The CJ Needs A New Engine...But Which One?

[WINDSHEAR II]

Hey guys,
I have a late model '86 with factory Dana axles front and rear (30 and 44). The truck has the stock Dana 300 linked to a T-5 tranny. Apparently I was once insane, because I loaned the Jeep to a family member who managed to kill it in less than 4 months. The engine is gone.
Now I must decide between two "practical" choices:
1) A 1994 4.0 litre engine needing a wiring harness, but complete.
2) A GM 4.3 litre crate engine using salvage yard electrics.

NO 4-wheeling for this one (have another stock running CJ7 ), and I have no hangups about it no longer being "stock". This vehicle will be used on-road mostly, but will be required to TOW a 23' sport boat on occasions. Brakes will be upgraded, tranny too. 31" BFG mudders with a gear ratio change. All of that is planned out, but I need to hear from guys who have done the engine change!
Thanks in advance...where should I be headed?

 

[Saddle Tramp]

Just drop a rebuilt AMC 258 i6 / 4.2l back in and call it a day. Cheapest, easiest way to get back on the road, and as always, keep your Jeep, Jeep. There aren’t many nice CJs left in the world; it is a crime to castrate another one in the name of GM. If you must go for the 4.0.

 

[WINDSHEAR II]

Just drop a rebuilt AMC 258 i6 / 4.2l back in and call it a day. Cheapest, easiest way to get back on the road, and as always, keep your Jeep, Jeep. There aren’t many nice CJs left in the world; it is a crime to castrate another one in the name of GM. If you must go for the 4.0.

Thanks bud, your input is appreciated! In the post I neglected to say that having EFI is a must for the new engine. I'll admit that I am leaning toward the 4.0l since it would be the least trouble to install. An NV3550 will replace the T-5 , meaning only one adapter is needed to mate the new tranny to the Dana 300 TC. I'll probably go that route and plan on using the Jeep engine, unless someone here REALLY makes a case for going GM!
That means ~$1750 for a Hesco harness kit !

Stephen

 

[cj rob]

I have a 82 CJ7 and I do agree that keeping jeeps, well jeeps is good and all. But technology has come a long way. I have the 2002 vortec 5.3 in mine and has all the power I need. Great for towing and excellent in the deep stuff. I have been buried more than once and it will just not quit. I love it. Decent fuel economy, figure around 20 hwy or so. The vortec and LS series engines have a huge following and even bigger after market and they are very plentiful in salvage yards.

 

[raser13]

An NV3550 will replace the T-5 , meaning only one adapter is needed to mate the new tranny to the Dana 300 TC.

Hey man, if your ditching the T-5 my brothers been looking for one. Pm me what you would want for it and I'll let him know. Plus it'll give you a little more cash towards your engine swap.

 

[Neuner]

I'd lean towards the 4.0 especially since that is the route I chose. Love it.

Not sure about pulling a 23-footer with 2.73 gears though. Guess it would depend on the gross weight and other factors?

 

[Saddle Tramp]

I have a 82 CJ7 and I do agree that keeping jeeps, well jeeps is good and all. But technology has come a long way. I have the 2002 vortec 5.3 in mine and has all the power I need. Great for towing and excellent in the deep stuff. I have been buried more than once and it will just not quit. I love it. Decent fuel economy, figure around 20 hwy or so. The vortec and LS series engines have a huge following and even bigger after market and they are very plentiful in salvage yards.

CJ Rob- Sure technology has come a long way and I doubt anyone here would argue BUT one does not buy a CJs to embrace “New Technologies” but rather to embrace the lack of technology. However I understand the want of fuel injection too and can embrace transplanting a 4.0 into a CJ as it is an OEM Jeep item. In my mind that’s still keeping your Jeep, Jeep where other than the odd fire Buick, a GM motor has no place between the rails of a CJ. Remember, Jeep owned the tooling for that V6 at one time.

 

[WINDSHEAR II]

I'd lean towards the 4.0 especially since that is the route I chose. Love it.

Not sure about pulling a 23-footer with 2.73 gears though. Guess it would depend on the gross weight and other factors?

