High Idle cold Carb to 4k rpm

[parkersnine]

After starting (89 dx 5 speed) will lope at low idle. Today after driving it about a mile at a red light it revved to 4k rpm and stayed there during the light and would not "kick down." The temp in Ga is pretty warm even at about 7:30am-say low 80's. This afternoon when I reached the first stop sign cold it again went to 4k rpm and hung out there while the traffic cleared. At the next stop (only a half mile away) the idle chilled out to normal and remained chilled out the rest of the short drive home.

[mcastro_m]

Does the carb handle the AC? Were you using it?.
Is that happening only some mins later after you start up the car?

I'd recommend you:
- check the choke
- check the AC conections on the carb [right side]
- clean the gas cable conections on the carb [left side]

[parkersnine]

The a/c is disconnected. Not on.Yes it happens cold then after a few miles or at next stop light or sign it is okay. Today after driving it 5 miles it sat for 45 min then it did the high idle again at the first intersection.

[mcastro_m]

Open the hood and watch for the behavior when that happens and let us know what you see, do it with the neutral gear - handbrake, pushing the gas several times below 3000rpm. After the heat is ok, continue doing that to try to reproduce the problems.

[greentee76]

Two things come to mind:
If the thottle control diaphram (vacuum pot on passenger side of carb) is unplugged it will idle high like this, check to make sure vacuum hose to it is not cracked.
Also make sure that the cams on the carb (passengerside and driversside) that connect to the mainshaft of the carb are tight. I had one that had loosen and would produce an eratic idle.

.

[A20A1]

Definitely keep an eye on the throttle controller.

Check your coolant level also and bleed the cooling system a little just to be sure.

[Inferno]

Had that problem before. It's a choke spiral. You need to readjust it. Some have screws but some have rivets. If screws then it's easy. Rivets you need to drill them and install screws.

[A20A1]

It might be the fast idle cam related but I've never had mine coming on oddly like that so can't really help you much there.

Also might want to see if your carb is dirty in the barrels or something is kinking or even melting the throttle cable under the hood. If you find your throttle shafts are binding they could be too tight or as greentee76 suggested it might be loose, in either instance it could be a result of a previous rebuild of the carb or simple age.

A/c shouldn't be the problem because that has the least amount of idle movement on the diaphragm.

Are you automatic?

also let me know about your coolant situation.