2.8 to 3.4 swap
01-16-2009, 04:02 PM
#1
Junior Member
Thread Starter
Join Date: Nov 2008
Posts: 52
Likes: 0
Received 0 Likes
on
0 Posts
Year: 1985
Model: Cherokee
Engine: 2.8 V6
2.8 to 3.4 swap
Does anybody know just how easy the engine swap from a 2.8 to a 3.4 is. I cant seem to find a write up anwhere on the web. Please help.
01-16-2009, 05:07 PM
#6
CF Veteran
Join Date: Oct 2008
Location: Hell, CA
Posts: 2,127
Likes: 0
Received 2 Likes
on
2 Posts
Year: 1989
Model: Cherokee
Engine: 4.0L I6
Well, as far as GM vehicles go the 3.4L Is basically a direct replacement for 2.8's. You shoudl be able to swap your parts from your 2.8 over and drop it in. That is unless you want to switch to MPFI vs your carb/TBI setup
Trending Topics
01-17-2009, 04:57 AM
#8
CF Veteran
Join Date: Mar 2008
Location: South Side Chicago
Posts: 2,088
Likes: 0
Received 2 Likes
on
2 Posts
Year: 1992, 2- 1998 (All 3, 4 Doors)
Model: Cherokee
Engine: 4.0L in all
Depends what year the 2.8 AND the 3.4 is.
Old 2.8's are carb engines until around like 84 or 85.
Then they went to a TBI set up for a little while.
Then to a MPFI.
There's a weird section in GM production where they had RWD and FWD 60*'s running around out there...
Most of the 3.x engines are all MPFI. Some OBD-I, Most OBD-II.
And whatever you do, STAY AWAY FROM THE BUICK 3.8L. That thing is just plain crap.
For what it's worth, I'd go with a 90* V-6, instead of a 60*, There are WAY more kits/parts available to swap a SBC into anything than one of those. (And yes, the 4.3 is the "Baby SBC" or "3/4 SBC", Same damn everything, just 2 cylinders missing.)
Plus 4.3's are already RWD engines, GM put them in damn near everything, from EVERY truck they made to Full Size cars.
Old 2.8's are carb engines until around like 84 or 85.
Then they went to a TBI set up for a little while.
Then to a MPFI.
There's a weird section in GM production where they had RWD and FWD 60*'s running around out there...
Most of the 3.x engines are all MPFI. Some OBD-I, Most OBD-II.
And whatever you do, STAY AWAY FROM THE BUICK 3.8L. That thing is just plain crap.
For what it's worth, I'd go with a 90* V-6, instead of a 60*, There are WAY more kits/parts available to swap a SBC into anything than one of those. (And yes, the 4.3 is the "Baby SBC" or "3/4 SBC", Same damn everything, just 2 cylinders missing.)
Plus 4.3's are already RWD engines, GM put them in damn near everything, from EVERY truck they made to Full Size cars.
Last edited by BowtieGuy3; 01-17-2009 at 05:02 AM.
01-17-2009, 12:44 PM
#10
Senior Member
Join Date: Sep 2008
Location: Sioux Falls, SD
Posts: 897
Likes: 0
Received 12 Likes
on
9 Posts
Year: 1999
Model: Cherokee(XJ)
Engine: 4.0L
I was going to do the swap on my '86 XJ, but I sold it. Anywho, find a 3.4 from any early 90s Camaro, S-10 etc. Fuel injection is OK. Remove the intake on the new motor along with any accessories and the front timing cover. Replace the front cover with your 2.8 cover and accessories. You will probably need to change the harmonic balancer from your 2.8 to the 3.4 too. No biggie. Swap over your intake manifold and carb setup to the new engine. Install in XJ. Done.
Google for 2.8 to 3.4 swap. Some guy did it in a day or so by simply unbolting all the XJ stuff in the Jeep, pulling the block and dropping in the new block and aligning all the stuff back up and bolting on. I was VERY tempted to do it, but I ended up trading my '86 in to a dealer for a down payment on my '99.
