Throttle doesn’t want to return to idle

[DustyDave]

I have a 4-speed ‘Cuda (73). Every time I let off the gas, I have to goose it to get the idle to come down? The spring seems good enough?

 

[Challenger RTA]

cable or carb components wore and hanging up.

 

[tonysrt]

Remove throttle linkage and and loosen carb to move it above the manifold and see if it closes. Either no slack in throttle linkage or restriction in either gasket or manifold or bad carb. You do have a good return spring on the carb throttle? Is the choke completely off when engine is warm? What carb are we talking about?

 

[Chryco Psycho]

Sometimes the gaskt below the carb can interfere

 

[Xcudame]

If it's a Thermoquad (my favorite street carb), some times the primary throttle shaft holes oval out and can cause the blades to hang up.

 

[moparleo]

Disconnect the throttle cable and test. Is this a new problem out of the blue or has something been replaced or adjusted ?

 

[tonysrt]

He never said what carb is his problem.

 

[Coupe]

If the carb return spring is anchored too high, it won't pull all the way to idle. I had an Edelbrock with this problem. I drilled a hole, lower on the spring anchor, that fixed it.

 

[Cuda360-4]

I had this problem when my throttle cable became too worn. It was the original cable, so 50 years old. I replaced it and it kept doing the same thing, so it took several attempts to get the adjustment just right. Adjusted just the slightest bit too long or short made it catch and hold the throttle open.

 

[MoparCarGuy]

Some good advice in this thread but needs a more systematic approach to properly troubleshoot the problem. "Divide and conquer."
Possible problems...cable, return springs, carb throttle shaft, throttle blades, or throttle blades to carb gasket interference.

Remove the throttle cable from the throttle lever stud. Activate throttle by hand.
Does it move freely back to idle stop?
If so, inspect the cable to see if it moves freely in the cable sleeve. The cable could be frayed inside and sticking. Replace a bad cable by considering a Lokar throttle cable kit or purchase a new cable from Summit Racing (Pioneer brand is what they sell).
If not, inspect return springs. Yes, everyone should have two return springs. One inside the other.
If return springs are connected properly, move to inspecting the carburetor. Do you have a choke assembly? It could be sticking. You can remove it and retest the throttle actuation for binding.
Next, remove the carb from the intake manifold. Test throttle and look at your throttle blades and the throttle shaft.
Does it bind due to a worn shaft or blade interference at the carburetor base?
If not, were the throttle blades hitting an incorrect carburetor to intake manifold gasket? It happens. You would see marks or damage on the gasket if it interferes with the throttle blades.
Let us know what you find.