Eagle

Ya know ... Just thinkin' out loud here. I have NOT done this, but with 287,000 miles on the '88 XJ I'm ... exploring options. Jeep sells (or used to sell) an MPFI conversion kit for the old, carbureted 4.2L engine in the early YJ Wranglers. Essentially, the conversion was the intake manifold, throttle body, injection, and engine room wiring harness from a 1994 Wrangler 4.0L with the HO MPFI system. It was NOT necessary to rewire the entire vehicle to install this kit. If you can convert a carbureted Wrangler to the HO MPFI without rewiring the entire vehicle, I have trouble understanding why there is any need to rewire the entire chassis when the engine harness appears to be functional as a stand-alone conversion.

There were two types of speedo cable. The first style, used from 84 (for the XJ) and 86 (for the MJ) either only through 1986 or possibly part way through 187 used a metal retaining clip and a screw to attach the cable to the speedo head. From 1988 (or mid-1987) through 1990, the retainer was a white nylon clip. To remove that, squeeze the outer retainer ring and it should come right off. It takes a bit of experimenting to figure out which orientation to squeeze. When you get it, it's easy. Don't force it.

umm...no I don't have an open system (as far as I know)... I still have the overflow tank, I don't have a rad cap, etc... I can't say that my rad wasn't replaced by the previous owner at some point...above the lower rad hose (on the driver side), there isn't any other port or anything Wade, if you do NOT have an open system, then you do NOT have an "overflow" tank. If you are referring to the plastic bottle on the passenger side of the firewall, that's not an overflow tank, it's a surge tank and it is under full system pressure. The cap to that tank is your "radiator" cap. The temperature switch that controls the aux fan should be in the driver's side radiator tank, just above the lower radiator hose. The sender has a pigtail that would plug into that connector in your photo. There should also be a standard relay on the driver's side inner fender that's part of the system. Since your radiator doesn't appear to have the sender, the simple solution for you would be to just find a matching connector and wire it to a toggle switch on your dashboard. You don't need to tap power, that's already there. Just run both wires to the switch to open or close the circuit.

"Boxes"? WHAT boxes? If you mean the taillights, no they aen't anywhere near the same size or shape. I think a REALLY good body man could make '97 XJ taillights fit in an MJ box, but it would be work.

I'd say you are leaping unerringly to a couple of illogical conclusions. As CWLONGSHOT noted, 20 psi at idle is withing spec. However, the pressure should be around 40 or better (warm) at 2000 RPM. The factory spec is 13 psi (minimum) at idle, and 37-to 75 psi above 1600 RPM. So your pump is producing pressure, as evidenced by the idle pressure, but it can't boost the pressure above 20 psi. That doesn't sound like a clogged screen to me. Even if it did -- you could just drop the pan and clean the screen, it doesn't mean you need a new pump, and it CERTAINLY doesn't mean you need a new high volume pump. Your problem is pressure, not volume. Then you ask about the rear main seal. The RMS has nothing to do with oil pressure. It just prevents the oil from leaking out of the engine. By all means, if you have the oil pan off that's the time to replace the RMS. But that's not going to cure your oil pressure problem. IMHO, you need to replace the bearings, not the oil pump. It can be done with the engine in the truck.

That's insane. I knew tornadoes were powerful, but I had no idea a twister could pick up a freakin' TRAIN.

Ditto.

A SHORT AAL does make the ride stiff. That's one of the reasons to go with a long AAL. The XJ that I did using cut-off XJ main leaves rode VERY nicely after the "lift" (if you call 3/4" net increase a "lift"). I'm in Connecticut and the ex-GF I built it for is in Montana, so I drove it 2400 miles (or so) to deliver it. I think I was on the road three days, and there was definitely no harshness to the ride. By contrast, the short AAL that was under my '88 MJ when I bought it was pure torture. Much of the key is keeping the arch basically the same. When you stuff in a short leaf and use that to generate 3" or 4" of lift, that one leaf has to do a LOT of work, so it has to be thick, heavy, and stiff.

Spin the ring gear. The tooth count is stamped into the edge. It won't be a ratio, it will be two numbers -- the number of teeth on the ring gear, and the number of teeth on the pinion. Divide the big number by the small number and there's your ratio.

Nope. YJs had high pinion D30s ... but they are set up for leaf springs, so they aren't exactly bolt-ins. TJs and ZJs are all low pinion.

I dunno what's "best." I know using the stock plates and flipping them side-for-side will preserve the original shock geometry and allow you to run factory-length shocks. That would be my choice, but I'm not a hard-core wheeler.