Google for 2.8 to 3.4 swap. Some guy did it in a day or so by simply unbolting all the XJ stuff in the Jeep, pulling the block and dropping in the new block and aligning all the stuff back up and bolting on. I was VERY tempted to do it, but I ended up trading my '86 in to a dealer for a down payment on my '99.
01-17-2009, 02:52 PM
#11
CF Veteran
Join Date: Nov 2008
Posts: 2,003
Likes: 0
Received 4 Likes
on
3 Posts
Year: 1987
Model: Cherokee
Engine: 4.0
I completely disagree with diskman.
DO NOT put the 2.8 liter intake or carbeurator on. they are at least half your problem anyways.
for the swap you need a 1990 to 1995 camaro or firebird engine.
try and find one that's already got the same trans setup as yours (i.e. if you have auto, try and find one from an auto, manual find one from a manual) because otherwise you have to have the 2.8's flywheel neutrally balanced by a machinest. this is because the 3.4 is internally balanced, the 2.8 is not.
you can directly swap the 2.8 motor mounts (though you may have to tap a hole on the block), starter, and exhaust manifolds to the 3.4.
you need to put the 2.8 liter oil pan on the 3.4 to clearance the front axle. check this out, you may not need to swap the timing cover. this is up in the air though, some guys say they need to put the 2.8 timing cover on, other's say they don't. IIRC y ou can cut the 3.4 liter timing cover seal down flush then use a 2.8 liter oil pan gasket (get the nice blue rubber one)
you can use a 2.8 liter FULL CORE radiator for the swap. I would eliminate any air conditioner condensor or lines you have, as well as the a/c pump on the motor (if it has one) because you may have to notch the frame to get the a/c pump to fit.
then relocate the radiator as far forward as you can (you can move it forward about 2" on it's mount).
from here it will bolt in. you will need to devise your own intake assembly, but that's fairly simple and straightforward. you will need the entire engine bay harness and having the dash harness is always nice so you can use the firewall connectors to extend what wires may need to be extended.
the wiring is straightforward. you need to basically trail wires and eliminate what you won't need. remember, this is what you call a piggyback system. it will run along with your factory wiring harness, so all you need from the 3.4's wiring harness is that which pertains to the engine operation. basically remove the headlights, heater core fuses, etc. but keep the e-fan relay and wiring so you can run a nice electric fan.
then the last thing you need is a Vehicle Anti-Theft System (VATS) bypass module from bakerelectronix. this supplys 55 hz (I believe it's hz) to pin number 55 on the engine computer and enables the injectors to ground when the ignition is on. this bypasses the coded keys so you won't have to figure out how to make the ignition work in your mj. The engine computer is located in the engine bay, on the passenger side rear firewall.
the ONLY way to drop a motor from a camaro is to drop the entire front suspension out and lower it on the crossmember/lift the car off of it FYI.
there is tons of info in google on this swap
and if you want a similar swap that blows the doors off of a 4.3 and 2.8 and eats inline 4.0's for breakfast, try the camaro 3800 (and then you'll really have a swap to ***** about)
DO NOT put the 2.8 liter intake or carbeurator on. they are at least half your problem anyways.
for the swap you need a 1990 to 1995 camaro or firebird engine.
try and find one that's already got the same trans setup as yours (i.e. if you have auto, try and find one from an auto, manual find one from a manual) because otherwise you have to have the 2.8's flywheel neutrally balanced by a machinest. this is because the 3.4 is internally balanced, the 2.8 is not.
you can directly swap the 2.8 motor mounts (though you may have to tap a hole on the block), starter, and exhaust manifolds to the 3.4.
you need to put the 2.8 liter oil pan on the 3.4 to clearance the front axle. check this out, you may not need to swap the timing cover. this is up in the air though, some guys say they need to put the 2.8 timing cover on, other's say they don't. IIRC y ou can cut the 3.4 liter timing cover seal down flush then use a 2.8 liter oil pan gasket (get the nice blue rubber one)
you can use a 2.8 liter FULL CORE radiator for the swap. I would eliminate any air conditioner condensor or lines you have, as well as the a/c pump on the motor (if it has one) because you may have to notch the frame to get the a/c pump to fit.
