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Buick 3.8 V6 swap


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          Ok, son's MJ has the Chebby 2.8 v6 with the AX5 in it. We have been trying to find a camaro or firebird 3.4 v6 to swap in, 2.8 is smoking bad.  Last week, we were offered a Buick 3.8 v6 with a T5 and a 4bbl intake for free. Catch is we need to get it out of a MG, engine swap that went bad, and the engine will need a total rebuild, if it can be. The engine has been sitting with water in the cylinders for a few years.

         Since the Buick 3.8 v6 is a different beast from the chebby 3.8 v6, I think this would work. The Buick is 90* engine but uses the 60* family (2.8, 3.1, 3.4) bellhousing bolt pattern and unlike those stupid chebby engines, has the dizzy up front.

         What I am asking is if anyone has done this swap, are they still on here, and can I get pics of the engine mounts, exhaust manifolds/routing. I know the AX5 may not last behind the 3.8 so I would also like to know what  manual tranny may work for the engine and still use the jeeps transfer case. 

         If we find a 3.4 v6, we may still slap that in and use the Buick v6 for the 79 280zx engine swap.


thoughts and or pics welcome.

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To my knowledge, no one else has done the swap that I did.


I swapped in a buick 3800 series 2. This motor, to my knowledge, has a bare minimum in common with the buick 3.8 you are talking about...the bell housing bolt pattern is not even the same.



I'm sure the pics from my swap are somewhere, but I took so many, I don't have and won't make time to repair the links to them.


The reason I won't is that none of what I did would be done the same way again. From motor mounts to transmission to exhaust, it would all be changed.


I do not, in any way, think that going from a p.o.s. Carbureted system to a carbureted system that has negligible gains in horsepower and torque is worth your time.


Just because it's available, doesn't make it worth the swap. A fuel injected 3.4 will generate more power and torque, and aside from some minor wiring and re routing the intake, is completely bolt in.

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Thanks for the input JeepcoMJ, that's what I was looking for. That being said, I need to look over your thread again. See how much wiring you needed to do and what tranny/xfr case your running now. 

We would love to toss in a 3.4 with the FI. I thought folks down here would be tossing those out and swapping in V8 but they think they gold.

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The series 2 is too much work.


Its all apart right now. The trans needed is ax15 from a jeep xj or mj, with deiveshafts. Bellhousing from dodge dakota 2.5l with ax15...early 90s.


Starter is on drivers side so you still need aluminum welding skills to put a starter hump in the right spot. Not needed with 3.4, and 3.4 could be fine with an ax5


All I did for the wiring was get the complete engine bay harness, and bulkhead connectors.

Then I eliminated all the things that the jeep harness already had, or that I didnt need.

Wiring I deleted:

Abs pump and sensors


turn signals

washer pump

Windshield wipers


I piggybacked the 3800 harness to the jeep harness, and mounted the ecm above the blower motor.


Bakerelectronics.com has the VATS (Vehicle Anti-Theft System) bypass module for about $30. It needs a start+accessory hot (tag off ignition switch), ground, then blue wire runs to pin 55 on the ecm.


Worst thing needed is fuel pump wiring. I ran an inline pump on the driver's side frame rail and ran the wires down. I used the camaro relay center for all motor functions.


Also, the only wires I HAD to solder were the o2 sensor wires...mine were cut, so they may be long enough. There are 4 sensors, one on each manifold, one pre cat, one post cat.


I did the swap the last year emissions were necessary for 96 and older, when they were doing sniffer tests instead of scan ports. Used a NoX catalytic converter ($98) and had close to zero emissions.


Wired check engine light wire to the gauge cluster indicator, and put a bulb in. Mounted scan port to knee board.


The 3.4 and 3.8 use the same tachometer signal as the 2.8, so no potentiometer adjustment was necessary.

For oil pressure I teed into the port to run both the camaro and the jeep sensor.

coolant temp I had pulled the lower intake plenum off and simply drilled and tapped a second hole to put the jeep sensor in.


That was all very simple. If someone you know has alldata, they can pull diagrams.

Wiring is near identical between 3.8 and 3.4

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humm, I would really rather get the 3.4 and everything for FI and do that. I guess find a running parts car for cheep. I do like the 3.8 idea, especially if we can supercharge it or turbo, but both of those come on at higher rps correct?  JeepcoMJ, thanks for posting all that, it does help and is good info.

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The supercharged 3800 has lower compression than the n/a.


It runs throughout the rpm range consistently. You would need wieing, computers, and engine from a s/c car to go that route.


The 3.8 also has a much thicker flywheel than the 2.8, and is internally balanced...so the 2.8 can't go on without being neutrally balanced. Same goes for a newer 3.4, though.

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