Q: My car is a 1971 HF Lusso with standard Solex carburation and unmodified save for some cylinder head work 1600 motor. The problem I have is that with the idle adjustment backed right off, and the carbs balanced, I cannot get an idle speed below 1400rpm when the car is warmed up.

The motor was rebuilt four years ago, and reconditioned carburettors fitted by the previous owner. The throttle operating mechanism seems fine, and is returning the operating arms properly as far as I can see. The throttle cable is not too tight to not allow the throttles to close properly. The balance between the carbs seems OK in that the car runs well and pulls away smoothly. In fact, except when it is idling, it runs exceptionally well. I have not taken the carbs off and was hoping that there would be some simple answer to this..... (there usually is with Fulvias!) The high idle speed makes town driving a pain.
Jonathan.Grantham@wdr.com

A: Let me try to provide some clues to your Fulvia carb problem. I imply that you have already established that the ignition is correctly set up and the timing is right. If the idle speed is too high, there is probably an air leak somewhere.
First, check if the vacuum hose to the brake servo is intact.
Second, is the carb rubber mounting block damaged by a split or is it perished? Are some of the carb gaskets damaged or even missing?
Third, are the seats of the four idling screws ruined?
Fourth, can you drop the revs by physically pulling back the throttle pedal? If so, the bulkhead seal through which the throttle cable runs is swollen and it gets worse when the engine is hot.
Fifth, never assume that the carbs are balanced unless you check them with the appropriate equipment. In my experience they are usually a long way out of balance.
Sixth, excessively high idling will eventually ruin the cyinder bores and pistons. This is not a trivial point.
- Andrea -