then relocate the radiator as far forward as you can (you can move it forward about 2" on it's mount).
from here it will bolt in. you will need to devise your own intake assembly, but that's fairly simple and straightforward. you will need the entire engine bay harness and having the dash harness is always nice so you can use the firewall connectors to extend what wires may need to be extended.
the wiring is straightforward. you need to basically trail wires and eliminate what you won't need. remember, this is what you call a piggyback system. it will run along with your factory wiring harness, so all you need from the 3.4's wiring harness is that which pertains to the engine operation. basically remove the headlights, heater core fuses, etc. but keep the e-fan relay and wiring so you can run a nice electric fan.
then the last thing you need is a Vehicle Anti-Theft System (VATS) bypass module from bakerelectronix. this supplys 55 hz (I believe it's hz) to pin number 55 on the engine computer and enables the injectors to ground when the ignition is on. this bypasses the coded keys so you won't have to figure out how to make the ignition work in your mj. The engine computer is located in the engine bay, on the passenger side rear firewall.
the ONLY way to drop a motor from a camaro is to drop the entire front suspension out and lower it on the crossmember/lift the car off of it FYI.
there is tons of info in google on this swap
and if you want a similar swap that blows the doors off of a 4.3 and 2.8 and eats inline 4.0's for breakfast, try the camaro 3800 (and then you'll really have a swap to ***** about)
11-07-2009, 01:05 AM
#12
Newbie
Join Date: Sep 2009
Location: wilkeson
Posts: 14
Likes: 0
Received 0 Likes
on
0 Posts
Year: 87
Model: Cherokee
Engine: 4.3 vortec
Depends what year the 2.8 AND the 3.4 is.
Old 2.8's are carb engines until around like 84 or 85.
Then they went to a TBI set up for a little while.
Then to a MPFI.
There's a weird section in GM production where they had RWD and FWD 60*'s running around out there...
Most of the 3.x engines are all MPFI. Some OBD-I, Most OBD-II.
And whatever you do, STAY AWAY FROM THE BUICK 3.8L. That thing is just plain crap.
For what it's worth, I'd go with a 90* V-6, instead of a 60*, There are WAY more kits/parts available to swap a SBC into anything than one of those. (And yes, the 4.3 is the "Baby SBC" or "3/4 SBC", Same damn everything, just 2 cylinders missing.)
Plus 4.3's are already RWD engines, GM put them in damn near everything, from EVERY truck they made to Full Size cars.
Old 2.8's are carb engines until around like 84 or 85.
Then they went to a TBI set up for a little while.
Then to a MPFI.
There's a weird section in GM production where they had RWD and FWD 60*'s running around out there...
Most of the 3.x engines are all MPFI. Some OBD-I, Most OBD-II.
And whatever you do, STAY AWAY FROM THE BUICK 3.8L. That thing is just plain crap.
For what it's worth, I'd go with a 90* V-6, instead of a 60*, There are WAY more kits/parts available to swap a SBC into anything than one of those. (And yes, the 4.3 is the "Baby SBC" or "3/4 SBC", Same damn everything, just 2 cylinders missing.)
Plus 4.3's are already RWD engines, GM put them in damn near everything, from EVERY truck they made to Full Size cars.
finding a rolled 94 blazer powerd by a 4.3 vortec auto 700r4 ?203 Tcase? "not shar on the Tcase"
the trany bolt points are the same as the ones on the comanches and cherokees. the motor mounts are harder. I cut out the old ones from the blazer after welding a 2' peace of angel to the frame rail I fabed the old mounts to the 2'x2' angel just to give it that much more. The radiator and front clip are from a 4.0l jeep cherokee i am using 1/2 of the old AC cooler for a oil cooler "4.3 needs a oil cooler." the front drive line is the same langth but not the same u joints, i made my own.
the wiring is the part that is giving me a hard time as i am color blind as heck " its my wife's fault, she wont stand there and tell me what color the wire is"
i might just bey a carb and intake to bolt on the 4.3 as the 700r4 trany has its own computer on it. i dont know yet
Last edited by comanchetrip; 11-07-2009 at 01:14 AM.
