3 Engine swap options

[marcial88]

I own an 86 Comanche X 4x4 with the dreaded 2.8L V6 automatic A904 transmission not running 

I came across someone selling a early 2.5L AMC along with the transmission and everything needed for the swap for $1,200. 

Another option is the 3.4L Camaro engine swap and around here I can find stick or auto Camaro for around the same price. 

Another option is the LS swap and I think it's more work and money. 

I would like to do the 2.5L but I would like to swap in an automatic transmission into it but information is very limited. 

With the 3.4L, everyone says it's a simple swap. But when it comes down to it I haven't found a straight answer when it comes to getting an standard version of the 3.4 or an automatic version of it. Some people say if your 86 is an automatic get an automatic Camaro same if it's stick. Then the flywheel getting balanced. Does the flywheel or flexplate need to get balanced if it's an automatic 3.4? I'm not sure. Another issue is that it's recommended to get a manual Camaro because the manual computer won't put your comanche in limp mode and the check engine light will work if there are any issues. 

With the LS it's not a straight forward job I know I'll need mounts, transmission, cross member, front/rear drive shaft, radiator and everything starts to add up and gets pricey. 

What do you guys think? I was talking to a Jeep mechanic and he said anything can be done. He said with the 2.5, it's a good option but there is little to no informationor support regarding swapping in an automatic transmission. 

With the 3.4L he said he's never done a 3.4 swap but said if you're going to go through the trouble of swapping engines might as well spend the extra money to do an LS swap. He said you can find a 5.3 anywhere for cheap. Junk yards have them for cheap and people on Facebook and offer up have them for cheap even the transmission are everywhere. 

What do you guys think? 

How easy and what do I need to do 2.5L swap?

For the 3.4L I would need someone to tell me if I want to keep it automatic I would need this part from an automatic and this part from a manual. 

And for the LS I know the easy part is getting a 5.3/4.8/6.0 is the easy part for me. The way I see it is drop it in and and get it running then deal with the hood clearance and looking for accessories mounts after. 

[The86manche]

To do the 2.5 I could imagine you'd have to consider droveshaft length, you would need the mj fuel pump and the wiring for the tbi(or efi) drivetrain

Imo id say it would be easier to drop in the 3.4. Since you have the 904 the 3.4 bolts right to it. I believe the flex plate would have to be neutral balanced. And you can take the intake off your 2.8 and drop it onto your 3.4. Or go with an edelbrock intake. As for fuel supply you would just have to run an inline fuel pump on a key on accessory in your fuse block.

If you want to get technical you could keep the efi of the 3.4 and run an independent efi setup. 

[The86manche]

I have paperwork from a conversion that was done to my truck that tells all you need for the 3.4 swap.

[89 MJ]

What are your plans for the truck in the long term? That should dictate the route you go. 

[coheed]

There's also the option of getting an auto Camaro and getting an adapter from Novak to run a Jeep transfer case on the back of the 4l60e if you want a transmission with overdrive. That's the route I'm going. The Novak kit includes all the parts necessary to keep the factory Camaro PCM to run the engine and control the transmission. The 93 Camaros can also be found with the 3.4 and the 4l60 with no e, meaning that it's not electronically controlled, so less wiring would be necessary.

[The86manche]

3 hours ago, coheed said:

There's also the option of getting an auto Camaro and getting an adapter from Novak to run a Jeep transfer case on the back of the 4l60e if you want a transmission with overdrive. That's the route I'm going. The Novak kit includes all the parts necessary to keep the factory Camaro PCM to run the engine and control the transmission. The 93 Camaros can also be found with the 3.4 and the 4l60 with no e, meaning that it's not electronically controlled, so less wiring would be necessary.

You can also find a 700r4 as well and that wouldn't require an adaptor. Just a 205 tcase

[Greenjeans]

If you can’t sleep tonight, you may want to read through my thread on the “Other cool projects board”.

I did the 3.4 swap into an XJ.  If your 2.8 carb is good, the rest of it is pretty straight forward.  My original carb was junk so I bought a Weber before I knew about the 3.4 option and so I used the new carb and 2.8 intake on the 3.4.  You can swap your other 2.8 parts over to the 3.4 and drop it in.  As mentioned, you have to install an electric fuel pump as the 3.4 has no provision for a mechanical fuel pump.  I have 3k miles on my swap now and I’m very happy with it.

 

i used a 700r4 from an ‘88 S-10 blazer and a 241C transfer case from a full size Chevy pickup.

[Tex06]

On 6/6/2025 at 6:52 PM, The86manche said:

You can also find a 700r4 as well and that wouldn't require an adaptor. Just a 205 tcase

700r4 and 4L60 are the same transmission, GM changed their nomenclature in the early 90s on how they name them. Most parts interchange. 

 

4L60e is a different animal though due to the electronic controller. 

 

Also I know in Fieros of the same vintage ('86-'88) you can swap the GM 2.8L to the 3.4L and keep the 2.8L ecu to run the bigger motor. You don't get all the power from it but it will run well, so that may be an option.

[The86manche]

3 hours ago, Tex06 said:

700r4 and 4L60 are the same transmission, GM changed their nomenclature in the early 90s on how they name them. Most parts interchange. 

 

4L60e is a different animal though due to the electronic controller. 

 

Also I know in Fieros of the same vintage ('86-'88) you can swap the GM 2.8L to the 3.4L and keep the 2.8L ecu to run the bigger motor. You don't get all the power from it but it will run well, so that may be an option.

You are correct, I wasn't aware of the name change until recently when I saw a post on Facebook talking about them haha