2.8l

i am looking at buying an 84 model with a 2.8l v6.

this will be the daily driver ( although i ride a motorcycle everyday....this is the first "car" ive had in 2 years ) and the weekend toy.....

what is the biggest tires i can reasonably put on and keep the xj useable for things like pulling the boat and the motorcycle trailer ( sometimes a loooong way )?

i know ill have to put in gears but each motor has its power limits....you just cant turn 44s with a 4-banger........:banghead:

Try and find a 87 or later xj witha 4.0 liter.

dude its an 84 4x4 in excellent shape for 750.00

i wouldnt even buy a "car" if it wasnt such a good deal........

but since i looked at it and started lurking around this place ive become very interested in the xj.

i had an 85 bronco II for a while and loved it........the only thing holding it back was the lack of lift ( it would high center easily ) and my lack of income to fix that problem!

but now i have a lil more money to play with so......time for a new toy!

x2, you won't be pleased with a 2.8.... They're notorious for only lasting about 90k between rebuilds.

robertmayton said:

i am looking at buying an 84 model with a 2.8l v6.

this will be the daily driver ( although i ride a motorcycle everyday....this is the first "car" ive had in 2 years ) and the weekend toy.....

what is the biggest tires i can reasonably put on and keep the xj useable for things like pulling the boat and the motorcycle trailer ( sometimes a loooong way )?

i know ill have to put in gears but each motor has its power limits....you just cant turn 44s with a 4-banger........:banghead:

Click to expand...

Before you think about tyres, that engine will need some help. OK - a lot of help.

The 2.8L V6 is best used as an anchor for your boat. Period.

You can look for a 3.1 or a 3.4 donor in either S10/S15 series trucks, a GM F-body (Camaro/Firebird,) or you can crawl under FWD vehicles and look for a start motor mounting pad on the REAR of the engine, as mounted (some FWD vehicles will have Goodwrench Service Replacement engine blocks, which have starter motor mounting pads on BOTH sides of the engine. The FWD has the starter on the wrong side for RWD/AWD/4WD applications.)

You can either swap the intake to the 3.1/3.4 and upgrade the carburettor, or just get all the electronics from the donor vehicle and swap in PFI. The 3.1 and 3.4 should bolt right in - you can grab the 700R4 and transfer case behind it if you're so inclined, but I don't recall what transmission (offhand) was behind the GM V6 in the XJ and MJ, and that may be a step backwards (The 700R4 makes a good anchor as well.)

For more information on swaps, I refer to you www.gm60degreev6.com (.org? I don't recall offhand.)

However, if you plan on towing, I'd second the idea of getting an 87-up with the 4.0L. You get a lot more torque - and a lot more usable torque. Plus, it's just a better engine to begin with.

That is not a good deal. I have seen 2.5L xj's that run for $500 and less.

I bought my 87 4.0 for 800 and you can newer better ones for around that price.

ok nevermind ill just figure out myself....

i didnt ask if it was a good motor i asked what size tires it would turn.....

this is not a big deal...not a MAIN mode of transportation......just a toy and a wet weather ride....this jeep is rock solid and dependable......even has a/c ( in houston thats a big thing)

the roughest terrain its likely to see is some mud and maybe a few trails....

in all honesty i am thinking of a full drivetrain swap in 2 years when it doesnt have to pass emmissions testing .....

what ever ill just put the 5.5 inch and 33s and be happy!

The biggest stock tires are 30x9.5

ok thanks nevermind

ill find a new life and a new forum

Dude!!! Those were all honest answers....and good advice...but as for tires...go as wide as you like...but tall will kill what little power the thing has unless you regear it big time.

ok thanks for the response muddawg ....

let me re - word IF you had a 2.8l what is the largest tire you would run until you could do a engine swap

First of all dude - calm down. Every one on this forum wants to help but you have to be willing to listen.
Second - they are right. The 2.8l was a deaththrow for AMC back when they owned Jeep. They only made the Cherokee for 2 years b4 AMC went bankrupt and sold Jeep to chrysler and dropping that car engine into a 4x4 was one of the dumbest things they did. Also the that year uses a GKN driveshaft that differs greatly from the Dana unit Chrysler used. Ive seen those Gkn units shatter with 30in tires on the street under mild torque. The peugot transmission also lacks strength eapecially when stacked up against Aisin-warner units of later models. Plus, cherokees made from 84 -87 use an inferior cooling system that leads to overheating even in that little 2.8l.
Third- I hope that stops you from buying that jeep
Fourth- If you really want to buy it dont put anything on it bigger than 30 inch tires and take it easy on the skinny pedal with that.

IMPORTANT QUESTION: Is it manual or auto trans???? The auto trans will be more forgiving with bigger tires, but without regearing....no more than 30's...or it won't pull a greasy string outta a cats butt...and forget a lift kit without changing the front shaft out for a double cardin....the GNK will not handle the angle....been there, have the t-shirt.

