1985 cj7 carb which screw is which?

Call Howell and buy the throttle body fuel injection conversion. You'll never turn another screw on the carb. Best $1200 I ever spent on my 87. All of the vacuum lines are eliminated.
 
Limpinlobster said:
Believe me I want to, but this is what I got for now.
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The idle jet screws are located under the fuel line. One left and right. It takes a skinny long screw driver to access. There is no main jet adjustment. The carb is a computer controlled piece of garbage. You pretty much have to rebuild the carb if it is running like crap. Buy a chilton's manual and closely follow the directions.

My yj would barely run over 4000 feet. Fuel injection was the only solution. If you read the chilton book, there is a way to trigger the computer for high altitude, but it never worked for me.

These systems are really terrible because of the amount of vacuum lines needed to control complex systems to reduce emissions.

Believe me. The cheapest thing you can do is buy fuel injection. I can drive my yj right up to the smog station and pass with no problems. It cost about $1500 each of the two previous smogs before fuel injection.

Sorry. That was a lot, but I've had my 87 for 7 years and did nothing but fight that carb.
 
MarkW13 said:
The idle jet screws are located under the fuel line. One left and right. It takes a skinny long screw driver to access. There is no main jet adjustment. The carb is a computer controlled piece of garbage. You pretty much have to rebuild the carb if it is running like crap. Buy a chilton's manual and closely follow the directions.

My yj would barely run over 4000 feet. Fuel injection was the only solution. If you read the chilton book, there is a way to trigger the computer for high altitude, but it never worked for me.

These systems are really terrible because of the amount of vacuum lines needed to control complex systems to reduce emissions.

Believe me. The cheapest thing you can do is buy fuel injection. I can drive my yj right up to the smog station and pass with no problems. It cost about $1500 each of the two previous smogs before fuel injection.

Sorry. That was a lot, but I've had my 87 for 7 years and did nothing but fight that carb.
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This ^^^. Back in the day, I had done what was known as a Nutter bypass but later found out that it wouldn't pass CA smog laws. I eventually upgraded to a Howell TBI. If you don't have smog to deal with, I would recommend rebuilding the carb and bypassing the computer as well.
 
MarkW13 said:
The idle jet screws are located under the fuel line. One left and right. It takes a skinny long screw driver to access. There is no main jet adjustment. The carb is a computer controlled piece of garbage. You pretty much have to rebuild the carb if it is running like crap. Buy a chilton's manual and closely follow the directions. My yj would barely run over 4000 feet. Fuel injection was the only solution. If you read the chilton book, there is a way to trigger the computer for high altitude, but it never worked for me. These systems are really terrible because of the amount of vacuum lines needed to control complex systems to reduce emissions. Believe me. The cheapest thing you can do is buy fuel injection. I can drive my yj right up to the smog station and pass with no problems. It cost about $1500 each of the two previous smogs before fuel injection. Sorry. That was a lot, but I've had my 87 for 7 years and did nothing but fight that carb.
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O dang, I actually just had the top end rebuilt, and the carb as well. I had the carb tuned for a while but tried to fine tune it and jacked it all up again. That day I spent about three hours turning screws, and driving, then pulling over and turning more screws until I got it back to normal. I'm going to take your advice and put some money aside for the TBI. I definitely want to go long distance and have it be reliable wherever I go. thanks again.
 
wayoflife said:
This ^^^. Back in the day, I had done what was known as a Nutter bypass but later found out that it wouldn't pass CA smog laws. I eventually upgraded to a Howell TBI. If you don't have smog to deal with, I would recommend rebuilding the carb and bypassing the computer as well.
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my buddy has a YJ and he did the nutter bypass. It works good for him, but he says he wish he had fuel injection to. Smog was holding me back from doing that as well. But, going to go with the TBI as you say and as the other person says. I plan on going everywhere with that CJ. Hopefully on a trip with you guys one day.
 
I also bought an hei distributor which really helped because the factory ignition module was pretty complicated. If you get the kit and have any problems let me know. It takes the better part of 2 days to install and you will need to be very familiar with the wiring diagram for your model jeep.
 
Glad to see another CJ. I installed a Howell on my 79 and have never been happier. It really is unreal the difference in performance.


While we are all scouring Google for you, what symptom are you having?

Poor idle may be blocked idle tubes as Google search would have it. Here is a link to correct this. http://www.jeeptech.com/engine/carter.html. Don't typically like to link to other sites for technical assistance so here is the article
The Jeep 258 (4.2L) I6 isn't a power house, but it has gobs of low RPM torque that makes it a great engine off-road. The most common problem I see with the engine is it's inability to idle. Between the 258 in my '81 CJ-7 and a couple friends that have 258 equipped Wranglers, I have fixed this problem half a dozen times and the cause of the problem has always been the same. The problem has always been caused by clogged idle tubes that cause fuel to drip out of the venturis and make the Jeep run rich at idle. Fixing the problem is relatively easy and once you get past this problem, you will get much more enjoyment from the 258 and the Carter BBD carburetor.

