Hello All - Here's something - newly rebuilt Qjet, dialed in the mixture screws to what I think is correct because she idles better than ever. However, when I turn off car, she shudders like she wants to stay running. Go to restart and she won't unless I hold open butterfly. Ideas?

Thank you!

sounds like the spring on your plunger is sticking.

Check the idle speed.  When it's too fast it will shudder and sometimes diesel when shutting off.   The choke plate should be fully open when the car is warm.  If it is shutting that would cause a very fast idle and tend to flood the car.  You may need to adjust the choke coil.  New, the coil will have a dot on the outer diameter of the plastic housing.  That lines up with the notch on the choke housing.  setting just slightly rich, one or two notches, usually works best and prevents mid range hesitation.

Thanks for the feedback!

You know, my choke valve is always open when car is cold.  Isn't it supposed to be CLOSED when cold and open as the car warms up?

I'd also like to confirm that when I attempt to adjust choke coil, turning counter clock wise = run lean and turning clock wise = run rich.

Jason, you are correct on #1 - cold = closed. #2 is the opposite on the automatic (electric) choke coil - clockwise is lean, counter clockwise is rich. Good luck !!

If you have an A/C equipped car, there should be an idle stop solenoid which is used to set the idle speed.  When the key is turned off, the solenoid allows the throttle to close completely preventing dieseling.

Jason...is this the original carb for the car, or a replacement? Original carb would NOT have the black plastic choke cover on it, afaik. The choke is controlled by a coil mounted in the intake manifold that heats up and opens the carb.
If your carb has a plastic choke cover, you need to determine if it is electric, or heat activated. Electric choke would have a small blade tye terminal on the side of it. Heat coil would have a fitting towards the bottom for a tube that would run thru a loop either in the exhaust manifold, or the EGR crossover port in the intake. Let's determine what ya have first, then see if we can get it all adjusted properly.
And yes, you should have an idle stop solenoid, A/C or not.


|UPDATED|7/27/2015 10:20:38 AM (AZT)|/UPDATED|

I have an original QuadraJet, recently rebuilt, so it does not have the black housing.  It has the heated coil for choke.  Haven't experienced this "dieseling" before...that shake/shudder/wanting to stay on when turning off after a long drive.

From videos I've seen online, people bend the linkage going into the (I believe) coil lever...bend it just right to keep the choke closed when cold. 

Yep, I got confused with my old 68 GTO (which I no longer own but wished I did) that had one because it had A/C. It was designed to keep the engine from dying when you turned on the air conditioner. I now remember that my '73 had an idle stop solenoid on it without A/C.  When I added A/C, I rewired the idle stop solenoid so that it was activated only when the compressor was on. Did this for the same reason that they had done it on the GTO.
 

Thank you, 73Shark.  I would like to have the GTO, too! 

Are you saying that something with the idle stop solenoid might be off, that it's something I should look into?  Anything in particular I should be looking for?

Thank you!