I have an 86 f150 300 with e5te carb(tag is gone and that is all that I remember I think)that won't pass an emmision test. I have taken it to a mechanic who said there are no vacuum leaks and the carb needs to be rebuilt. (I rebuilt it six months ago) I rebuilt it again making sure nothing clogged up, all gaskets in place and adjustments as best I could. There is only one needle valve adjustment...The mechanic claimed he adjusted
this because it is running lean(too much air?) but it is set at two and a quarter turns out which is where I had set it as this is where it was six months ago. In rebuilding this I fould nothing wrong all passages open and clean. Engine vacuum at idle 700 rpm is 18 mmhg up 2mmhg after finding choke pull down leak. Is this a good number? Are there specs for the amount of vac engine should be pulling at a specific rpm? vac doesn't bounce around as much so I feel that most of the vac leaks are found. How do you adjust the thottle position sensor? Is the idle adjusting needle used for a rich/ lean adjustment? If it is how can I determine if the engine is running rich or lean or ok other than listening for smooth running? What else should I look for so this can pass emmisions?" There are other things that I've check but have not included here.