3.4 in a jeep comanche

[tsgtbob]

I know this will probably get me flamed, but.........
Have any of you all put one of the RWD engines in a Heep comanche? I have a GM pattern tranny, as well as a 231J t case.
The 2.5 heep engine is about shot, and I want a little more power outta her.
The MJ is sitting on a 4 inch lift, lockers on both ends, and is used as my response vehicle for a local SAR team that I belong to.
One reason I don't have an S-10, is the IFS, plus, I like jeeps.
Oh yeah, the chassis is the '86 pre 4.0 redux. I'm stuck with the 60 deg, or the 2.5, as the 4.3 family of GM engines is too wide, plus I have to pass a visual emissions inspection. The 4.0 in this chassis is also impossable, as the firewall was moved back in '87 when the 4.0 was introduced.
Thanks, and let the flames begin

[sharkey]

RE: 3.4 in a jeep comanche

well, being the jeep came with a 2.8l, you should be able to get all the parts for a direct bolt in of a rwd 2.8, 3.1 or camaro 3.4l. the 3.4l is a pretty good engine, 160hp. gm also has a 3.4l ht crate engine that is basicly a warmed over 3.4l camaro motor.

the next question is, do you want a carb or efi??? the efi isnt that hard to do, no matter what engine you put in. if you get a complete 3.4l engine, get the wiring harness and ecm from the car (make sure the car is a standard, the auto is electronicly controlled) and throw it in. if you do a 2.8 or 3.1l, same deal. you will also need to get a high presure fuel pump and run the fuel lines for it, and moddify your tank (could probobly get newer 4.0l efi tank and lines and just mod the lines at the fuel rail).

now if you go carb, its a whole lot easier, just bolt it on and go. however, the benifits of efi have been proven many times, on and off road.

[tsgtbob]

Originally the comanche that I am looking to do has a 2,5 AMC engine in it. I have a 904 with the GM 60 degree bell patteren, so I was looking to do that. I do have a concern about the intake for the 3.4 not having enough room behind the radiator, as well as a the computer wiring harness issues. I just got done helping a friend put a 4.3 in a wrongler, and the wiring was a nightmare!!!!! Even with the assistance of BOTH FSMs, there were still gremlins in the system. The fuel issue that we ran into in that swap was that the Jeep fuel pump puts out too high a pressure, which constantly flooded the engine. A carb is NOT an option, as this thing sees some really weird angles and situations. Having it die on a wicked downhill is not an option!!!!!
This project might just turn into a long term thing, patch the 2.5 together (it spun several bearings, both rod and main, and I have another crank) then acquire the pieces parts and jazz to put a 3.4 in it.

[geoffinbc]

Put in a 3.4L with TBI injection. Fits like carb would and even uses the same air cleaner. You get rock solid reliability (thats why they make conversion kits for jeeps to use GM TBI) and easy troubleshooting and maintainence.

Go ahead snoop around>> http://members.shaw.ca/betterthanyou/eng.htm

[tsgtbob]

Cool. Nice clean install. I want the EFI, as injection handles weird attitudes of (semi) extreme wheeling MUCH better than a carb. As it sits right now, I'm just gonna keep the 2.5 for the summer, and collect the parts needed for a swap over the winter. that will asloo let me refreshen the tranny, and T-case before I REALLY start to abuse them.
Thanks for the good info. Now I just need to get the 2.8 celebrity done.....

[geoffinbc]

EFI will run up-side-down. But too bad the oil pump wont

[WhiteRaider]

You might want to consider running a Megasquirt computer rather than a stock computer. If you have a manual xmission or a non electric auto, it would make your wiring chores very easy.

I doubt that you'd have a problem with a 660. Some guys with Mitsubishi Monteros and Dodge Raiders have put 4.3l engines in them without moving the radiator and just ran electric fans. The 3100 or 3400 would be even smaller than them. You wouldn't be able to install a Jeep 4.0 in them without moving the radiator forward.

The easiest solution with some great gain would be a RWD camaro 3.4l engine with the HT crate engine cam installed. The HT cam will give your torque at lower RPMs which is nice when you're 4wheeling.

You might want to check out 4x4wire.com and look through the Isuzu section. Some of the earlier Isuzus had 2.8l GM engines and they have done quite a few swaps to 3.4ls. They would be a good wealth of information on the 4x4 specific aspects of the swap. One of the Isuzu guys sent me a boatload of info that I'd be happy to forward onto you. Just PM me with your email address.

I'm just starting to try and put a FWD 3100 in my 4x4 so, if you aren't going to do something soon, I may have some good information for you in a month or so.

Cheers!

[WhiteRaider]

Oh, if you're going to replace your tranny, you can use an AX15 or an NV3550 on the 660! I just bought an ax15 for mine. You have to get a bellhousing from a 96-99 Dodge Dakota 4cyl manual transmission - use the clutch fork, master and slave cyl from the Dakota as well. Get a clutch plate from a 1994 Chevy Camaro 2.4l with a 4 speed manual and buy an Advanced Adapters pilot busing for the NV4500 conversion or the Novak Conversions bushing. I'll be doing that exact combo on my swap. I'm not sure whether to use a 231 or a 242 xfer case - probably whatever I can find w/low miles that's cheap.

Cheers!