Why won't my Bronco run?

You might have a weak spark. Pull a wire off a plug and hold it near the block while someone cranks the engine. The spark should go about a 1/4". If you have to hold it really close then you have weak spark. Check the resistances of your coil and make sure it's not bad. I would get a Pertronix coil to be sure. I would also pull the spark plugs and see if they're fouled or not, check the gap too. You might also check the choke erfly on your carb. It should be fully closed when the car is cold with light spring tension (after you push the pedal once to reset it). Make sure it opens smoothy (push it with your finger). As soon as you start the engine it should open up a little. If you have to put your foot all the way down (to dechoke) it might be too tight or stuck so that it isn't opening. Your timing might be really goofy too, but less likely. Hope this helps!