My trail rig is a 85 model with a 2.5 4 banger....it does real well with 4.88 gears and 33's....but not as good as a 4.0 for sure. Why build a rig with a 2.5??? because everybody said they suck....seemed like a real challenge....and i wanted a motor that i could flail mercilessly...it fits the bill for that...300ft runs in the pit at 7,500 rpm.

AUTO

and i planned on re-gearing to match the tires

the truck drives fine with plenty of power ( about the same as a 2.9l ford )

30x9.50s right now, no problems

robertmayton said:

the truck drives fine with plenty of power ( about the same as a 2.9l ford )

30x9.50s right now, no problems

Click to expand...

If you've got "plenty of power" out of the 2.8, consider yourself fortunate.

I'd probably not go much larger than 30's or 31's with that engine, even with re-gearing and a budget boost. The engine really is going to be your limiting factor there...

The 2.8L was used in 1984-85XJ and 86 XJ and MJ because the 4.0 was still in development, and AMC wanted to offer a six-cylinder option rather more quickly than that. Why they didn't use the 258 as an option, I don't know - it would have saved the redesign of the front clip for 1987XJ/MJ, and they could have saved a bundle (both in engineering and in purchasing engines.)

Before you re-gear, you should really find a new engine. I've owned vehicles (not Jeeps) with both the 2.8L V6 and the 3.1L V6, and the difference was night and bloody day! Both were PFI, and they were only a couple of years apart. The Corsica (with the 3.1) was actually about 300-400# heavier than the Cavalier (with the 2.8) and I drove more people around in the Corsica - and the Corsica had more balls than the Cavalier could ever hope to have. That, and I was getting tired of doing valve cover gaskets every 3-4 months (they always ended up leaking at the three-way junction of cylinder head, intake manifold, and valve cover - no matter what I tried to stop it. I should have called that car the Exxon Valdez...)

If you want to go much larger than 31's, an engine swap is in order. If you want to tow with it on a consistent basis - still an engine swap is your best bet.

I really am trying to offer helpful suggestions - but larger tyres and a re-gear don't fix a shonky engine, and those 2.8L engines just don't last to begin with...

i have an 84 2.8, with 31 inch tires and 4.10 gears, it pulls fine, i put an exhaust on it and rebuilt the carb. It runs perfect and I can take 4 banger xjs all day long.

You really need to find out what gears are in the axles too. And check for the CV booted shafts. They suck. Some of the 84's had 3.73 and others had 3.55. It may have 3.55's if so you could get away with 31's and 4.10's. I ran 33's with 4.10's and it did ok. It could nto get out of its own way but it pulled decent on the trail.

We sure an opinionated bunch are we not?

I have no experience with the 2.8, but everyone says it sucks. On the other hand, I know a guy who tells everyone to trash the 4.0 and put an LS-1 in there.

Here's my advice. Test drive the jeep. If you like it, and are satisfied with the power it has, have a good mechanic go over the engine. Don't skip this step.

Assuming the suspension hasn't saged too much with age, a Cherokee will run 31" tires with no lift ON THE STREET ONLY.(everyone can start flaming me now,..) Much trailer tongue weight or just about any flex, and the tires hit wells, flares, seams, liners, and anything else they can grab.

For towing, 30" tires are probably your limit, and you're going to want to regear. Here's some simple math:

New tire height / by old tire height. This will give you a number like 1.08. remember it, then find the gear ratio installed on the truck now. To do this, look for a metal tag held on by the 2 bolts on the front axle cover. There will be a lot of numbers on the tag. look for a set seperated from the others that read: 3.55, 3.73, 4.10, something like that This is the gear ratio.

Take the tire size ratio you figured earlier( the 1.08 or whatever ) and multiply by the gear ratio. This is the gear ratio you will have to install to get the power levels back up around what you have currently. If you want to tow, go one step lower to pick up a little more omph without affecting drivability.

Heres what it looks like

Current tire: 225 75 - 15
Tire you want: 30 9.50 - 15
You have 3.55 gears.
The 225 is about 28" tall, so

30 * 28 = 1.0714

3.55 * 1.0714 = 3.80
Closest ratios are going to be 3.73s or 3.91s, for towing you consider 4.10, realizing you mileage will suffer a little but the engine/trans will last longer. It gets harder to play the number game as you go lower, there's a big step to 4.56 as the next commonly available size gears.

If you buy the jeep and decide on a swap, here's a guy who did one and the writeup:
http://www.lunghd.com/Tech_Articles/Project_XJ/Project_XJ.htm
Lot of good info here.

Remember to figure not only the cost of the jeep, but also the tires your adding,(300-500) bu the cost of the gear swap(figure about 450-600 in PARTS if you can do the work yourself) when you do the math on buying the baby. IF you want the tires soon, the gear have to go in right after(or before) if you want to tow.
A little humor now: about 2 years ago I felt lazy and called Jeep about rebuilding my rear axle(just a new bearing kit, keep my gears) parts and install from mother Mopar: just over a grand.
I'm not lazy any more, and Mopar sure is a mother.