That's not comparing apples to apples. The 4.2L never had multi-port injection, and it used an older ignition system with a rather lousy carburetor. Aside from that, the raw numbers are deceptive. It's a function of what you're looking for. The 258 didn't wind up real quick, like a short-stroke V8 engine does, but it had gobs of torque off the line and it just kept pulling all the way through the RPM range. Yes, we had a few. My brother raced a 258 Gremlin, and we had a Hornet AMX in the family for a number of years.

Hunting arrow Get your mind out of the gutter ...

I would. Otherwise there are too many variables, and trying to do it on your own could EASILY run upwards of $2,500 by the time you get done. $2,750 isn't that far off the price of a Jasper rebuild, for heaven's sake.

You sure you didn't have them look up Comanche? 1992 was the last year the Comanche was produced, but the Cherokee continued through 2001. Obviously, NAPA is incorrect. The hubs AND the rotors changed between 1989 and 1990. And since the steering knuckle and calipers also changed at that point, and the caliper mounts to the knuckle, it is critical to keep ALL the parts within the same "generation." You cannot mix and match, or you get an interference fit (like you did), or no brakes.

Even an AAL that has the same arch as the other leaves gives some lift. For example, a popular home-brewed AAL for the XJ is to cut the eyes off a second pair of XJ main leaves and use them as AALs. In a newer vehicle with newer "donor" main leaves, this generally results in about 1-1/2" of lift ... 1-1/4" plus a quarter for the thickness of the extra leaf. And the new leaf has the exact same arch as the original main leaf. I did the same thing on an older XJ (an '88), using main leaves out of a wrecked 89 or 90. The rear had sagged about half an inch below the accepted norm of 17" from axle centerline to bottom of flare. After the AAL, it sat at 17-3/4", so the AAL grossed 1-1/4" of lift and after correcting the sag left me with a net lift of 3/4". This XJ was for an ex-GF to use as a daily driver in Montana so that was all that was needed. I just wanted to get it back up where it should be, and reinforce the tired springs a bit.

Probably. Ask Bob Salemi, the guy who owns that record-setting MJ drag truck. He has a stroker in his daily driver MJ. I think he had it dynoed to get the correct injector size. His is an 89 IIRC. I'm pretty certain it's a Renix.

Lift increases toe-in. Ideally, it should be approximately 1/16" with standard size tires. (The older FSMs listed it in inches, the newer ones give degrees, which is more accurate and isn't affected by larger tires.)

Please write in English on the forum, don't use TXT MSG shorthand. Us olde phartes can't read that junk. There is no practical limit on post size and you don't get charged by the character here, so there is no reason not to use the common language - English.

One word: WOW! I wonder how much a crate 4.7L costs? I know what I'd like to drop into the '88 MJ 4-banger sitting out front ...

I have posted this before, but I guess it's time to repeat. As before, this is taken from a book I am writing and it IS copyrighted. In posting it here, I am NOT granting permission to reproduce it anywhere besides here. Please respect my copyright:

:agree: The 4.3 is, as noted, just a shortened small-block V8. It's a 90-degree engine that's really too wide to fit easily into an XJ or MJ engine compartment. You will need all the adapters and such you would need to do a V8 conversion, but you lose two cylinders. A MUCH better swap is the 3.4L V8 from rear wheel drive GM cars like the Camaro and Firebird. It's a 60-degree engine, so it's a lot narrower. Also, it happens to be physically the same block as the 2.8L that was used in the early XJs and MJs, so mounts, manifolds and brackets don't have to be custom fabricated.

This is (I think) the first time you have actually mentioned that. I have been continually baffled by all the references to fabbing when you should already have everything you need. Now I understand. (Gotta love previous owners -- NOT.) I don't think that aftermarket thing is actually what you need. The caption refers to it as a "slider insert" for the spring plate. Also, the way they did that is @$$-backward. The spring plate should go on TOP of the spring when doing a SOA conversion, and the U-bolts are all you'd see under the axle. What they did was leave the original perches under the axle, use flat plates on top of the springs, and keep the original spring plates under the axle, on the original perches. It would have been MUCH easier to just swap the stock plates side-for-side, mount them on top of the axle (where they belong) with standard U-bolts, and then the shock length wouldn't have to be changed. Plus, of course, you wouldn't NEED "slider inserts" for the spring plates under the axle.

.060 over only brings you to 4.6 or 4.7 liters with a stock 258 crank, so to get from there to 5.0 liters is one helluva offset.

This is for a Renix-era vehicle, so the newest engine that could be a direct replacement would be out of a 1990 XJ or MJ. There was no ZJ back then, and the Wranglers thru 1990 didn't get the 4.0L engine. Chances of finding a low mileage engine in a 1990 or older vehicle are rather remote. I think it makes much more sense to do a preemptive strike on the engine that's in the truck. The pan has to come off to do the rear main seal, and getting the pan off is a PITA. So it only makes sense to throw bearings in while it's open.