High idle after electronic distributor replacement

[stuartrubin]

After a complete distro failure, my mechanic replaced it with an electronic distributor module (I believe this one: https://www.vickauto.com/FIAT-PARTS/FIA ... KU-21-6325). Now, after the car warms up, the idle is VERY high (like 2500 RPM).
He mentioned that when the distributor failed, the timing chain slipped a couple of teeth, and he fixed that, and adjusted the timing.
Is the distributor fix (upgrade) somehow related to my idle speed?
There is a vacuum line connected between the distributor (that metal "UFO" on the side, whatever that is!) and 34 ADF carburetor, so I guess the the two parts are related.
Any ideas on how to get the idle back in check?
Thank you (as always)!

[Nut124]

Stuart, there is no timing chain.

There is a timing belt for the cams but they have nothing to do with the distributor.

Likely your distributor timing was retarded with the old dizzy resulting in weak idle and need to turn up the idle speed screw to keep the engine running.

Now, perhaps there is more ignition advance and the engine is happy with strong idle. I'm surprised the mech did not adjust the idle speed. He should know how. I'm no expert on your carb. Usually, there is a screw that sets the carb butterfly position at idle. This determines the idle speed and it needs to be turned down.

[stuartrubin]

there is no timing chain.

Ooops! Just a momentary brain fart, but I did mean "belt"! Thanks for the correction.

Likely your distributor timing was retarded with the old dizzy resulting in weak idle and need to turn up the idle speed screw to keep the engine running...Now, perhaps there is more ignition advance and the engine is happy with strong idle.

This is actually sort of the answer I was hoping for! Since it ran fine while warming up, it's entirely possible that he just didn't wait long enough.
Over the years, for various reasons, I have gone through the full ADF setup procedure with mixed success (particularly mixed with regards to the idle). (Carburetor "mixed" success , no pun intended!) Maybe now that the timing and dizzy are "right" I can get the carb properly adjusted.

The other possibility I have considered is a newly created vacuum leak, which might also have the same issues. I may be able to find it if it's there.

Hopefully, I will have time this evening and will report back.

Thank you

[stuartrubin]

So, most likely, after having the engine running better because of the timing and the new dizzy, all this took was a turn or two of the idle speed. It's running great now. Thanks

[spider2081]

I don't know, does your car have a vacuum advance on the distributor. If so have you observed if it works?? I have see screws that hold the distributor pick up too long and lock the vacuum advance by bottoming out. Vacuum advance operation can be observed by watching the shaft from the diaphragm to the distributor move as engine RPM is changed.