Engine Timming

[bradartigue]

To clarify something - the advance mechanism shouldn't move at idle, with or without the hose pinched off (and remember, you pinch it off, not just disconnect to open air). I added the pinch-off step to the procedure for a couple of reasons:

(1) I was helping people set their idle (over the phone typically) and having minor problems, then realizing the diaphragm was busted and the carb was getting unmetered air from the connection. The goal here was to eliminate the distributor vacuum line as interfering with the idle setting. I'd then have them reconnect it and, if the idle went up, the diaphragm was likely bad.

(2) On the FI cars the general rule was to pinch off all sources of air (AAR, distributor, brake booster) when diagnosing the FI system, then reconnect these in series to diagnose any false air from these devices.

I'm not sure if any of this was published by FIAT, though in the catacombs of the mind I recall this as being part of their diagnostic procedure as well.