1986 F150 4.9l I6 with smog compoments removed. Its the single barrel stock carb. Need help with an adjustment. I have searched this site, Google, and the rest of the internet for 4 hours with no clear cut way. I messed up earlier and went to messing with a carb for a rough idle.. afterwards is when I found the vac leak but by then the damage had already been done.
3 screws. 2 of em are on drivers side of carb. one sitting on high left and other sitting on low right. One is for regular idle and the other for cold idle ( dont know which). 3rd is on pass side and I believe its a Fuel mixture screw.
The Choke is full closed then cold and opens up as it gets warmer.

Ok... So. in what order of these 3 screws do I "tweak" for best adjustment by ear? Nope. I dont have a vacuum gauge and have no clue how to use one. There any easy way to tell if its Running rich? Lean?
Thanks for the response in advance.

 

Well since your carb is computer controlled, this could be tough. Unless of course you have a Duraspark setup. How bad is it now??

If you look behind the carb there should be a electrical solenoid behind the carb. That thing controls the carbs idle speed and controls how fast the butterfly closes when letting off of the gas. Every time you turn off the engine, that solenoid retracts it plunger so the carbs throttle will be completely closed or closed with just a little gap. Also you have a solenoid on the side of the carb that controls the mixture during idle via "air" and other conditions also via "fuel flow" i think. So you have two things the ECM will be controlling.

One of those two screws you speak of rests against a "cam" The little plastic thing that lines up with one of those screws. The other screw rests against the carb itself. That screw that rests against the carb is the one that controls your base idle speed. The other is your cold idle speed. I have read on here that people adjust it to where the fast idle is about 300 rpms above your base idle. After you hop in the truck, press the gas pedal once before the days start up, and your choke should then be set. It should then be on the high step of the cam. Then after you start it, adjust that screw until you get a fast idle you like.

Now with your warm motor, turn off engine. Unplug the the solenoid behind the carb, and the one mounted to the carb itself. It goes up and down with two wires. Be easy with the connectors because they now have some age on them. You can also hope the connectors themselves are clean because some that may be corroded when you unplug them may not work when you plug them back in, unless cleaned which I have never done.

I just reread what you put, and you wanted to know what order. I would adjust the screw setting against the cam first. Then the mixture screw Next the base idle screw. Remember where you mixture screw is now. You may have to bump up the idle speed or lower it depending on what the engine does. After you adjust the mixture screw, open the throttle momentarily to see where the idle stabilizes at. I said mixture screw before idle screw because it may be close to where it needs to be. After you achieve a good idle, you may or may not need to turn the mixture screw in a little or out a little because I am not sure what mixture the ECM aims for at idle. After you set your idle by ear to get close to the ECM's idles speed which is gonna be hard since you cant see what the rpms are. Turn the idle speed screw out a little to lower your idle because your ECM is gonna want to control it. Your carb has preset mixture and idles screw, then the ECM further controls its.

Then plug your stuff back in. Reset the computer, by unhooking the negative battery cable for about 10 minutes. Thats about all I can add cause I did it this way because all my stuff didnt work when i bought it.

I do remember reading a post by someone concerning adjusting these carbs but It is probably back between about 3 or 4 pages maybe all the way back to 7 or 8 pages. And that is just ball parking it with how fast the Bullnose forum goes. If anyone reading this wants to add to this or correct it, please do. Like I said, I did mine this way because all my stuff was unplugged and other stuff didnt work at the time.

Thats about all I can say and good luck with it.

 

blue84f250 provided well thought information, but there is one point that will impact what he said... your first sentence, OLDBLUE1986, states that the smog components have been removed. 1984-1986 4.9L [49 state models] came equipped with what is known as a feedback system [carburetor, distributor, sensors and computer]. With any of the original emmissions equipment removed, the computer will lock everything [carburetor and timing] in the "safe" or "limp home" mode. This means the carburetor will be rich and the timing locked @ 10 degrees BTDC... safe for the engine, but terrible for performance and fuel economy.

Look at your carburetor and see if it is still the original computer controlled one [hint... does it have electrical wires other than the single one going to the choke heater?] Next, look at the base of the distributor... does it have an electrical connector at the base [usually grey in color]? Or, does it have a vacuum cannister with a rubber hose going back to the carburetor?

Get back to us and we will go from there.

 

Today Choke was shut completely when i pulled the air cleaner. It cranked But doesnt run too good. Choke came open pretty quick compared to what it did before it seems.
BLue84f250 and 1986F150six its one single wire going into the back of the carb where what im hearing is for the choke, and the distributor has the gray electrical housing with plug in it. This morning I got some vacuum hose "nipples" (whatever they are called) to plug the unused smog port and checked the rest of them which seemed to be in good shape. When i pulled off what I had on it, then some gas came out of the vaccum port from where it was flooding yesterday.
I havent messed with the actual carb anymore til i get a better idea of what Im doing.
Thanks for the help guys! This forum is pretty awesome. If we can get this sorted out on here then im sure it will help others who needs it as they find it in a search.