Neuner, yeah I've decided to go with the 4.0l and keep things relatively simple. I also need to update my profile, since I purchased a CA CJ7 almost 2 years ago! It's a daily driver to work and back during the week. Rust-free and original, even has the factory emissions in place!
The project CJ will be built for the highway, using standard stuff (4.0l, NV3550, 3.73's with a Tru-Trac, 31" BFG Mud-Terrains). It already has a Dana 44 rear axle, so I'm set there. Gonna go hard at the braking system though, and get the Vanco Hydro-Boost system and accessories. Along the way, I'll swap this, replace that, tweek those until I have it about ready. I want a really nice set of Recaro or Corbeau seats when I have the funds to just burn!!

Stephen

 

[Neuner]

Sounds good. Keep us updated on this thread or another as you go along.

and....unlike Pete....post some pics!

 

[Jimbos76cj]

I see you settled on the 4.0. I would consider a 4.8 chevy LS motor. Big issue with using the 4.0 motor is lack of diagnostics and tuneability. any one that can reprogram a 5.3 or 6.0 can reprogram a 4.8. It will make almost double the horse power then the 4.0 will.

 

[Neuner]

Big issue with using the 4.0 motor is lack of diagnostics...

What do you mean? My 4.0 is OBDII, same as the 4.8.

 

[Jimbos76cj]

Most people swap the OBDI system in. I've read it takes a lot less wiring then the obdII. You can diagnose most carbed motors with very basic tools where you need a reader for the FI motor. The chevy Ls motors are a pretty easy wiring to make a 4 wire system, it's obdII and their computers are easily programmed.

 

[Neuner]

Most people swap the OBDI system in. I've read it takes a lot less wiring then the obdII.

Someone out there started this rumor and I'd like to know who because they are incorrect. The only additional wiring the OBDII has over OBDI is one extra O2 Sensor downstream for the non-California systems. That's it and it's not needed for the engine's performance, only to check if the Cat is working.

 

[Jimbos76cj]

Every thread I read says OBDI system. I dont think it has to do with the sensors as much as the computer having a harder time adjusting to mods. Now I think about it Ive been hitting the net hard for both 4.0 swap and Stroker motors so maybe Im getting the info mixed. Do you have any info on the OBDII swap you can share? Ive already got a OBDII intake and injection parts I just need the wiring and comp.

 

[Neuner]

Do you have any info on the OBDII swap you can share? Ive already got a OBDII intake and injection parts I just need the wiring and comp.

What would you need? I have the FSM manual for the make and year of my 4.0 but unfortunately it varies enough that you'd have to get the correct one for your engine. I'm in no way an expert, and don't claim to know much but picked up some snippets of info as I tried to figure mine out. I had debated about keeping my AMC 258 i6 / 4.2l to later help with a stroker but the wife greatly deterred this path and encouraged its sale.

I went through and studied the wiring heavily for several months before performing the swap to verify what sensors and wiring I needed and since I didn't have the PDC harness. The wiring concept isn't much different between OBDI and II. OBDII is a more standardized communication protocol. There are 5 different versions and I believe Chrysler's use CAN-BUS but some of the earlier models or variants may use SAE J1850 VPW? The ones that seem to be against II is because it doesn't have a straight forward check engine light they can put on the dash or clearing the codes of the missing sensors can be difficult for some state inspections. Our state isn't strict and I use a bluetooth device to read the status of the PCM while I'm driving which is what I've seen most others do.

It depends on the PCM and if it is flashable/programmable is what makes the difference. Most Chryslers/(GMs?) are not from what I gather.

I got the PCM through the salvage yard market, Car-Part.com--Used Auto Parts Market, for $35 off of a manual '98 XJ. It's a PCM because it also controls the Transmission and not a ECM which only controls the engine. You can buy aftermarket ECM's which are fully programmable and what I've seen most of the strokers use.

I bought my engine with the Engine harness. I later found a PDC with the second PDC harness so the wiring I had to do was minimal. It was mostly plug'n play.

 

[WINDSHEAR II]

Great information guys! For the record, I have decided to chuck the blown AMC 258 i6 / 4.2l and install a '94 4.0l in it's place. Just makes the most sense from a practical standpoint. From all I have read...this is a OBDI engine management system. I had planned to get that ULTRA-expensive swap over package from HESCO, but now I will try a salvage yard for the parts I need. The engine I have is complete, minus the wiring harness and flywheel. Donor vehicle was a '94 Laredo XJ with 74,000 miles.

Stephen