3.4l vs 4.3l

Hi,

I've searched the site, and see putting a 3.4l or a 4.3 l into a Cherokee is doable.

I have a 1987 Cherokee 2.5l, 5-spd manual. The 2.5l went tits up. So now I have to decide which engine to replace it with. I'm leaning towards the 3.4 because the existing tranny should bolt onto it. My buddies want me to go with the 4.3, saying it's a more reliable engine and it would be fun to have that much more performance.

Is this just a personal preference question? Or are there compelling reasons to go with one over the other?

This vehicle will be my "take the kids camping" and winter vehicle, I don't plan to do any off roading, not that I did much before.

TIA,

Mark

You can give your Jeep bigger tits in the form of a Jeep 4.0 I6 engine with AX15 5-speed tranny. It'll be a lot easier to do this conversion than a Chevy and the Jeep combo is also virtually bombproof.
Make sure you also get the engine computer, wiring harness, sensors, EFI system, fuel lines, fuel pump, intake/exhaust manifolds, distributor, coil, ignition module, gauge pod etc from a 4.0 XJ to make it all work.

For ease of installation, the 3.4 certainly would be your best bet. About the only consideration after that would be to determine if you want to run the fuel injection system or swap it to a carb. Since it sounds like you will be using it on the roads for transportation as well as your camping vehicle, I'd make sure you're up on the current emissions and vehicle modification laws in your area. It would really suck to do a big swap like that and discover it's not legal. Also, if you look for a donor car for the 3.4, look at the '93 to '96 Camaro/Firebird's that already have the manual tranny so that you can get the correct flywheel. If I recall correctly, you don't want to use the flywheel from your Cherokee as there's a difference in how they were balanced. I believe the 3.4 has a flywheel that is balanced and indexed specific to that crank. Additionally, I'm not sure about which pressure plate/clutch disc you'll want to use. There's a possibility you might have to use a Camaro/Firebird pressure plate to mount up to the flywheel, and an XJ clutch disc so that the input shaft splines are correct.

If you tow or plan to tow any trailers with your vehicle, then I highly recommend you swap in the 4.3 and use the factory fuel injection from the donor vehicle. I had the 4.3 5 sp from a '92 S-10 truck in my first XJ and I still miss it over the 4.0 HO in my current '93 XJ. The 4.3 swap isn't super difficult, but you'll want to take the entire drivetrain from the donor vehicle (engine, trans and t-case) so that the computer system will work with less hassles. And you're correct, your current trans won't bolt up to the 4.3 - nor would you want to use it since it wasn't made to handle the increased power. With this swap, you'll have to buy custom motor mounts from Advance Adapters and move your tranny crossmember back a few inches to accept the different tranny. Some people have used the factory wiring harnesses, but Painless Wiring makes a neat harness fairly reasonably priced - that's what I used. You'll also want to get a newer gas tank from a mid 90's Cherokee with the internal pump, it puts out the correct fuel pressure and volume that the 4.3 fuel injection needs.

Remember that since you've got the 4 cyl now, you're gonna need to replace the majority of your exhaust system with either of these swaps- particularly the catalytic converter since it won't be designed for the increased flow and heat. Same thing with the radiator. My 4.3 didn't like the original 2.8 radiator and I had a bigger one made.

I have a fairly detailed write-up about installing the 4.3 if you're interested, just send me your e-mail addy using the Private Message feature here and I'll send it to ya.

Good Luck!

The Cliff's Notes version is that the 3.4L is a small, 60-degree V-6 that is externally identical to the 2.8L V-6 that Jeep used in the Cherokee from 1984 thru 1986. The bellhousing pattern is the same as the Jeep 2.5L 4-cyl, so your existing tranny will bolt up to it.

The 4.3L is a 90-degree V-6, essentially a small-block V-8 with two cylinders lopped off. It fits in the XJ engine compartment, but it is tight, and to make it work you go through as much adaptation as you would to stuff in a V-8.

Given the use you have outlined, the 3.4L would be a far more economical swap for you.

Or you could do what Ghost did, and plug in a 91 or newer 2.5L with multi-port injection.

makmadison said:

My buddies want me to go with the 4.3, saying it's a more reliable engine and it would be fun to have that much more performance.

Click to expand...

I dought that a 4.3 V6 (although still great engine) would give you much more power over the 4.0 jeep I6 unless you go vortec. I have raced two pre-vortec 4.3L chevys (1 older s-10 pickup and 1 s-10 blazer) beat them both. Both were autos though. And I don't think reliablitly is bad for either. Just my couple cents. Good luck with whatever you do.

Thanks for the replies.

I'm going to keep looking for a 3.4l. I'm in Madison, WI. I found a couple down in Rockford, but none came from a Camaro/Firebird.

Mark

Find a 87-90 xj with the 4.0 that is wrecked that the owner will sell whole! then swap the 4.0 into the 87. It would be soooo much easeyer and cheaper if you try to retain the FI on the 3.4..... Look for Crimsonride? He is doing this swap and keeping the FI, the only way IMHO to do this swap.

makmadison said:

Thanks for the replies.

I'm going to keep looking for a 3.4l. I'm in Madison, WI. I found a couple down in Rockford, but none came from a Camaro/Firebird.

Mark

Click to expand...

as long as they don't come from a front wheel drive vehicle, then your golden.

something is different between the FWD and RWD engines, I think the starter switches posistions.

also you will need a external fuel pump, because the 3.4 doesn't have a mechanical pump

and one more thing, you will need to use the flexplate(flywheel) from your 2.8L, but you MUST have the fly wheel machined to zero balance,(grind off the wieghts on the 2.8L flexplate )

there are tons of write ups on how to do it. this is the best source I have found. http://www.lunghd.com/Tech_Articles/Project_XJ/Project_XJ.htm

don't do the 4.0 swap, I thought about doing it to my 84 from my wrecked 87... jebus, you need to change alot of things and I felt it wasn't worth it.. of course I am lazy..

Oh wait, I just noticed you have an 87..

then by all means do the 4.0 swap. it will be even easier than the 3.4 swap..

for some reason I thought you had a 84-86 cherokee. your jeep is begging you for the 4.0.. heed its call.. you can buy my wrecked 87

RINGKONG said:

Oh wait, I just noticed you have an 87..

then by all means do the 4.0 swap. it will be even easier than the 3.4 swap..

Click to expand...

Except that the 4-cyl transmission won't bolt up to the 4.0L block.

Eagle said:

Except that the 4-cyl transmission won't bolt up to the 4.0L block.

Click to expand...

thats why he needs to buy my 87 or find a donor close to home.

in omaha, 4.0 cherokees with the aw4 are a dime a dozen at the local upullit... but its tuff to find my 84-86's.. go figure...