Autolite 2100 Idle Adjustment

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pwstark

New member
I recently rebuilt my Autolite 2100 which sets on top of a 292 (64 F100) and is idling at 1,350 rpms. Adjusting the fuel/air screw doesn't seem to change the idle. I sprayed carb cleaner around the carburetor to search for vacuum leaks but didn't find any. Anyone have any ideas?
 
Make sure the throttle isn't stuck or the linkage isn't getting hung up anyplace .
If you make the fuel/air adjustments and nothing happens then it sounds like the carb is gunked up inside .
Maybe it's best to just do a complete rebuild . They are easy to do !

Jim
 
ive had the throttle plates hit the ports on the intake manifold and hold them open, if thats the problem you will have to put a spacer under the carb on top of the manifold
 
If you had the throttle plates out, they may not be set properly and not closing completely.
Detatch the pedal link and back off the idle speed screw all the way, go from there to set idle,,,make sure you have a good gasket seal at the base.
 
I have done a complete rebuild and did have the throttle plates out. They seemed to go back in and seal properly.
 
Like scrapiron said, the plates may not be in perfect alignment with the bores. That is the probable cause from my angle. Take the carb off, look at the bottom with idle screw backed all the way off, hold up to sunlight, and no light should be seen around perimeter. The fix is simply to take out the plates and reinstall properly.
 
Try something simple and basic first. With the choke plate completely opened, make sure the fast idle cam isn't sticking (on the passenger's side of carb) and staying on one of the steps for the cold speed adj. screw to hit. Should have a fast idle cam whether it's an auto or manual choke. If you verify the cam isn't on a step to increase the speed, then back off the warm idle speed screw (on the drivers side of the carb). If still idling too fast and your sure the throttle plates were re-installed correctly, then I would guess you have a vacuum leak at the carb base, or maybe the PCV hose has no PCV valve in it, causing a major vacuum leak. Possible the power brake booster is leaking too if equipped with power brakes.
 
Thanks Scrapiron, I took the carb off and seated the throttle plates and that took care of my problem with the high idle. Now, when I adjust the air/fuel mixture screws, it doesn't affect the idle. They are set at 1 1/2 turns out. Do these need to be replaced?
 
What rpms is the carb set at when you try to make the adjustments ? If the idle is to high , it's much harder to get the adjustments to work for you .
By some chance , do you have a vacuum gauge ? That will be the best way to set the fuel mixtures unless you have a very good ear and feel for the idle of an engine .
With the engine fully warmed up it should idle around 550 to 650 rpms depending on trans you have and then try to make your adjustments from there .
Also make sure your timing is set first before trying to adjust the fuel/air mixtures .

Jim
 
The idle mixture screws do not directly affect the speed, per se,,idle will stumble when either to far in or out. 1 1/2 turns out should be a good starting point,,,,adjust to get the smoothest idle,,,then adjust the linkage speed screw for proper idle if neccessary.
As said , a vacuum gauge can be used to help, and to adjust timeing by turning the distributer, vacuum should be 19 in. or better,,,,.
Hope this helps.
 
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