86 Jeep cj 7 engine swap

[ron86cj7]

Really need some help on this one......I bought a 86 jeep cj7 with the 2.5 4 banger engine, T-4 trans and 373 rear. Jeep has 33" tires which takes away a lot of the power. The 4 cyl runs good, just not enough power. I found a 4.2 out of a 80 model cj7. Has anyone made this swap before? I am told that everything will bolr right up....may need to change motor mounts, radiator and bell housing...and that is it. I have limited funds to do this. I got the 4.2 complete engine for $200.00 and have an estimate of $650.00 to completely rebuild it, and then another $500.00 to install.

I am sure there is going other expense....I had thought about putting a 350 chev engine.....but think it would be more money.......ANY Advice and guidance..............Thanks in advance.

 

[superj]

google or search on the sites. i, personally, cannot help or give any advice, since i have never done this swap

 

[Saddle Tramp]

In my world it is nice to keep a Jeep, Jeep. I believe you lower the value of a CJ when you stuff a Chevy or Ford motor in them. Not to say I haven’t done it but I learned the error of my youthful ways.

The T4 is going to be your weak link as it is a light duty transmission that was never offered behind the 258 and most likely wouldn’t hold up. The Dana 300 transfer case you have is the best part of the drive train. Although it doesn’t have a deep granny low such as a wide ratio T18, the T176 may be your best option. The T176 was offered by Jeep in the CJ of your vintage and with luck you may be able to come up with the original AMC bell housing and transmission; this is really as close to a bolt in set up as you are going to get. The more OEM bone yard parts you can come up with the cheaper this swap is going to be. You will also be looking for new motor/transmission mounts, clutch, radiator, and electrical components to make the motor run. Your budget is going to be tight but keep looking (bone yards, Craigs List, ebay, and other jeepers) until you find what you need and remember, the search is half the fun!

 

[jps4jeep]

I have a couple of differeing opinions on what you have here.

regardless of a 4.2 swap or a carbed SBC swap, they will cost about the same depending on your ability to fabricate stuff like motor mounts.

the T4 is going to be a PITA, as far as I am concerned, it was not a great transmission even behind an underpowered 4 cyl. I would highly suggesta finding an AX15 at best, probably get a good used one for about $100, if you have the skills, a rebuild kit done at home on a bench shouldn't cost more than $100.

Going from a carbed motor to another carbed motor has never been ideal in my mind, yes it is easy and cheap, but you really don't gain a whole lot in reliability, tuned longevity, and economy. I highly recommend sourcing a EFI or TBI set up for the 4.2. I have seen Howell injection kits selling pretty cheap as of late, when first introduced they were well over $1000, now you can find them for about $400 and that is money very well spent.

Good luck and keep us posted.

 

[ron86cj7]

In my world it is nice to keep a Jeep, Jeep. I believe you lower the value of a CJ when you stuff a Chevy or Ford motor in them. Not to say I haven’t done it but I learned the error of my youthful ways.

The T4 is going to be your weak link as it is a light duty transmission that was never offered behind the 258 and most likely wouldn’t hold up. The Dana 300 transfer case you have is the best part of the drive train. Although it doesn’t have a deep granny low such as a wide ratio T18, the T176 may be your best option. The T176 was offered by Jeep in the CJ of your vintage and with luck you may be able to come up with the original AMC bell housing and transmission; this is really as close to a bolt in set up as you are going to get. The more OEM bone yard parts you can come up with the cheaper this swap is going to be. You will also be looking for new motor/transmission mounts, clutch, radiator, and electrical components to make the motor run. Your budget is going to be tight but keep looking (bone yards, Craigs List, ebay, and other jeepers) until you find what you need and remember, the search is half the fun!

Good Morning Saddle Tramp...Thanks for your input...your comments reminded me as to why I bought the CJ7 to begin with. Keeping the jeep as a "jeep" is important. The 86 was the last year of the cj classic, my thought was surely they have most if not all of the bugs out since1974. I read somewhere that jeep changed the bell housing in 1983 to accomidate another type of engine (chev??) not sure of what I was reading. My big concern now is that the engine I bought (80 model) will not work after spending the money to have it rebuilt. The T-4 that I have is good with no problems, however for the good of the project, should i get the transmission and engine as a "one piece deal" this would include the bell housing. Then what about the drive shaft...should I also try and pick that up too (all of this off of the 80 jeep renigade. Was there any major changes on the engine and transmission from the 80 to 86 that would make this swap not work? I am thinking this whole swap is going to run me about $2,000.00 when all is said and done. The 2.5 that I have is a good running motor with no problems. However, living in Raleigh NC the traffic is very heavy and my main point in all of this is to have the power to get out of the way when i need to and to have enough top end to keep up with interstate traffic. with that being said....am I on the right path in swaping out the 4 cyl to a 6 cyl or is there enough things that can be done to the 4 cyl to meet my objective and no break the bank? Thanks in advance.

