When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
So I bought my Cherokee about 3 years ago when I was a junior in Highschool it seemed good at the time but I had no clue what I was getting into, it ran and drove but on the way home the transmission went out. The guy that sold it gave me a second tranny with it (big red flag) but unfortunately when I pulled the tranny out to swap it it was not even a close match, so I ended up rebuilding the transmission myself and that went very well, it seems to work great and I've put probably 300 to 500 miles on it so far, when I put it back up I removed the vacuum lines for the 4x4 drive and hi lo gears, but I have that covered and I'm going to fab a mechanical system for it because I just don't like the vacuum. NOW the engine, It's the 2.8L V6 and if I would've known I wouldn't have bought it. It runs ok and I've done some minor tune up on it, I rebuilt the carb and changed oil but Its burning oil and I just don't like the way it runs. I kinda want to do a swap. I've read a lot of forums and info pages and I'm thinking to do the GM 3.4L V6. I don't really want to grab one from a junk yard because it could be hit or miss but I also don't want to drop $2500 or more for a refurbished long block, but I'd prefer that option. I want to keep it carbureted and maybe put a nice edelbrock on it. So 2 questions, 1 if I did do the long block what intake can I use? I can't find a thing about a carb intake for the 3.4L/207 engine, or can I use the one off the 2.8 but then swap the carb? 2 could I do a rebuild of the 2.8L and swap the cam shaft, heads, and lifters etc. but use the 2.8L block and end up with a 3.4L? In my reading that seemed possible. I really don't know much about engines and this would be my first rebuild so take that into account, please help me if you can!
I guess your sticking with the GM V6 so you can use the same transmission? Is that the Chrysler A904? ... Interesting choice wanting to stick with a carbureted engine too. If you were willing to go fuel injected it would certainly broaden your options.
As for your 2 questions...
1 - If the intake manifold bolt patters are the same they should be interchangeable. According to the internet (that is never wrong) they should cross compatible on the intake bolting on. But whether or not your carburetor would be jetted correctly for the larger displacement engine is the next question. You may have to look into a Edelbrock or Holly that has all the jet options to get it tuned for your setup.
2- I'm no GM V6 know it all - but I don't hear good things about the 2.8L V6.. The bore and stroke on the 2.8 are different than the 3.4 so without serious boring and a crank swap you'll have a hard time getting a 3.4 out of the 2.8... I would try to obtain the 3.4 and make it work.
I guess your sticking with the GM V6 so you can use the same transmission? Is that the Chrysler A904? ... Interesting choice wanting to stick with a carbureted engine too. If you were willing to go fuel injected it would certainly broaden your options.
As for your 2 questions...
1 - If the intake manifold bolt patters are the same they should be interchangeable. According to the internet (that is never wrong) they should cross compatible on the intake bolting on. But whether or not your carburetor would be jetted correctly for the larger displacement engine is the next question. You may have to look into a Edelbrock or Holly that has all the jet options to get it tuned for your setup.
2- I'm no GM V6 know it all - but I don't hear good things about the 2.8L V6.. The bore and stroke on the 2.8 are different than the 3.4 so without serious boring and a crank swap you'll have a hard time getting a 3.4 out of the 2.8... I would try to obtain the 3.4 and make it work.
yeah i did a little more research and doing the 2.8 rebuild is a silly idea, I think im going to go with the swap, and I realized edelbrock does carbs mostly for V8s so I'll probably go with a holly. I have the A999 which is same bolt pattern as the A904 so all good there and yes thats why I want to stick with the V6 so I can keep the transmission. The reason for not doing fuel injection is just because im not sure about the computer I really like being able to turn it down if its too rich etc. But I'd be interested in fuel injection if I can easily change computer settings for thing but I don't kniw if thats even possible. What do you think?
You might get by with the oem carb but you would want to take it to a shop that does carb tuning. They can use little micro drill bit to open the jets up until it runs better. This service may cost as much as the replacement engine though. Kind of a headache too.
What I think?...
If you find a 3.4 V6 from a doner vehicle - get the entire wiring harness and all computer boxes to go with it. You would basically be replicating its original environment but smacking into a jeep. You'd run into plenty of little issues, like the sensors that communicate with you gauge cluster may not be the right ones and give you artificially high or low readings. The Jeeps original electrical system having to coexist with the engines dedicated system. But I think it can be done. It would be a lot of work, time, money, .. it would be a full blown "project" jeep that gets worked on more than driven.. For a while anyways.
The thing is, all those older year jeeps and even GM motors were just low power and slow. Which might be just fine. But you could probably save yourself a lot of work and maybe even money too... if you just let this jeep go and find one with the 2.5 or the 4.0.. Or see if any scrap yards have engine and transmission out of a roll over vehicle available and you can swap that in.
You might get by with the oem carb but you would want to take it to a shop that does carb tuning. They can use little micro drill bit to open the jets up until it runs better. This service may cost as much as the replacement engine though. Kind of a headache too.
What I think?...
