Another high idle question

[TulsaSpider]

I have a issue that I seem to see on here a bit but never seem to get the root cause except for vacuum leak. Mine idles, when it is fully warm, according to my tach at around 1500RPMs. When it's cold it seems it's choked too much and stumbles and smokes black at idle (barely idles but won't die) for a few minuits then clears up just fine. As it is heating up the idle is around 1000 then climbs to 1500 when fully warm. I have tried to adjust it a few times with no success. I have found no vacuum leaks and all the old emissions stuff is capped. I can deal with it but I am the kind of guy that it really starts eating at me sitting at a stoplight, not to mention I am sure it would run cooler. Speaking of that if it is on the 190 degree marker and I am driving around it is hard to start. It takes a few tries and it seems to start simultaneously as the starter kicks off. This is a bit concerning as well, but it has started every time it just takes a bit.
This is why I was posting... it got me thinking...
I got my speedo cable from IAP today and was reading through it. I noticed that it said that if you can't get your car to idle down below 1500 then replace your Carburetor Idle Cut-Off Solenoid.
Sooooo guys whaddya think???? Does this sound right?? The car runs great otherwise so any input from the Fiat Guru's is appreciated!!!!
Thanks in advance!!!

[mbouse]

what carb are you running?


you can check the idle solenoid rather easily. shut the engine off, then turn the key on. now shut the radio off so you can hear. pop the hood and locate the idle solenoid. pull the wire from the solenoid; did it click? put the wire back on; did it click?

if you answered yes....my bet is that a new solenoid is a waste of money, and you are (like me) using too big of a carb to idle that 1800 engine. smaller idle jets could be in your future.

[So Cal Mark]

don't buy a solenoid, it won't help your problem. smaller jets are not the solution either. The reason it's idling slower when cold is that the choke is not open enough (you already diagnosed that problem of overchoking), so not enough air is entering for the amount of throttle opening you have. If you have turned the idle stop screw all of the way out to ensure the throttle is closed, check for vacuum leaks, then check the set screw on the secondary throttle plate. Someone may have adjusted it so that plate is partially open

[TulsaSpider]

I have been told it's a 32 ADF and It looks like the diagram in my book... here's a pic of when I first got it.

My solenoid does click and if I disconnectect it while idling it stumbles so I guess I am good there. Yep I have adjusted the throttle screw all the way out and it didn't seem to help bring down the idle while warm. I also adjusted the linkage to make sure that had adequate travel as well. I consulted my book and I didn't see the set screw for the secondary throttle plate on the diagram I have. Where is that and how should it be set? I have got to get a new book! Mine was published in '78 and is in pieces the 2nd page on how to set the idle is missing LOL! Is there a link you can give me for the procedure?
So I need to adjust the choke fast idle adjustment screw and open it up a little I suppose?
Any ideas why it's having trouble starting when hot?

[So Cal Mark]

the problem with the choke is the pull-off diaphragm. There is an adjustment screw on it to set choke opening dimension, but the diaphragm is probably no good. The secondary throttle plate set screw is quite small, and inset into the base of the carb, on the same side as the idle speed screw

[vixenkitty]

I found this link with a ton of good diagrams

http://www.artigue.com/fiat.php#Carburetor

[TulsaSpider]

Vixenkitty eh?? hmm I like that! I have been on the Artigue site before and just saw the exploded diagrams, mostly in Italian.... but I have found the engine maintanence and modification PDF which seems to have the procedure, and I'll check out the throttle plate set screw next time I get the urge to mess with the carb again!
Thanks !! I'll report back when I have something to report!

[JeremyB]

Dont know a damned thing about carbs, other than I have the same one as you do. But, I recently learned a trick for startiong the car when hot. All the time actually. When you turn you raccessory power on, the fuel pump kicks on too.
So try this. When startign th ecar, turn accessory power on, and wait 5 or 6 seconds. Then start the engine. I was told this gets gas back up to the carb to avoid hard starts. I tried it, and my 76 starts a hell fo alot easier when I do this.
Hope it helps.

[TulsaSpider]

For some reason you must have an electric fuel pump which I don't have. Glad that works for you!
Clark

[TulsaSpider]

Huzzah! I got it down to a very nice idle this afternoon!! I adjusted the "fast idle adjustment screw" down and that brought the idle down to a very nice level, then I adjusted the mixture as bit, took it out for a drive, let it heat up really good, and it stayed put!! It even accellerated better!! WooT! It idles perfectly now!! It seems to run a bit cooler too!!
Clark is a happy camper!!
Thanks all!

[bradartigue]

Huzzah! I got it down to a very nice idle this afternoon!! I adjusted the "fast idle adjustment screw" down and that brought the idle down to a very nice level, then I adjusted the mixture as bit, took it out for a drive, let it heat up really good, and it stayed put!! It even accellerated better!! WooT! It idles perfectly now!! It seems to run a bit cooler too!!
Clark is a happy camper!!
Thanks all!

Very cool. Buy some carb cleaner and clean the hell out of that thing and it will work even better. The grime factor is a bit high - dirty outside is usually a bit dirty inside as well. You can blow out the emulsion tubes through the air correctors and remove the idle jets to blow out those orifices w/o disassembling the carb.

[TulsaSpider]

I have cleaned it up nicely since this pic was taken, which was just after I had bought it. Thanks !!!