11-07-2009, 01:52 AM
#13
CF Veteran
Join Date: Nov 2008
Posts: 2,003
Likes: 0
Received 4 Likes
on
3 Posts
Year: 1987
Model: Cherokee
Engine: 4.0
Depends what year the 2.8 AND the 3.4 is.
Old 2.8's are carb engines until around like 84 or 85.
Then they went to a TBI set up for a little while.
Then to a MPFI.
There's a weird section in GM production where they had RWD and FWD 60*'s running around out there...
Most of the 3.x engines are all MPFI. Some OBD-I, Most OBD-II.
And whatever you do, STAY AWAY FROM THE BUICK 3.8L. That thing is just plain crap.
For what it's worth, I'd go with a 90* V-6, instead of a 60*, There are WAY more kits/parts available to swap a SBC into anything than one of those. (And yes, the 4.3 is the "Baby SBC" or "3/4 SBC", Same damn everything, just 2 cylinders missing.)
Plus 4.3's are already RWD engines, GM put them in damn near everything, from EVERY truck they made to Full Size cars.
Old 2.8's are carb engines until around like 84 or 85.
Then they went to a TBI set up for a little while.
Then to a MPFI.
There's a weird section in GM production where they had RWD and FWD 60*'s running around out there...
Most of the 3.x engines are all MPFI. Some OBD-I, Most OBD-II.
And whatever you do, STAY AWAY FROM THE BUICK 3.8L. That thing is just plain crap.
For what it's worth, I'd go with a 90* V-6, instead of a 60*, There are WAY more kits/parts available to swap a SBC into anything than one of those. (And yes, the 4.3 is the "Baby SBC" or "3/4 SBC", Same damn everything, just 2 cylinders missing.)
Plus 4.3's are already RWD engines, GM put them in damn near everything, from EVERY truck they made to Full Size cars.
the buick 3800 is one of the best v6's out there, with more power than a 4.0 by far, and easily modified, plus bolt-on supercharger setups with computers etc. readily available at junkyard prices. they are reliable, regularly making it to 300,000 miles. if you want a v6, DON'T get a shotty designed v8 that has 2 cylinder schopped off and the crank rotated a bit. if you're going with a 4.3, put in a v8. it's the same darn brackets, exhaust routing, radiator, and hardly takes up more room than a 4.0 lengthwise. but DON'T GET A VORTEC unless you are OK with replacing fuel and vacuum lines running under the plenum regularly.
on top of that, there was NEVER a jeep with a fuel injected 2.8 liter gm v6. it remained carbeurated through the end of it's life span @ jeep.
Last edited by JeepCoMJ; 11-07-2009 at 01:58 AM.
11-07-2009, 03:27 AM
#14
Member
Join Date: May 2009
Location: Colorado
Posts: 103
Likes: 0
Received 0 Likes
on
0 Posts
Year: 1989
Model: Cherokee
Engine: 4.0 OHV I6 (Renix)
what is in red proves you're pretty much not that intelligent.
the buick 3800 is one of the best v6's out there, with more power than a 4.0 by far, and easily modified, plus bolt-on supercharger setups with computers etc. readily available at junkyard prices. they are reliable, regularly making it to 300,000 miles. if you want a v6, DON'T get a shotty designed v8 that has 2 cylinder schopped off and the crank rotated a bit. if you're going with a 4.3, put in a v8. it's the same darn brackets, exhaust routing, radiator, and hardly takes up more room than a 4.0 lengthwise. but DON'T GET A VORTEC unless you are OK with replacing fuel and vacuum lines running under the plenum regularly.
on top of that, there was NEVER a jeep with a fuel injected 2.8 liter gm v6. it remained carbeurated through the end of it's life span @ jeep.
the buick 3800 is one of the best v6's out there, with more power than a 4.0 by far, and easily modified, plus bolt-on supercharger setups with computers etc. readily available at junkyard prices. they are reliable, regularly making it to 300,000 miles. if you want a v6, DON'T get a shotty designed v8 that has 2 cylinder schopped off and the crank rotated a bit. if you're going with a 4.3, put in a v8. it's the same darn brackets, exhaust routing, radiator, and hardly takes up more room than a 4.0 lengthwise. but DON'T GET A VORTEC unless you are OK with replacing fuel and vacuum lines running under the plenum regularly.
on top of that, there was NEVER a jeep with a fuel injected 2.8 liter gm v6. it remained carbeurated through the end of it's life span @ jeep.
