last Solex PHH E3 carbs.
The slow running device requires more effort to set up, plus in addition to the device you have the solenoid and two switches. Much more to go wrong for little or no benefit.
I replaced my E2 carbs with the E3 variant last year and they have been performing well.
Regards Simon

[9JOT]

Thanks for the explanation, I don't need to commit any more bandwidth puzzling ovr it!