autolight 4100

[Larry Jones]

My engine was running great the other day. I noticed that the top screws on top of the carb were loose so I went around and tightened all the screws on top and in front of the carb and behind also that were loose. PLus I sprayed carb cleaner with the engine off and let set in the bowl for a few minutes and then proceded to start the car up. When driving it now its smooth but idling its somewhat rough. I didnt adjust any of the screws down inside the carb at all. What could be the problem. It seems when idling it wants to stall out. Thanks Larry.

[simplyconnected]

...I went around and tightened all the screws on top and in front of the carb... ...idling its somewhat rough... ...It seems when idling it wants to stall out. Thanks Larry.

Did you tighten the small brass screws in the front? Those are for idle adjustment.

[Larry Jones]

engine wants to stall out

Goodafternoon. I didnt touch the idle mixture screw at all Just the front on top of the carb and behind it up to then ever thing was OK. When at a idle the wheel shakes a little bit. I ubdid the fuel line and cleaned the small filter and reattached everything back together again. Next Iam going to check the plugs and see if any cracks out there. How would you adjust the carb idle screw anyway. Thanks Larry

[Larry Jones]

Idle adjust screws

How do you reset those two screws to get a smooth idle in the drive position. When Iam at a light the car wants to stall out but when I go it runs smoothly. Do you screw them in all the way and back them out with a tach when the engine is running smooth in the drive position. Thanks Larry

[Rigormortor]

How do you reset those two screws to get a smooth idle in the drive position. When Iam at a light the car wants to stall out but when I go it runs smoothly. Do you screw them in all the way and back them out with a tach when the engine is running smooth in the drive position. Thanks Larry

A couple ways to adjust the rich/lean mixture screws.... the best is too hook up a vacuum gauge and adjust for maximum vacuum. A faster easy way is to turn the screw in till the engine runs rough, then back out the screw till the engine runs smooth. Do both screws this way.

[simplyconnected]

Good evening Dave.

My 4100 carb shows two idle mixture screws in front of the carb. on page 3-14 figure 13 it shows only one of these screws. What do these two screws suppose to accomplish. Does one control the primary throttle plate and the second one the secondary plates. Can I unscrew each one at a time and remove one without any problem. I was told too screw in each one all the way and then back out two and half turns. Could you spray gumout through each opening also. Plus why does it rough idle even if there is possibly dirt particle somewhere and doesnt affect it at higher speeds at all. Would the culprit be in the secondary as opposed to the primary maybe thats why when I get going no problem but when idling everything shakes. Just a guest. Larry

Larry, the adjustment screws only affect your idle; they are only on the primary side of your carb. They can unscrew, so don't lose the springs.

Follow the instructions in your Shop Manual or use the vacuum method for timing and idle adjustment. Leave the shifter in PARK when you tune the carb.

I would rather post my answers on the forum for everyone to see, instead of using 'private message'. That way, if someone has a better method or I am wrong, someone will catch it right away. That's what the forum is all about; all of us helping each other. - Dave

[novanutcase]

Larry,

As Simply stated it would be best to tune the carb per the manual but I've found that if you want to at least get it close to turn both idle screws in until they just start to bottom out. DO NOT TIGHTEN THEM!!!

Then I turn them out a turn and a half. From their you can fine tune them but I'm usually pretty close doing it that way.

BTW make sure you adjust your main idle screw first before you do the ones in front of your carb.

John