tuning a motorcrap 4bbl

[Bryan]

Just bought another Wagoneer, a 1981 with a 4 bbl carb. it would not idle below 2000 rpm (it has a tach) so I started tinkering with the carb. the idle adjustment is all the way out. there are two screws in the front base of the carb that I started screwing in that eventually dropped the idle down to where it should be. It runs a tad bit rough but I still need to put in new plugs & wires so that may fix it. Are there any other adjustments on this carb? I know its a motorcraft but not sure which model (It does have a non functioning electronic choke) as this is not the stock setup. Thanks!

[Michael]

There are a few things that can cause over idle. Vaccum leaks, vaccum lines connected wrong or plugged, mixture, and timing. Sounds like you leaned out the mixture to get it to idle down. It will run rough then. I would lean towards checking your timing making sure it is not way over advanced, and checking and make sure any vaccum lines are in there correct spots or not plugged. Something else must be causing it because with the idle all the way out the mixture should drop it near dieing. What is the idle now?

[Bryan]

Michael, it is idleing at 600 now in Park or Neutral, and 450 when in gear. I will check the timing tonight, and it definitly needs to have the vacuum lines replaced, they are visibly cracked or broken in several places. refresh my memory on checking the timing again if you would please! Thanks, I'm not much of a mechanic but this new one is just a project so I dont really care if I screw something up, it's' a great chance for me to learn hands-on!!

[Michael]

Do you have a timing light? If so hook that up and point to the timing indicator near the pasenger side on the balancer. Are you with me? You will first need to take some white out(liquid paper) and mark the balancer where the grove is on it. You will see a mark or groove. This indicates tdc. Then take you light and point it at the balancer. Each mark on the indicator or arrow, is 5 degrees. If it is jumping all over the place you will have to stop because you cannot get an accurate reading that way.
Loosen the bold at the distributor. Just slightly so you can turn the distributor. It should not take much.Turn your wag on and point the light to the balancer again while turning the distributor. Turning left will advance and right will retard. Turn what ever way to get 12dbtdc or what ever your tag under your hood says. I am so much better showing you. I hope this makes sense. Maybe someone else could explain better...LOL

On the other note... No light. loosen the distributor and start the rig. Listen carefully. Advance or retard till it smooths out. I do not suggest that because mine sounds best way too advanced. Hope this helps.

[Chero77]

You probably have the Motorcraft 4350. I've run this carb with and without emissions and it works well either way. The carb gives good performance, handles steep angles quite well, and if you keep out of the secondaries, gas milage is not too bad.

Anyway, the 4350 is easy to rebuild and as long as you keep the engine relatively stock it should work fine. Remember that this is an emmissions carb so the calibration is quite lean. You can change this a little by setting the vaccum piston gap as narrow as possible, i.e., to the tight side of the tolerence range. What this does is hold the tapered metering rods a little higher in the main jets, so the primary side supplies a slightly richer mixture. There is no practical way of changing the mixture on the secondary side.

If you are going to do away with emissions and want to squeeze every ounce of power possible out of your engine, you will want to run a richer mixture than can be obtained with the 4350. In that case, your choices basically come down to Carter/Edelbrock AFB's, or a Holley.