84 CJ-7 Carb Help

Just got this last sat and only had time to get it off the trailer and head back to work. It is an 84 with a 258 i-6, with ecu on it.
Some Po has hacked up all the smog and ecu parts to the carb. It runs ok but not correctly. Here is where I need your help. Oklahoma does not require yearly exams of your cars or trucks so removing smog parts is ok.

1. What all does the ecu control?

2. Can I remove the ecu and smog parts and convert this to just pre ecu setup.

3. Can I convert the stock carter carb to a manual choke.

I want do do this in a correct manor, the jeep only has 3 issues,the carb, leaky valve cover, and some blowby, everything else in good shape.

Thanks in advance for any help. Jim

 

well, in a nutshell:

The microprocessor (MCU) controls a lot of functions on/of the engine.
Inputs from coolant temp, oxygen sensor, vacuum sensors, knock sensor, etc etc, help the MCU control and maintain the fuel mixture via the stepper motor on the rear of the BBD carb. The MCU can also control ignition timing, EGR response and so on and so forth.

All of this is required to maintain what's to be perceived as the optimum air/fuel ratio while idling and driving down the road.
For beginners not familiar with the system, or new owners like yourself, it can seem overwhelming; it may be in your best interest where, as the law allows, to just removed damaged, hacked up, or inyour case, inoperative components.
Switching to a non computer controlled carb will help (others will suggest a carb conversion of some type and size) but your still left with wiring to deal with.
I would suggest the factory service manual, or another reliable source of information, prior to you just snipping wires and unplugging components.
Your vehicle should not be air pump equipped if I recall, but you do have upstream/downstream air tubes and check valves to contend with, that should meet and connect at the factory air cleaner base, unless the PO removed all that.
Just study up before you jump in.

So now, what's wrong or missing with your system?

 

I believe the ECU controls the mixture (idle jet? idle air?) stepper motor. The usual fix for these is called the "Nutter bypass" (after John Nutter, who is/was a member here). Look here - http://www.4x4wire.com/jeep/tech/electrical/jn-ignition99/ and Google "Nutter bypass" for a lot more discussion.

Yes, I believe you can eliminate the ECU under the dash if it has been bypassed. The other ECU, in the engine compartment, is for your electronic ignition, and must not be removed.

 

So now, what's wrong or missing with your system?[/QUOTE]

I did not have time to take pics and it will be a few days I am riding out the storm on the rig site.
From my short memory:
1.The two larger hoses off of the back of the aircleaner are cut & open.
2.Several of the smaller vac hoses are cracked or cut.
3. The hoses to the charcoal pot on drivers side and vac pot on passenger side are gone.
4.Most of the 2 pin plugs on or around the carb are melted or unplugged.
5. The vac to wire gizmo behind the carb that is y'd off of the pcv is oily. What is it's purpose?
6. The temp guage sending unit is broken, and the fast idle adjusment wires are bad or missing.
7. The choke does not work.
8. Once warmed up the engine idles ok but if you take the airbreather cover off it will start to run very poorly to the point of dying.

This is the short list for the carb and engine.

One other thing I forgot is the jeep road walks. There seems to be some play in the steering box, timgr does the post you put up a couple of days ago on the steering box adjustment apply to this one it is a manual non power steering box?

 

Partly. The adjustment procedure is roughly the same, and the TSM covers it in the same chapter. Adjustment is done on the bench using an inch-lb torque wrench. Parts for the power steering gears are much easier to find than for the manual gears.

If you want to take it apart, there are a more parts in the power steering gear. I've rebuilt the manual gears (actually Ford manual gears, but they are the same design as the Saginaw manual gears), but I have not rebuilt a power steering gear.

 

I think Tim's suggestion then for the Nutter will probably be your best bet then.
Sound's like there isn't much to salvage. Might keep the MCU, it might be good.

 

GM HEI ignition and a MC 2100, problems solved, well 50% of them any way.

 

Found this on pirate do you agree with 1.08 sizing?

Also what make and model gm hei do I look for?
http://www.pirate4x4.com/forum/showthread.php?t=131514

 

Yup, the 1.08. Quite a few choices for the HEI, can't really recommend one over another, I built my own. DUI make a good one, there's a couple more but can't remember who makes them. Generally anything made in China are the ones you'd want to steer clear of.

 

What hei did you start with I plan getting what I need from the local salvage yard?

 

250 in-line 6 Chevy would be the most common, 292 not so much. There's two styles, the one piece coil in cap or remote coil style, either will do as far as the distributor itself, the two caps are interchangeable. You'd just need the rotor to match whichever you go with. Grab the connectors too.

 

Thanks everyone for your input, I like the simple fix Pack Rat suggested, should be the least expensive way to go.

 

I did the MC2100 conversion on my J10, and it works fine. I used a 1.08" 2100 from a mid-70s Cherokee with a 360. The Jeep carbs '73-on have a float damper spring (desirable) that the Ford carbs do not. Every rebuilt Jeep 2100 I've seen has lost its damper spring, so you'll need to find an unmolested Jeep carb if you want the damper spring.

