Join Date: Sep 1999
Location: Philadelphia, Pa.
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Re: 2.5L to 2.8L swap need info, please!
A couple of points to remember here:
1) All things being equal, the 4.0 would definitely be the engine to go to. However, in 1984-86 XJ and MJ (Comanche) bodies, the firewall would have to be trimmed significantly for an in line 6 cylinder engine to fit. Jeep modified the body in 1987 for the 4.0 to fit in there.
2) I have a 1986 Cherokee with the 2.8L, TF904 and NP 207 transfer case, so yes, the 2.8 will mate to them....However, you might need to replace the 2.5L flex plate with one for the 2.8 because the 2.8 is an externally balanced engine.
3) My 2.8 has been very reliable over the 15 years that I've owned my Jeep. That being said, the carbureted 2.8 is more powerwise like a typical 4 cylinder engine. It definitely will give you more power/torque than the carbed 2.5 did and it is about equal in that respect to the TBI 2.5. It is true, early versions of the 2.8 had oil leak troubles; they featured two piece rope rear main seals and their crankshaft bearing journals were undersized. In late 1985, Cheverolet introduced the one piece main seals and larger journals. My advice would be to get a 2.8 that is 1986 or later.
4) The XJ 2.8 engines are all carbureted (probably GM didn't care to sell AMC the more powerful TBI engine; would you sell a more powerful version to your competitor??[img]/wwwthreads_images/icons/smile.gif[/img]); they have the Rochester 2SE or E2SE (California models) carbs. You could also swap in a 3.4L V-6 from a 93-95 Camaro but thse engines are fuel injected. To install any kind of fuel injection for the 3.4 or the 2.8, the XJ wiring would have to be modified and a electric fuel pump installed. You would get more power for sure but OTOH, the carbed 2.8 will fit right where the 2.5 was. I'm not sure if you can use the S-10 exhaust manifolds in the Jeep, though.