Crazy high idle

[wipeout]

Hi,

My high idle takes for ever to come off. And most of the time does not idel at the correct speed (1600rpm) instead it will be at 14000 and when I blip the gas it will slowly rise to 2000 rpm and then back down to around 1700 - 1500.

I know that when you blip the gas the high idle is supposed to come off completely. The engine is not supposed to start revving even higher???

Any idea what I should look for. Thanks.

 

[WARVET]

Without more info, it could be alot of things. I would first check the idle setting, and mixture setting on your carb. Then timing, then vacuum leak... geesh it could be lots of things.

Was it idling correctly before? Did this just change, or has it always been like this?
When was the last time you gave her a tune up? Have you made any changes to the motor (performance stuff)? It's kinda hard to say without knowing more.

 

[JohnZ]

Make sure the choke linkage and fast idle cam are operating freely - sounds like it's gummed up or stuck.

 

[wipeout]

I checked all the vacuum lines. And no evident leaks anwhere. Im pretty sure its something to do with the high idle cam. Because If I let the engine run for awhile and then push down on the cam it disengages.

Almost like it's getting stuck or the carb is screwing up some other way. Any ideas what to do.

Also I noticed that somethis the engine idles rough and there is black smoke that comes out of the exhaust when I first start it. Anybody know a good tutorial on how to do a proper tune up on this baby.

 

[JohnZ]

The engine tune-up and carburetor sections in the shop manual will take you through the choke and fast-idle troubleshooting and adjustment procedure.

 

[wipeout]

OK, The book I have is not very detailed on how to do this. Which one do you recommend. You propably mean the actual shop manual from gm right.

 

[wishuwerehere82]

Wipeout,

It sounds like your power valve may be stuck partially open, or something is sticking in the linkage causing it not to close all the way to the idle stop. Try tapping on the Choke plate on the secondaries to see if the idle goes back to normal. The Power valve is linke to the choke plate and it may shed some light on the problem.