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-   -   High idle after choke opens (https://www.thirdgen.org/forums/carburetors/669543-high-idle-after-choke.html)

JLCustomizing 12-27-2012 11:40 AM

High idle after choke opens
 
Ever since winter hit, my car revs up to about 2k after the choke is fully open. I havent adjusted anything and when it was warm out it idled great. The carb is a fresh rebuild about 6 months old with Cliffs kit so I know the internals are decent. I do have pretty old throttle return springs on there. Would this cause a problem of a higher rev if they were going bad? The choke opens fully and within the 30 second realm. The idle during choke is great, just after the choke is open it acts up. Its a 77 quadrajet off a Corvette.

naf 12-27-2012 12:13 PM

Re: High idle after choke opens
 
Verify that the throttle stop is coming off of the fast idle cam when the choke is open. Blipping it should allow the cam to fall away but it may be getting stuck.

JLCustomizing 12-28-2012 03:43 PM

Re: High idle after choke opens
 
Well I changed the throttle return springs with no luck so on to the fast idle cam. Also, since all this has been happening my car wont start half the time, I'm just getting a click. The battery is 2 months old and showing a good charge, the lead wire to the starter is good. Could this be tied in somehow or a whole seperate issue.

EDIT *I checked over my fast idle cam and it doesnt seem like it would have any reason to stick, everything is lubed up anyway. Is there a way to adjust that? I have a little play in the shaft that goes up to the side of the choke flap, is there anyway i can tighten that as well?

Ingram78 12-28-2012 06:50 PM

Re: High idle after choke opens
 
Vacuum leak maybe? Or Vac advance on distributor?

naf 12-29-2012 07:25 AM

Re: High idle after choke opens
 
Play is normal. Battery unrelated. Check your alternator, it may have killed your last battery. Most of the parts store chains will test both for free, but make sure you've got a good cable connection to everything first: starter/alternator/grounds.

eseibel67 12-29-2012 03:01 PM

Re: High idle after choke opens
 
First of all, the choke fast idle "hammer" should not be lubricated or it will collect dust and get sticky. It should just fall free and loose on the choke housing. Take it apart and lightly clean it with sandpaper.

Your fast idle problem is in the adjustment. My guess is that you currently have the angle of the choke flap too far rich (closed) on cold startup. In order for the engine to run cold under these too-rich conditions, the fast idle speed has been cranked up to compensate. When the choke reaches temp and the choke flap opens full, the fast idle is way too high.

naf 12-29-2012 05:01 PM

Re: High idle after choke opens
 
The fast idle cam should be 'green' which is the teflon coating on it.
Don't sand the coating away. Just clean it well.

If your alternator isn't charging correctly it might not be providing the 12 volts your choke needs to open (although you say it's opening fully?). The choke gets its power through the alternator so it only starts opening when the engine is running. I'd fix your electrical problems before going any further. Don't start adjusting anything yet: make sure everything is working correctly first.

Camaro305SB 12-30-2012 01:06 AM

Re: High idle after choke opens
 
If I'm not mistaken fast idle is pretty high on these cars. Mine will slowly creep up to 2k when its warming up unless I tap the gas to kick the idle down. Runs like a CHAMP otherwise and starts right up in the coldest/hottest temperatures.

eseibel67 12-30-2012 06:43 AM

Re: High idle after choke opens
 

Originally Posted by naf (Post 5453202)
The fast idle cam should be 'green' which is the teflon coating on it.
Don't sand the coating away. Just clean it well.

Of course, do not sand the green cam. It's the round surface of the aluminum choke housing that the cam pivots on that if oxidized, could prevent the cam from falling smoothly. That's the part that might need the light sanding.


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