1962 Carter AFB Problem

[Junky]

On my 1962 Carter AFB, the throttle shaft end linkage doesn't close tightly enough for the linkage to touch the idle speed screw. I can manually pull it back, but it seems as if the spring isn't strong enough to pull it back all the way. I have adjusted the idle mixture screws for the best idle, and it seems and this is with the throttle linkage totally closed. The idle is still too high to put the car in gear without it lurching forward. I had the carburetor rebuilt last year, and it had this problem prior to rebuilding, and it still has the same problem. It is almost like it is hanging up on the high idle tang. If I bump the throttle, the high idle will drop down to where it should be, and many times, the engine will just die. Suggestions as to what to look for, or should I just send it out for rebuilding again? Other than that, it runs great, and there is no acceleration lag.

 

[55Brodie]

I wonder if the throttle shaft bore is worn and needs to be bushed.

 

[La Hot Rods]

I would look at the choke, make sure the fast idle cam is not hanging up.

 

[Jerry B]

Had the same problem with 409 dual four rear carb. Best I can remember it was either the accelerator pedal or carb linkage binding. Would sure do more trouble shooting before rebuilding again.

 

[Junky]

I have already checked the accelerator pedal for any binding, and the throttle cable also. I know it is in the carburetor, just not certain exactly where. The last thing that I want to do is to spend money on anything needlessly. I have never been one to throw parts at a problem hoping that it will solve the problem.

 

[4onthefloor]

I had the same problem and found there was slop where the throttle arm connects to the throttle shaft. Also take a look and see if the throttle blades are not fitting evenly in the venturi bores. I have had to loosen the 2 screws on each blade and realign Them.

 

[Jim Sullivan]

I had a similar problem a couple years ago. As mentioned above, it was the throttle pedal shaft bushing. Just a slight drag would cause the idle to hang at a couple hundred rpms too high, Drove me nuts. If you haven't already, try disconnecting the pedal linkage from the carb and see what happens.

 

[Junky]

Update... a friend came by this afternoon, and offered to stick his head under the hood. First I showed him how it was hanging up, and we removed the throttle linkage and the downshift linkage from the carburetor, and reattached the spring. With the engine cold, he could clearly see that the spring wasn't strong enough to pull the throttle back all the way. Then I started the engine, and allowed the engine to come up to operating temperature. Shut the engine down, and checked the throttle again, and it hadn't changed. It still wouldn't come back all the way. He methodically looked down the throat of the carburetor for any abnormalities, but none were visible, and the throttle closed completely. Started the engine again, and the throttle wouldn't close completely. Shut it down again, and upon further examination, he determined that with the engine running, the vacuum under the throttle plate was being held slightly open on the drivers side. He then kept snapping the throttle open and closed manually, and he believes that there might be a slight bur on the left throttle plate that is what the causing the problem. He believes that with time, this small bur will eventually resolve itself, and the problem will be gone. Suggested a stronger spring to overcome this. There is no wear in the throttle shaft, and the carburetor is functioning well otherwise. I am presently using a NOS GM spring. I am open to any and all suggestions that will help

 

[oldskydog]

I have a vague memory of a problem on the Corvette, probably 62, that required adding a second spring was a factory fix. I'll see if I can find the reference.