Eagle

The MJ taillights are unique. From a distance, they look almost identical to Dodge pickups of around the same vintage, and on the NAXJA forum someone once reported "reliably" that the Dodge taillights fit the MJ. They don't. The general style and shape is similar, but the size and proportions are different.

The firewall may or may not need to be modified. Most people who do a 4.0L swap into an 86 or earlier XJ or MJ do have to modify the firewall, some don't. Jeepco is correct about the front end -- the entire radiator and support structure is different for the 4.0L. The easiest 6-cylinder swap is a GM 3.4L from a rear wheel drive Camaro. It's the same block as the 2.8L that Jeep used in 84 thru 86, so all the brackets and "stuff" you'll need are available without custom fabrication.

4.10s won't be enough gear for 33s or 35s with a 5-speed, not even with a 4.0L. My rule of thumb is 3.73 for 30" tires, 4.10 for 31" tires, 4.56 for 33" tires, and 4.88 for anything larger. And it never hurts to go one gear beyond those, but backing off one ratio (taller) is probably a mistake. IMHO, simply forget about running anything larger than 30" tires with the 4-cylinder.

It¿s a GM Delco alternator, but the space in which it fits is tight. It's my understanding (I have not tried to test this) that a higher output alternator has a deeper housing, and it won't fit the space available.

The wiring is NOT the same. Cherokees (except for the 84 thru 86 XJ Wagoneers) have dedicated amber turn signals. The MJs share the same bulbs and filaments for both brake lights, 4-ways, and turn signals. In a Cherokee, you can turn on the 4-ways and the brake lights will work and not lock up the 4-ways. In a Comanche, if you step on the brake while the 4-ways are on ... the brakes lock up the 4-way and they stop flashing. Not to mention that an XJ housing is a completely different size and shape than an MJ housing.

My wife and I just ushered in the new year with a glass of her favorite Chilean wine. Happy New Year to all of you.

And I believe 1990 was the year Chrysler began using the c-clips. Hint -- the designation "Dana 35C" does NOT indicate that the axle is a c-clip axle.

If you do the bolt through the floor, be sure to use an over-sized fender washer under the floor. You don't want the bolt head to pull through the floor in the event of a sudden stop ...

I ran 30s on my XJ with 3.07 gears. It was drivable on the street, but rather "doggy." Not good off-road -- the crawl ratio even in low range was terrible. The 3.73s I put in the MJ were originally bought for use in the XJ with 30" tires, and I still think 3.73 is the optimum all-around ratio for 30" tires. But that wasn't a factory ratio. If you're shopping for complete axles in a junkyard, I would favor 3.55 if it's a daily driver, and 4.10s if you do much off-roading.

Unless he got a kit with a drop track bar bracket and pitman arm. But unless your kit is a 6"+ lift there is no need to mess with the pitman arm. BTW... What lift are you installing? Doesn't matter what lift he's getting, the pitman arm is indexed and he can't "straighten" the steering by trying to "clock" the pitman arm on the steering box output shaft. If he did manage to do that, all it would do is put the pitman out of alignment with the steering box, which will cause further problems in the future. Just use a pickle fork to bust the drag link loose from the pitman arm.

I think a recent post suggested that Rusty's is now offering a WJ style LCA for the XJ/MJ/ZJ. Dunno that I have much faith in anything from Rusty's, but check his web site and see if he lists it.

The '84 through '86 tachometers did not have the adjustable potentiometer. The '88 through ?? did. I am not sure if '87 went with the old style or new style, or if they may have used some of each in the '87 model year.

That's the one!

You have a 4-cylinder, right? Did the tach come from a vehicle with a 4-cylinder? If not, that's the problem. Aftermarket tachs have a switch to set them for 4, 6 or 8 cylinders. A tachometer just counts ignition pulses, and spins a needle on a dial that's calibrated in RPMs. Our engines are 4-cycle, so each revolution only fire half the cylinders. If the tach is calibrated for a 6-cylinder, 3 pulses indicate one revolution. But a 4-cylinder engine only produces 2 pulses per revolution, so it has to spin 1-1/2 times to have the tach show 1 revolution. If you have a 6-cylinder tach in a 4-cylinder vehicle, when the tach reads 3000 RPM the engine is actually turning at 4500 RPM.

If your route takes you near the junction of I-80 and I-81, be sure to check out Harry's u-pull junkyard. It may be the biggest u-pull in the known galaxy, and usually has a bunch of XJs and MJs. It's in Hazleton, right off the highway a couple of exits south on I-81 from the I-80 interchange.

There are actually two routes to go with the metal replacement. I used a Moroso racing surge tank. It's a universal part made for racing applications, and it's available (for less money than I paid at my "friendly" local speed shop) from Summit Racing. To use the Moroso, you have to buy a few standard copper pipe fittings at a plumbing supply house and know how to sweat copper pipe joints. More recently, some enterprising company has come up with an all-metal replacement for the XJ/MJ tank that is flat, fits in the OEM location, and has all the fittings built in. The initial cost of this one is higher than for the Moroso, but by the time you factor in the extra parts needed for the Moroso and the extra labor to sweat the fittings and make a mount -- the newer one is probably the preferable option. There were photos of it on here awhile back. I don't have a link to them but you should be able to find them.

No. Not true. Not until it gets so low the pump can't pick up oil. At that point you don't have low oil pressure, you have no oil pressure. Those numbers do not indicate "good." The factory spec is 13 psi minimum at 650 RPM idle, and 37 to 75 psi above 1600 RPM. As BLHTAZ noted, that's at normal operating temperature. Most 4.0L XJs and MJs run between 50 and 55 psi on the highway at the speed limit, which is around 2000 RPM (or lower if you have a 5-speed). Your pressures are marginal, at best. What weight oil are you running?

Looks good to me just the way it sits. Nice MJs are too rare to be chopped up and modified, IMHO. That's what junkers are for.

+1 to the above. Check with a mechanical gauge, and be sure NEVER to use a FRam filter. But ... you don't seem to understand what the oil light does. It's not a warning on low oil level, it's a warning of low oil pressure. The dipstick tells you the level, not the light.

You probably need to clean and lubricate the ratchet on the foot pedal.

For starters, if it's a 1990 you don't have a carb.

If it's an '87 it isn't a V6, and if it's a V6 it isn't an '87. If it IS a V6 and it has 289,000+ miles on it ... run away as fast as your legs can carry you. That engine isn't even heavy enough to be a decent boat anchor. The 4.0L I-6 will live to that kind of mileage -- my '88 is around 282,000 right now -- but it's pushing things. I bought mine new and I know the oil has been changed religiously. The AMC I-6 is an incredibly durable engine, but everything has limits. If it is a 4.0L and it feels gutless ... there may be problems. Keep in mind the early 4.0L engines were drag race engines -- they make low-end torque rather than high-end horsepower, so the 2000 feels a lot "gutsier," but it's largely because it runs freer at higher RPM. They both get about the same gas mileage (low 20s), so my old one isn't quite finished yet.

Try Husky Spring. Home page www.huskyspring.com or http://www.huskyspring.com/main.taf?cat=132

It all depends on what radio package was ordered. My '88 Chief has them. My '87 Pioneer does not.

Adding a second MJ main leaf should give you between 1" and 1-1/2" of lift, and should not detract noticeably from the ride. If the main leaf doesn't provide enough lift, splice in the second leaves from the donor packs as well. Cut the tips off so the ends fall between the number 2 and number three of the original leaf pack.