Technical Stuck throttle

I've got a 327 with a Carter AFB that sticks at about 3 or 4 hundred RPM over the set idol. All I have to do to reset it is to just blip the pedal at a stop light and it will go back to the set idol or instead of coming to a slow stop at a light I can quickly come off the pedal and jerk the car.
I can recreate it in the drive way and the throttle stop is on the idol adjustment screw and the only way I can get it to calm down is by grabbing the throttle arm and put downward pressure on the arm.
Does this sound familiar or ring any bells for anyone out there?

 

Sounds like a weak return spring to me if it isn't returning to the correct idle.

 

Or the angle its pulling.

 

fast idle cam? One of my 97s has a choke that likes to get in the way of a low idle, usually after I have been belting it a bit. I only choke the center carb and this is one of end units. Acts a lot like the OP describes.

 

If it is in that 62 Check your motor mounts to make sure they (especially the left) aren't broke or bad.
All of the above suggestions are good and well worth checking though. I drive an ot single barrel six cylinder truck a lot that I need to figure out why the fast idle cam sticks and keeps the throttle open to far. Pretty much the same results that you get. It will work ok and then the idle doesn't want to come back down.

 

Or it could be wear on the throttle shafts and body causing this...

 

may be a ****erfly sticking

 

could be lots of stuff. Perhaps you'll have to do some troubleshooting?

If you post a picture or two of the carb, linkage, spring, etc we might be able to be more helpful

(also, idle is spelled idle, not idol, when you're talking about cars)

 

My choke is set up but my fast idle circuit isn't, it just sets there not touching anything. I can't see it being a linkage problem or a spring return problem because the throttle stop is against the throttle adjustment screw, you can press the throttle stop up against the adjustment screw and nothing changes. I am open for suggestions if you have an idea.
I just rebuilt this carb last summer and it ran fine up until this winter. Other than this high idle problem it runs great.

 

When the throttle is closed, and you disconnect the linkage rod from the arm on the carb, is there "free play", or do you have to pull on the rod a bit to get it to go into the hole? There should be some free play, if not, unscrew the part with the pin that goes into the arm, a few turns.

Nice pictures

 

See if you can move the throttle shaft up and down or front to back. If so, you need the throttle shaft bores re bushed to remove the slop. That is why it does not go back to idle, with worn throttle shafts the ****erflies land in a different position every time the throttle is closed.

 

I would recommend adding a second throttle spring for safety. Who knows, it may solve your problem...

 

Bingo!

 

If the throttle is returning to fully rest on the adjustment screw but the idle is abnormally fast, There is extra air momentarily leaking in somewhere. It could be the throttle shaft like everyone is mentioning, but it would odd if "blipping the pedal" settled it down. I'm thinking more like the throttle plate screws are loose and they are vibrating out of position.
After a trip, pull in your drive or a safe place to get under the hood, shut it down with the fast idle and check the throttle plates with a strong flashlight. You might even use a strip of copy paper as a shim but don't drop anything in there. Put a little torque on the throttle and release and see if the gap changes. And if that checks out, then wiggle the shaft to check for slop.

 

There's play in the linkage in fact I need to buy the bushing that goes between the firewall rod and the carb rod, it kind of just flops around

 

I had an Edlebrock carb that would do that. Finally got a new gasket and tightened the mounting bolts equally and that fixed mine

 

I never took the throttle plates off during the rebuild, it didn't look like they had ever been off, I'll take a look at them, I'd hate for one of thos screws to fall out. Sounds like I need to check for play in my throttle shaft. Should there be any play at all, I don't remember there being any excessive play at least nothing that caught my attention?

 

My 750 Eddy does that if I drive in the rain with the hood sides off. I squirt some WD-40 on the throttle shafts and it's fine. Give it a try, it's cheep.

 

Was the gasket getting rubbing the throttle plates?

 

Check to make sure choke is opening all the way. If it doesn't open the choke plate all the way, it could cause the problem.

 

I don't think so,but maybe. I just thought the body may have been "tweaked" slightly and caused the shafts to bind by uneven mounting bolt tightening

 

Looks like the fast idle rod (connecting the fast idle cam and the intermediate choke arm) is on the wrong side of the intermediate choke arm. Check the operation of how the dog on the intermediate choke arm moves with the choke shaft arm. Looks like it is 180 degrees out.

Jon.

 

I agree with carbking check out the second picture at the top, looks like it is pushing the choke shut.

 

Sorry I'm just now getting around to looking at this again. My choke is opening fine, the fast idle circuit isn't set up, I'll try and find some pics in my manual to see how its suppose to be set up like

 

I do have some upward movement on the throttle shaft, its enough to hear a clicking sound when I move it up and down. It's odd that it just started showing up 1000 or so miles after the rebuild.
The throttle return stop has a slight concave spot where it has rested against the idle screw. I thought about trying to flatten that concave spot out, maybe its putting the shaft in a wierd angle.
Is my throttle return spring in the right spot, its doubling as a cotter pin?

 

I'm also missing the piece that the return spring hooks on to, my spring is acting as the cotter pin, I'm missing the spacer that my sample pic has.

 

Nathen - even if the choke is not working, the geometry of the linkage is keeping the fast idle cam in the wrong position, and the fast idle adjustment screw is sitting on one step of the cam, rather than being completely off the cam, as it should be when the engine is warm in your picture.

The choke function, along with controlling the fast idle circuit, also controls the secondary lockout.

Would suggest making all of this functional, but if you decide not to use a choke (bad idea on a street engine), then remove the fast idle rod, fast idle cam and screw, and the secondary lockout link.

Having a function choke is ALWAYS a good idea on a street engine, especially if there is much in-city driving.

Jon.

 

Looks like you found your problem.

 

Use two springs anyway,every one should,hook them up to two spots so if one fails the other will still close.

 

My choke works like it should and moves fine. The fast idle circuit isn't really working at all, I have to keep my foot on the gas until I can get some heat in the manifold. Next time I get it out I'll just take the fast idle screw out and put it in my pocket, maybe it does touch something every once in a while?