If you find a 3.4 V6 from a doner vehicle - get the entire wiring harness and all computer boxes to go with it. You would basically be replicating its original environment but smacking into a jeep. You'd run into plenty of little issues, like the sensors that communicate with you gauge cluster may not be the right ones and give you artificially high or low readings. The Jeeps original electrical system having to coexist with the engines dedicated system. But I think it can be done. It would be a lot of work, time, money, .. it would be a full blown "project" jeep that gets worked on more than driven.. For a while anyways.
The thing is, all those older year jeeps and even GM motors were just low power and slow. Which might be just fine. But you could probably save yourself a lot of work and maybe even money too... if you just let this jeep go and find one with the 2.5 or the 4.0.. Or see if any scrap yards have engine and transmission out of a roll over vehicle available and you can swap that in.
Awesome advice thanks! I think if I'm going to do the swap it'll be a lot easier and simple to stick with the carb, I know how to tune them so I should be good there. I just need to get it to be a reliable car I can use for college, then I'll work on it off and on for a while and maybe at a later point switch to fuel injection. I've tried to sell it but no one is interested, I could scrap it for $250 but it seems a waste since I rebuilt the transmission, it might be an fun project. I'll post updates and pictures as I go so as to be helpful in case anyone else is doing the same thing.
Thanks for the reminder. Ill fix that right away.
The engine went to a guy replacing a worn out 2.8.
In a nutshell any 2.8 still running is either a late 2.8 or has the improved gaskets.
3.4 is the beefed up and vastly improved in every way ultimate evolution of 2.8 line.
If carburetor is a deal breaker then throttle Body Injection system including the manifold sourced from EFI 2.8 Blazer, S10 fits the 3.4 and works. It's been done plenty of times.
So I bought my Cherokee about 3 years ago when I was a junior in Highschool it seemed good at the time but I had no clue what I was getting into, it ran and drove but on the way home the transmission went out. The guy that sold it gave me a second tranny with it (big red flag) but unfortunately when I pulled the tranny out to swap it it was not even a close match, so I ended up rebuilding the transmission myself and that went very well, it seems to work great and I've put probably 300 to 500 miles on it so far, when I put it back up I removed the vacuum lines for the 4x4 drive and hi lo gears, but I have that covered and I'm going to fab a mechanical system for it because I just don't like the vacuum. NOW the engine, It's the 2.8L V6 and if I would've known I wouldn't have bought it. It runs ok and I've done some minor tune up on it, I rebuilt the carb and changed oil but Its burning oil and I just don't like the way it runs. I kinda want to do a swap. I've read a lot of forums and info pages and I'm thinking to do the GM 3.4L V6. I don't really want to grab one from a junk yard because it could be hit or miss but I also don't want to drop $2500 or more for a refurbished long block, but I'd prefer that option. I want to keep it carbureted and maybe put a nice edelbrock on it. So 2 questions, 1 if I did do the long block what intake can I use? I can't find a thing about a carb intake for the 3.4L/207 engine, or can I use the one off the 2.8 but then swap the carb? 2 could I do a rebuild of the 2.8L and swap the cam shaft, heads, and lifters etc. but use the 2.8L block and end up with a 3.4L? In my reading that seemed possible. I really don't know much about engines and this would be my first rebuild so take that into account, please help me if you can!
The 2.8 60 degree V6 was a good engine...with a flaw..
The failure mode went like this.
1. Eventually the water pump front seal would wear out and start loosing coolant.
2. The owners didn't notice until the engine overheated.
2.1 A new water pump and back in business right ? Not quite.
During the overheat event the heads and intake manifold got wonky and the coolant sealing part of the gaskets became compromised. Slowly the coolant would leak into the lifter valley and into the crank case in noticed.
Oil and coolant don't mix and when forced together they don't lubricate either.
3. if the intake gaskets weren't replaced with the water pump... the cam bearings would go first and the pressure in the oiling sutem would drop.
4. The crank bearings would follow shortly after.
Improved gaskets were invented. That's all you can get since then but by the then the reputation was established.
The 2.8 was steadily improved but.. reputation.
The 3.4 is the super duper ultimate evolution of the 2.8 60 degree V6 family.
If a 2.8 is still running the chances are pretty good it's got the improved gaskets. If not, or not sure, they're easy enough to install for prevention and peace of mind.
The 3.4 from a Front Wheel Drive Camaro or Firebird drops in and bolts up but there's two things needed to get it to run.
Induction.
For induction the hot lick is to raid the intake manifold and TBI system out of a 2.8 Blazer or Jimmy and transplant it in its entirety.
OR
Swap your 2.8 manifold onto the 3.4 and pick your carb and electric fuel pump. Why electric ? Because fuel pump boss on the 3.4 isn't machined for a fuel pump as was the 2.8. Also the cam doesn't have the fuel pump drive lobe like the 2.8 cam.
The 3.4 swap is a nice bump in power and a good way to get or keep a V6 Cherokee going with out having to replace every drivetrain componant from the radiator back like a 4.0 or 4.3 swap. It's also an inherently smoother running engine.
1985 Cherokee Engine Build
