[Bronco2]

The large notch is 0 (tdc) Be sure to disconnect the timing connector wire before you try to set timing. If the emissions label is still under the hood it will give you timing instructions. Taking a piece of sandpaper to the timing indicator will make it much clearer. I think the timing connector on your truck is under the master cyl.,brown and black wire,2 pin weatherpack connector. It loops out of the wiring harness. About the IAC- the IAC is held open at all speeds-it stays open in case you have to hit the brakes hard,this avoids engine stall. Since you know where your IAC is,I assume you have a scan tool. Is your engine temp. in the 190 range? I don't know the emission specs in your area,so far we have avoided them where I live,but the more details the better.