Idle adjustment screw

[That]

Does idle adjustment screw on 1982 fiat 2000 have a locknut? I do not see one and the screw is very very easy to turn. Can almost turn by hand. I realize the idle speed screw has a locknut, but I am referring to air adjustment screw. Thanks to all.

[RRoller123]

No it isn't necessary. There should be an O-ring that gives it plenty of resistance and holds it at setting. Turn it all the way out and you should see a groove in the shaft of the screw. If there is no O-ring, there is your answer. If there is one there, it is likely extremely worn. Now..... The actual size and OTC availability of this O-ring is a source of great mirth, merriment, debate and myth here on this forum.

[That]

Thanks. I love your command of the English language. Have a good one.

[KevAndAndi]

I replaced the o-ring with what I believe to be the correct size. The screw still turns by hand. I have wondered whether it might be a good idea to use on it the "weakest" Loctite version.

[azruss]

when I replaced mine, a found the best fit from a metric o-ring kit. Mine also turns by hand. For the most part it stays put. If i think the idle is getting a little rough, i go in there and adjust it. Have to do it maybe once every 6 months.

[RRoller123]

Same here. The actual size of the damned thing is a mystery. The closest metric one that I have found also holds it, but you can still turn it by hand with some effort. Doesn't seem to be a problem though, and I don't think it leaks air. Maybe a tiny bit of petroleum jelly on the o-ring would help, but I don't do this. The commonly held belief that it is 3/8" OD, 1/4" ID, with 1/8" wall thickness obviously doesn't add up, unless the cross section is oval, which it isn't.

[KevAndAndi]

After reading this, I realized the cross-section diameter of my o-ring was too small. It was 1/16".

To replace it, I got the #78 o-ring at Ace Hardware (7/16" OD, 1/4" ID, 3/32" wall). These measurements equate to approximately 11.1 mm OD, 6.4 mm ID, 2.4 mm wall.

However, once it was in the idle speed screw's groove, the screw was impossible to get in the hole. The ring was blocking the screw from entering. So I positioned the ring on the threads ahead of the groove before putting the screw in. That way, the outside edge of the hole squished the ring and rolled it into the screw's groove, and the whole deal went inside without a problem.

Now, the screw doesn't turn excessively easily.

[4uall]

this might help

http://www.artigue.com/fiatcontent/microfilm/22-B.pdf

Lists every part number for everything in the FI system. You may be looking for parts that were not sold as individual units; i.e. the throttle body parts were generally sold along with the entire plenum top. However, some help:

The idle speed screw O-ring is 10mm OD and 6.5 ID. I can buy them at Ace Hardware near my house, they are in a big O-ring rack and won't deteriorate when exposed to fuel/ethanol.

Is the top picture of your throttle body with the accelerator removed? I can't tell which side that is, the TPS side? Look at the microfilm page 46, it shows the entire throttle linkage with all P/Ns.