Thanks, that all looks more complicated than I thought it would be so I guess i'm even less mechanically inclined than I thought.
Not really so complicated. But it would help to know what carb you're running, as some automatic chokes (your carb does have an automatic choke, right??) work a little bit differently than others.
thegreatjustino did a "great" job of explaining the choke adjustment, and some steps to verify proper operation. Maybe it won't seem so complicated if I try to restate what thegreatjustino already said.
Basically there's two parts to setting up the automatic choke. The choke mechanism does two things. First, it provides a richer fuel mixture when the engine is cold, and second, it provides for a faster idle setting when first starting. The faster idle is like keeping your foot on the gas for a few minutes!!
On the passenger side of the carb, you should see a black cover, maybe 1 1/2" to 2" in diameter, and maybe 1/2" thick. This black cover does, in fact, cover the choke thermostatic spring. It's this spring which opens the choke plate as the engine (and that spring) warms up. The amount of enrichment the choke provides can be changed by rotating that black cover either clockwise or counter-clockwise. There should be notations on the cover which indicate the direction for richer or leaner. The cover is held in place by a metal ring with three screws. To adjust the amount of enrichment, loosen the three screws, turn the cover in the appropriate direction, and retighten the screws.
The second part of the adjustment is the Fast Idle adjustment. On the carb there is a stepped cam, as thegreatjustino mentioned, with a screw adjustment just over the cam. It may be on either side of the carb, depending on what carb you're running. As mentioned, warm up the engine, then rotate that cam until the adjustment screw is over the highest step on the cam. Adjust the screw to get between 1200 and 1500 RPM.
Also consider that the ckoke may be adjusted properly, but just not functioning correctly. When the Bronco is cold, before touching anything (like the gas peddle), remove the air cleaner to get a good look at the carb. Most likely, the choke plate will be open (verticle) or just partially closed. Actuate the throttle to full open, then back to full closed. What you should see, as the throttle is move to the full open position, is the choke plate will close more, and that fast idle (stepped) cam should rotate so that the highest step is under the adjustment screw.
Also do check out the metal tube that thegreatjustino mentioned. This tube should be there on the stock Motorcraft carb, but if you have some aftermarket/replacement carb, the choke may not have a provision for it. But, there should be some other mechanism to provide heat to the carb as the engine warms up. Some chokes are entirely electric. If you see an electrical connection on the choke mechanism, make sure there's a wire attached to it,and that wire is attached to an electrical source on the other end.
Hope I didn't step on anyones toes with this restatement. Sometimes it helps to hear the same thing said a different way.