If you're determined to stick with GM options, I couldn't agree more about the quality of the Buick V6. (Keep in mind that the CJ's "Dauntless" 225 V6 in the 1960s was basically an ancestor of the current 3800, which speaks volumes about its worth on the trail.) There's plenty of rear-drive-ready versions out there - check any G-body GM car from the 1980s, you'll find one eventually (maybe even the bigger 4.1/252 version!).
The 3.8/231 has tons of performance parts available, is easily expanded to just over 4.0 liters if desired, and is readily adaptable to forced induction (either turbo or supercharger). Besides that, they're almost bulletproof - how many old GM midsizers do you still see on a daily basis with this same engine, and hundreds of thousands of miles on the clock?
The 60-degree V6 (2.8, 3.1, 3.4, or "that piece of crap in the older XJ's"), on the other hand, was designed and built on the cheap from the very beginning. Food for thought: GM still uses variants on that design (the current 3.5 and 3.9 V6 engines), but most of them are now built in China. Make of that what you will...
In an early (pre-'87) XJ, I'd probably pick a four-cylinder with a stick over any version of the 2.8. Slower, yes, but much less hassle and a lot more interchange with the later 4.0 six. And now there's even a turbo kit available...
11-07-2009, 04:39 AM
#15
CF Veteran
Join Date: Nov 2008
Posts: 2,003
Likes: 0
Received 4 Likes
on
3 Posts
Year: 1987
Model: Cherokee
Engine: 4.0
I've got an 86 comanche that I put a 96 series 2 buick 3800 that is bored .030, with a competition cam. the ONLY thing i've had go wrong with it is that it sucked something into the #3 connecting rod bearing and chewed up the bearing...but 30 miles driving on it knocking (had no choice) and it didn't throw the rod, and the bearing never spun. I presume that the builders of the engine (I got it with 20k on it in a totalled out but built up F body) did not replace the oil pump when the built it, or some debris got knocked loose when i resealed the oil pan and eventually got at it.
beginning rebuild/restore on the truck inside a month, and the engine will no longer be naturally aspirated @ that point.
BTW, I get a solid 22mpg with it when i'm beating on it locally, up to 31mpg highway, and around 26 or 27mpg driving it "normally". the truck is 4x4 with 3" lift and 31x10.50's, d30 front, d44 rear (finally...I blew 4 dana 35's with this and just kept swapping because they were byproducts of other projects thus free) 3.55 gears. an ax5 WON'T survive behind a 3800...I'm on number 5 and the max. miles I've gotten on an ax5 now is 1200...again, just replace as I have had many parts xj's and whatnot with trans, and I can build a good one between two bad ones.
oh, it outputs around 227hp and 263ft/lb's torque, from the build sheet on the motor. better than a 4.0 even stock too. Get those numbers with a 4.3 and see what kind of mileage you get...bet it won't even come close.
beginning rebuild/restore on the truck inside a month, and the engine will no longer be naturally aspirated @ that point.
BTW, I get a solid 22mpg with it when i'm beating on it locally, up to 31mpg highway, and around 26 or 27mpg driving it "normally". the truck is 4x4 with 3" lift and 31x10.50's, d30 front, d44 rear (finally...I blew 4 dana 35's with this and just kept swapping because they were byproducts of other projects thus free) 3.55 gears. an ax5 WON'T survive behind a 3800...I'm on number 5 and the max. miles I've gotten on an ax5 now is 1200...again, just replace as I have had many parts xj's and whatnot with trans, and I can build a good one between two bad ones.
oh, it outputs around 227hp and 263ft/lb's torque, from the build sheet on the motor. better than a 4.0 even stock too. Get those numbers with a 4.3 and see what kind of mileage you get...bet it won't even come close.