I have a 78 CJ5 with the straight 6 258ci. I have heard of carburetor problems with these engines. What can I do to the stock one to make it run better? Or, what can I replace it with? I am new to the Jeep game, so I don't know alot about them. Any help would be appreciated.
1)The cheapest....rebuild your current carb. (It will be a recurring event though)
2)Cost about $150...replace with a motorcraft carb. (MC2100)
You will have to fabricate a throttle linkage and find a air cleaner housing to fit
3)Cost about $300...replace with a Weber carb. This is what I have done, and it runs like a champ. Everything is included here.
4)Put in Fuel Injection....cost between $1,500 and $2,500.
Depending upon your budget, I would swap the carb....if you are mechanically inclined, go with the Motorcraft.....if not, go with the Weber. (Best carb on the market).
It does sound like you have a carb problem but you should start by telling us more about your rig and what you have tried or how long you've owned it. Have you tried a tune up first? Does it have a catalytic converter? If so, it might be plugged. If you think the plugs and wires etc. are good and it doesn't have a cat. conv., you probably have a carb problem.
There are 3 excelent choices you have to replace the stock carb. . One is a Motorcraft 2100.
Two is a Weber 2bbl carb.,
Three is various fuel injection applications.
I have a Weber but may switch to the Motorcraft 2100 until I can afford the Mopar EFI. The Motorcraft is the cheepest fix at about $150 plus the manifold plate. The Weber is probably about $350 and up. The Mopar is in excess of $1500. These are ball park figures if YOU do the work yourself. Labor will cost you dearly. For instance, I know a place that will do the FI for $4000. You drive it in, then drive it out (after you plunk down your credit card).
2004 Rubicon, 6" lift, 35s, winch, hard top, full doors, bumpers, tire carrier and rock sliders.
Its completely stock, 60k miles, passed down to me from my grandfather. He only drove it when we got snow or ice, which doesn't happen very much in Texas. I've given it a tune-up and new batteries. It is also slipping out of 2nd gear. It does not have a catalytic converter on it.
Livin2learn - you must have been writing your post while I was writing mine. They say almost the exact same thing. If your post was there already, I would not have even posted. LOL
JMSCJ5 - if it's been sitting for a while, you may have bad gas in it, a gummed up carb., and or a sticky valve. As far as the tranny is concerned, I'd worry about getting it running right first, then tackle the transmission problem. What transmission does it have? 3 speed? granny 1st gear? etc.
2004 Rubicon, 6" lift, 35s, winch, hard top, full doors, bumpers, tire carrier and rock sliders.
livin2lern: I'm at the point of replacing my carb. on my '83 CJ-7. Other than the money issue, which carb should I get? The mc2100 or the Weber. Do they perform the same, or does on provide more power than the other. If I go the mc2100 route, what do I tell the auto parts guy exacty what I need?
before you spend the money on a new carb(which you dont even know for sure if that is your prob yet) try this.
Easy Fix for Jeep 258 Carter BBD Idle Problem
by Terry L. Howe
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 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.
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.
Thanks to Randy Peterson for posting this solution a few years back. I've used it on various Jeeps many times since.
Last modified Wednesday, 27-Jun-2001 11:45:24 EDT
this is the carb fix from JEEPTECH.COM
[COLOR=darkgreen]"character is doing the right thing even if nobody is looking"[/COLOR]
That is a great idea, except even after you clean out your venturi's it will be a chore you will have to perform every couple months. If you have the carter on there, you will be doing nothing but improvement by getting rid of it. Even if it ended up not being the problem (doubtful) you will still have a better performing carb.
With money aside, hands down, get the Weber. It is the easiest install and needs no adapters.
If you were on a strict budget, you could got the MC2100 route. On a performance basis, the two carbs supposedly perform about the same. With the MC2100 you will need a part from Mr Gasket and a new air cleaner assempbly.
You can get the carb itself from and auto parts store, along with the gasket. THe air cleaner assembly you will have to get from a junk yard.
go to www.jeepsunlimited.com and do a search. If it is not working, send a PM to toluan, and talk to him. He is a wiz with the Carter and he just did the MC2100 swap.
If you decide to go the Weber route, I would be more than happy to help ya out were I can.
You can probably find domeone to help you with the swap if you decide to go that route....I am 3.5 hours away in Austin, so any help I lend will be through e-mail.
Sometimes it is better if someone is there with you to see how your set-up is.....
The Weber swap isn't rocket science, especially on a pre-1983....without the computer, you should have an easy install. Either way though, it is about a two hour job (includes drinkin' beer and scratchin head a couple times). You could probably get it done in an hour if you had done it before.
Once again, good luck, don' hesitate to ask questions.
I did the drill out and it defn did help. As particles of **** and dirt get jammed in the teeny tiny factory holes on the venturi cluster.
That was before I did other things...
I replaced my fuel lines... that helped.
I did an ignition upgrade - and that made a huge difference... its a TFI coil you want and change the spark from 8000Volts to 30000Volts ..... needs a few parts but in the end it starts like a greyhound out of the trap and burns fuel alot hotter.
Then I stuffed it up - I was advised to go Weber Carb and did so ... big mistake... never idles very smoothly... every month the filter needs cleaning as it sucks in more crap than a very big crap sucker... if i had the choice over i would go back to a late model carter carb as thats what it was designed for.
Webers in my mind are not very good off road... and as i say need constant cleaning.