The Carter BBD is a two barrel carburetor that was available on late 70s to late 80s Jeeps with the 4.2L engine. There are two variations of the carburetor, one is computer controlled and has a stepper motor on the back side. The computer controlled version was used after 1981. Other than that, the two versions are the same although it seems the stepper motor version is a bit more troublesome.

The Symptoms

The symptoms of the problem include stumbling and sputtering at idle. In advanced cases, the Jeep will stall at every stop sign and will only run at high RPMs. Gas mileage will suffer since fuel will just be sloshing out at idle. Sometimes the idle will be turned up to a high RPM to avoid the problem. Typically, the Jeep will run fine at higher RPMs (unless there are also other problems.)
For a sure diagnosis, park the Jeep with the engine off and remove the air cleaner cover. There should be a plate over the throat of the carb, the choke plate. If you open the choke plate you should be able to see down the throat of the carb and you should see two screws with holes in the middle of them. Next to them are two passages with a nozzle in the middle of each. This thing is known as the venturi, when air passes by, fuel is supposed to be drawn out through the nozzles. If the idle tubes are clogged fuel will drip from those nozzles during idle.

In order to see if fuel drips from the nozzles at idle, you must start your Jeep with the air cleaner cover off and look down the throat of the carb. The Jeep Technical Service Manual recommends that, when you do this, you cover the air cleaner with a piece of plexiglass since the engine can backfire through the carb and a flame can shoot out. Since I am reckless and like living dangerously, I never do this.

After you have chosen the wise or foolish path, start your Jeep and open the choke plate. If your idle tubes are badly clogged, you will see fuel dripping from the nozzles at idle (if your Jeep will idle at all.) If you don't see fuel dripping, but your idle is still poor, open the throttle a bit with your hand or have a friend hit the accelerator. You should see two even streams of fuel and no dripping from the nozzles. Any dripping means clogged idle tubes.

While you are doing this, make sure you don't put your hand or anything else into rotating parts like the fan. Keep your tie away from that thing (some people just want to look good all the time.) Same goes if you are a "long hair, freaky" Tesla type. All joking aside, I've heard some bad stories.

Carter BBD Apart
The Solution

Neither removal of the carburetor nor a complete rebuild is necessary to fix the problem. To fix the problem, start with you Jeep off and parked securely:
Remove the air cleaner cover and air cleaner. You may need to remove a few hoses and wires to get the air cleaner out of the way. Make sure you tag them all so you can put them back in the right spot. It's often easiest not to remove the heater hose that goes to the exhaust manifold, if you have one.
Remove hoop that holds air cleaner.
Remove the two screws holding the choke plate with a 3/16" socket or small flat blade screw driver depending on what screws you have holding it. Be careful not to drop the screws down the manifold unless you enjoy fishing. Remove the choke plate.
If your carb has one, remove the plate on the side that covers the choke linkage so you can access the screw holding the choke rod. It may be necessary to drill out a rivet to get it free.
Remove the little snap ring and screw (1/4" socket) that holds the rod that holds the choke plate and remove the rod. A screw driver will normally push off the snap ring.
Remove the two screws with holes in the middle of them and carefully remove the venturi cluster with the two little gaskets. There should be two idle pickup tubes pushed into the venturi sticking out of the bottom. If they have fallen out, that could cause your idle problem.
Blast the venturi and inside of carb with lots of carb cleaner. Be sure not to dislodge the check ball in the center.
With a long thin pin or piece of piano wire, make sure the idle tubes and nozzles are clear. After you have run them through, spray with more carb cleaner.
Put the cleaned out venturi cluster back with the two gaskets and two screws.
Replace the choke rod with snap ring and screw and replace the choke plate. Make sure all the screws are tight that hold together the carb body at this time. Often the screws will loosen up and dirt will be sucked into the carb.
Replace the plate covering the choke linkage with a sheet metal screw, or leave it off.
Replace the air cleaner.
Smooth idle should have returned after this simple process. If you still have idle problems and don't have any dripping, make sure all the vacuum hoses are hooked up and in good shape. Also check for leaks around the intake manifold or a loose carburetor.
To avoid repeated clogged idle tubes, drill out the idle tubes to 0.032". This will greatly reduce the frequency of clogging and it is a procedure that was actually recommended by Jeep for a while.

An alternative to removing the choke plate and all is to just remove the top of the carburetor. The advantage of this approach is you can make sure there isn't a lot of junk in the bowls, you can check your float adjustment, etc. It also may help if you have power brakes because the master cylinder may be in the way of getting the choke rod out.

Contributor

Thanks to Randy Peterson for posting this solution a few years back. I've used it on various Jeeps many times since.
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I will definitely take you up on that if I run into problems. And originally I had it dialed in, but tried to get a little more out of it. Jacked it all up, but got it running good again. I just had it rebuilt, so it was just fine tuning it. Of course that will all be a thing of the past soon.
 
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