4.0 options

[Car RamRod]

I am going to start my 4.0 swap into my 86 manche soon. But first things first, the 4.0 needs a rebuild. I can get a reman longblock from a local machine shop for 1100, with trading in the old one.

 

On the other hand, I know people stroke these engines and do all kinds of stuff, and I wanted to get a good idea of what my options were before I jumped into the project.

 

As for the duty of the engine, it will be daily driven, backed by a 5 speed, and I don't do very much off roading so I don't need a boatload of power. Let me know what you think.

 

Thanks,

Matt

[sinnaevd]

If your DDing it, I wouldn't think about stroking it. If your looking for gas mileage I might consider doing a 4 cyl swap before I would do a 4.0.

 

Your going to run into some 4.0 swapping problems. Toss up a qucik search as it has been covered before, unfortunately I can't find the links at the moment.

 

1100 Isn't a bad price in my opinion for a longblock. But you could also find a whole complete cherokee for that price and steal all the components you need. IF you can find one with decent mileage that may have a poor body that would be my best recommendation.

[Car RamRod]

I should have added that I have a complete 87 that I'll be using to do the conversion. EVERYTHING is gonna get moved over.

 

I picked up the donor for 300 with a rebuilt trans and new clutch in it, but no title. So pretty soon I'll be parting out an 87. ;)

[DirtyComanche]

I am going to start my 4.0 swap into my 86 manche soon. But first things first, the 4.0 needs a rebuild. I can get a reman longblock from a local machine shop for 1100, with trading in the old one.

 

On the other hand, I know people stroke these engines and do all kinds of stuff, and I wanted to get a good idea of what my options were before I jumped into the project.

 

As for the duty of the engine, it will be daily driven, backed by a 5 speed, and I don't do very much off roading so I don't need a boatload of power. Let me know what you think.

 

Thanks,

Matt

 

 

I've spent a lot of time looking into 4.0L performance options. And engine swap options for these vehicles.

 

Rebuilding a 4.0L to stock (or close) specs is probably not an option I'd bother with. I consider the 4.0 to be a decent engine, but it is somewhat lack-luster in the performance area. But, if you're one of those easy-riders who feels that 175HP is enough to keep life interesting, then it would be the cost effective way. Almost! A good boneyard motor would be far cheaper and probably last just as long.

 

Other than you have to swap it into your MJ. Which means the new rad, rad support, tranny, tcase parts, mounts all around, wiring, etc... I'd assume you know at least as much as me about this. So, at that point I think you've got a pretty expensive 4.0L. Not necessarily for the motor itself, but for everything to go with it.

 

Strokers are a good option if your truck is already setup with a 4.0 and you don't mind sourcing parts. At least, the budget ones are a good option. Power output can be upwards of the 250HP range, depending what you do. Excessively expensive engines can produce upwards of 300. For a budget one you have to factor in you'll probably need a 258 crank and rods, plus over-sized pistions, a new cam, bearings, oil pump, piston rings, etc. Plus you'll not want to run a renix head on a stroker, even if you are to run the renix EFI. Again, it starts to get expensive in a hurry unless you have access to a lot of parts. Plus the costs of getting it into your engine bay. Oh, stroker fuel milage typically doesn't suffer over a 4.0, it's not a huge increase in displacement and while cruising you'll burn hardly any more fuel. But if you drive it like you stole it, okay, yeah, fuel will be burned.

 

AMC I6s (actually all inline engines) have mad harmonic problems. They won't survive being revved. Also, the performance cams really like to go flat (non-rollerized engines, yay). And they're heavy clunkers.

 

I'm not really a fan.

 

 

Personally, from what I've seen, there's FAR better candidates for swapping into a MJ/XJ. The platform wasn't designed for a 4.0 in the first place, hence the shoe-horn factory install.

 

 

Oh, wait, didn't realize you had a donor for the swap. That makes everything cheaper when it comes to swapping.

[Car RamRod]

thanks for the input.

 

I'm not really going for a ton of power....my car has me covered there

 

I'm really just looking for something dead reliable that will last, so maybe I should go for the reman 4.0.

 

Matt

[GirsMJ86]

My 91 has a reman Jasper in it. And I could not be happier, they update everything when they do it. Only thing wrong with mine is it sat for too long without being started before I bought it that it now smokes with only 15k miles on it.

 

Alex

[Car RamRod]

well thats kind of a concern.....did you prime the oil pump before startup?

[Eagle]

I'm really just looking for something dead reliable that will last, so maybe I should go for the reman 4.0.

Go for the reman. I really like the concept of the stroker, and I have a friend who has stroked two 4.0Ls (one XJ and one MJ). You can get gobs of power out of them, but you will NOT match the fuel economy possible with a stock Renix-era 4.0L. When my '88 XJ was new, with a 5-speed I routinely got mid-20s highway mileage and on one trip (with a girlfriend and two young children plus paraphernalia for a long weekend aboard) I notched 28 MPG on a 300 mile trip.

 

Plus, there are numerous compromises you have to evaluate in doing a stroker. Unless you NEED the additional power and torque, going stock is probably the wiser choice.

[Car RamRod]

I'm really just looking for something dead reliable that will last, so maybe I should go for the reman 4.0.

Go for the reman. I really like the concept of the stroker, and I have a friend who has stroked two 4.0Ls (one XJ and one MJ). You can get gobs of power out of them, but you will NOT match the fuel economy possible with a stock Renix-era 4.0L. When my '88 XJ was new, with a 5-speed I routinely got mid-20s highway mileage and on one trip (with a girlfriend and two young children plus paraphernalia for a long weekend aboard) I notched 28 MPG on a 300 mile trip.

 

Plus, there are numerous compromises you have to evaluate in doing a stroker. Unless you NEED the additional power and torque, going stock is probably the wiser choice.

 

thats pretty much what I wanted to hear. Being young and dumb it's hard to turn away from more power, but I build engines like that for my cars, and to be honest I just don't want any extra costs or headaches since I really don't need them. I'm hoping I should do well on gas with a healthy 4.0/5speed. The truck has 3.55s in it now, but my tires are taller than stock so I'll see how the engine spins on the highway; I'm gonna look for the 5 speed ratios now and see what I'll be turning on the highway. If it's no good I can swap in the front 3.07s from the donor (I think thats what it has), and I have 3.08s for the 8.8 in the rear.

 

Thanks a lot,

Matt

[Eagle]

I think you're better off with thr 3.55s for fuel mileage, unless you drive insanely fast on the highway. With 3.08s and stock tires. I turn about 1600 RPM at 60 MPH. That's below the engine's torque peak. For optimum economy, you want your cruise RPM to be somewhere near the torque peak.