Otherwise, the main difference is that the later carbs have a 2-stage power valve and leaner jetting. You can tell the 2-stage valve carbs by the depth of the power valve cover (1-stage is about 1/4" and 2-stage 3/4"). The 2-stage valve is about 5 times the cost of the 1-stage valve, so the 2-stage carbs cost more to rebuild.

Later Jeep 2150s (also acceptable) have an altitude compensator that's effective if it works.

Here are some pictures of my conversion:




I used a Transdapt base adapter - I think you have your choice of Transdapt or Mr. Gasket brand - Mr. Gasket has a good description of their adapters http://go.mrgasket.com/pdf/carb_fuel_sys_acc.pdf - you need #1937?

I was not impressed with the fit of the Transdapt adapter. It worked, but used cheesy hardware and did not line up very well (not very accurate).

I made a little bracket that converts the rear-pull linkage on the 2100 to the down-pull used by the BBD. You also need to make a new link from the engine to the carburetor. I just used all-thread and some ball joints I got from Summit - I had the ball stud from some other project. You could also use some small Heim joints from McMaster-Carr and others. A little ingenuity is needed, but it's not hard. (The shoe lace has since been replaced by a bracket).

Installing a manual choke is simple using a Dorman kit from your FLAPS:




There's a guy on eBay that sells a complete kit with all this stuff - just bolt on. http://cgi.ebay.com/ebaymotors/Moto...r_Truck_Parts_Accessories&hash=item4aa83acd9b - Good price for what you get, IMO.

Re the HEI, why the heck would you ever want to convert an '84 CJ to HEI? You already have an excellent electronic distributor that works on exactly the same principle as the HEI. No significant difference... actually the advance curve of the factory distributor is better for your engine than the HEI. And IMO, the factory Duraspark distributor is a significantly better design than the big cap HEI. Just do the TFI/"Team Rush" upgrade and be proud. Get a hot coil or a MSD capacitor discharge module if you want some more spark voltage.

Look here - this is the best "complete" write-up that I know of. http://www.jeepforum.com/forum/f8/i-6-teamrush-upgrade-definitive-669495/

 

1- Not really but I'd probably go with an early/mid 70's version.
2- - Mr.Gasket #1937 available at Summit, Jegs, Advance, Auto Zone, O'Reilly etc.
3- Not sure if they're available separately. I know there's a guy on eBay that sells the carb and I think it comes with a bunch of linkage. Shouldn't be hard to put something together.
4- Yes you will need to replace the gear. Found this one on eBay-4.2 HEI Gear, I know there's some others out there that sell them too. I think I ended up using one off a Prestolite V8, only because I had one sitting around and that's about all Prestolite distributors are good for.

 

Re the HEI, why the heck would you ever want to convert an '84 CJ to HEI? You already have an excellent electronic distributor that works on exactly the same principle as the HEI. No significant difference... actually the advance curve of the factory distributor is better for your engine than the HEI. And IMO, the factory Duraspark distributor is a significantly better design than the big cap HEI. Just do the TFI/"Team Rush" upgrade and be proud. Get a hot coil or a MSD capacitor discharge module if you want some more spark voltage.

Look here - this is the best "complete" write-up that I know of. http://www.jeepforum.com/forum/f8/i-6-teamrush-upgrade-definitive-669495/[/QUOTE]

Will getting rid of the mcu for the carb not effect the one for the distributor? that is why I am thinking of the gm, but if it does not then I will do the urgrade you posted.

 

No problem. Do the Nutter bypass:



The trigger comes from the distributor via the orange and purple wires (a differential voltage). The black wire is just a ground - makes sure that the ground potential at the distributor is the same as at the ECU (the ignition module).

Before the bypass, the MCU (the ECM under the dash) intercepts the trigger signal and, via the orange wire and ground, either passes it on unchanged or delays it (spark retard). When you do the bypass, you connect the orange and purple wires directly to the module. This is the same way that the Jeeps without the MCU (V8s and earlier 258s) are connected - no electronic spark control. Spark advance then depends on the centrifugal weights in the distributor and the vacuum advance canister on the distributor.

If you are interested, there is a nice article on JeepForum about how to tune the mechanical and vacuum advance on a Motorcraft Duraspark distributor. May be worthwhile after you get the other issues squared away.

If you just add the new cap, wires and rotor, and optionally upgrade the coil, you can even leave the MCU connected. But you definitely would not want to do that if you remove the stepper motor BBD carb.

Clear? hth!

 

Yes, if that is all you have to do I will go that way. Stepper carb is on the way out . Thanks again for the help. I will need more later I am sure. Once I get the carb right on the 7 then it is the steering, after that it is back to the 66, saginaw and tilt+ 2bbl upgrade and others.