carb lean/ rich knob issue 53 pontiac chieftain

Hi guys. I'm new to the hamb and new to cl***ic cars and this car in particular. On my Carb there is a round metal knob that says lean with arrows pointing to the right that adjust the lean/ rich mixture. I tried to adjust this and it seems that this knob may be vacuum controlled or sealed cause it spins back into place. There 3 screws that hold the knob on, so I tried tightening them down a bit. After all this, the engine (straight 8) seemed to be running much better. We took the car out for about an hour. Coming off the interstate, it died, and we had trouble starting it. Upon inspection, the knob had loosened up and it seems one of the 3 screws may be stripped. What should I do about the screw and how do I get this knob adjusted properly. It was very tough to turn, as it wanted to spin the other way.

 

First as you don't know old cars get you a "Motor's" manual off ebay that covers the year of your car, will be the best thing you ever bought. Second that knob is the adjustment for the automatic choke. Normaly set once and then left alone. The reason it springs back is that it IS hooked up to a spring,the thermostatic choke spring.

 

Thanks John, manual on the way.

 

This must be some kind of accessory. Pontiacs did not come with such an adjuster.

 

Sorry Rusty but that is a stock thermostatic choke cover over the thermo spring. Some metal some black baklite plastic.

 

Sorry I misunderstood, thought it was some kind of carb adjustment.

 

So where is proper setting for the knob?

 

You need a day (or night) when the temperature is between 65 and 70 degrees F. THIS TEMPERATURE IS IMPORTANT!!!

On a cold engine:

(1) remove the air cleaner

(2) loosen the three (two on some models) retaining screws, but not sufficiently that the cover will fall out.

(3) rotate the throttle lever on the carburetor appoximately 1/2 of its travel and hold in this position.

(4) rotate the choke cover (round knob) toward the lean direction. The choke ****erfly should open. Now rotate the choke cover in the rich direction until the ****erfly just TOUCHES closed with zero tension.

(5) snug the retaining screws

(6) release the throttle

(7) replace the air cleaner

On the hole with the stripped thread, go to the hardware store and get a screw with the same thread, but one 1/4 inch longer. If this doesn't work, go to the auto parts store (with the screw for size) and purchase a "Heli-coil" kit.

Jon.

 

Thanks a TON Jon, give me a few days to get cracking on this and Ill post my progress. Thanks again!