 

[firemanharry]

Wasn't the 4 Cyl a GM motor (the Iron Duke) back then, or was that earlier? Either way there was so much GM and Ford parts in Jeeps back then I would say the "keeping it Jeep" line is a little fuzzy. If you're worried about keeping it stock then just regear....that little 4 banger was a damn good engine.

I also don't know about dropping the value of a Jeep by throwing a SBC in it, the value of mine went up when it rolled out of the shop with that unmistakable sound rolling out of the dual exhaust. To each his own but I agree with Johnny on EFI over Carbed, they're so much more efficient and serviceable and Howell does make a helluva good system.

If I were you and working on a limited budget with a good running GM 4 banger, I would step up to fuel injection and throw some lower gears in. I'm not sure what you should go to for gearing to get your set-up right but I'm sure someone here can help with that.

 

[firemanharry]

Okay, I just saw that the GM 4 2.5 was used from 80-83. In any case I would use the good running Jeep 2.5, look for a howell set-up and regear. You'll be surprised by the difference the fuel injection will make on it's own.

 

[Saddle Tramp]

It is true, Jeep begged, borrowed, and stole parts from anyone they could so I understand what Dave is saying. In fact, the 1980 CJ5 that I use to own had a very tiny bowtie in the middle of the OEM steering wheel; GM’s way of rubbing it in a little I guess. My point is if you use parts that were available on a Jeep from the factory you have maintained the integrity of the ride. I know the SBC guys have their own opinion on this and that’s fine, what ever floats your boat, but if you have a decent CJ survivor why hack it up

To answer your question about the different bell housings, the 2.5, I4 used in the CJ from 1980 to 1983 was a GM motor and was nicknamed the “Iron Duke”. In 1984 Jeep started to use an AMC I4 dropping the GM bell housing bolt pattern.

Johnny’s point is also valid about going EFI now as it has many benefits however the Motorcraft 2100 or 2150 carb is a common swap out on the 258; it is cheap, reliable, and will work well when off camber. To get the EFI swap made now my bet is it will cost you more money before you are done which may cause you some budget hart ache.

It sounds like the donor vehicle is still available. If so, grab everything you can that you might need including the ignition module etc to make the engine run. (Also try to cut the connectors from the donor wiring harness to splice to your existing harness as they may be different.) Your life will be a lot easier, and it should be cheaper, if you can glean it all from the donor now than trying to find it later. As far as the drive lines it depends. If the donor has a lift (or no lift) that is comparable to yours then get them too; it could be a straight bolt in for you as opposed to having to have your drivelines reworked or buying new. Remember anything you buy now that you don’t need can go Craig’s List later.

 

[superj]

no doubt on that. the fuel injection does make a huge difference.

edit:

i agree on the carb with a 258. i have the 87 wrangler with 258 and i love it. i think that if you have a donor, you might as well get everything and use that since its available

 

[ron86cj7]

Thanks to everyone for your assistance. I have a lot to think about....Will be in touch as I make various decisions...I'm sure I will need more help.

 

[jps4jeep]

I do agree, a MC 2100 is a good carb to run on a 4.2, I was not saying that it was a bad way to go, I am saying that ideally if your going to go through the hassel of pulling a carb motor and swapping to somethingelse that has more power, it would be logical in my mind to also upgrade to EFI.

I've installed a number of these howell kits, mopar efi kits and the holley tbi pro-jection kit.

the mopar is the most expensive and probably the hardest to install.

the projection is pricey as well but is as simple as upgrading to a tbi and a + and - electrical conection.

Howell kit is cheapest, same electrical conection but you need to plumb a return line to the tank, which is realistically not hard.

the way I look at it is, other than initial price point to buy in. a howell kit will not require initial tuning, will not need to be adjusted during it's life span, will run at pretty much any level and altitude with out sputter and choking.

Carbs need initial tuning, regular tuning depending on climate, altitude, and will not run (or run well) at extreme angles.

I see the 20 minutes to run a return line to the tank and welding an o2 sensor in a lot quicker and easier than the time required to perform the above carb tuning.

 

[superj]

that looks so nice and easy to install. now i want fuel injection

 

[jakec]

i want fuel injection too nice kit.

 

[jps4jeep]

well I was on Howells site and they still price the kit at a grand, but I know you can find it else where cheaper.

 

[ron86cj7]

It is true, Jeep begged, borrowed, and stole parts from anyone they could so I understand what Dave is saying. In fact, the 1980 CJ5 that I use to own had a very tiny bowtie in the middle of the OEM steering wheel; GM’s way of rubbing it in a little I guess. My point is if you use parts that were available on a Jeep from the factory you have maintained the integrity of the ride. I know the SBC guys have their own opinion on this and that’s fine, what ever floats your boat, but if you have a decent CJ survivor why hack it up

To answer your question about the different bell housings, the 2.5, I4 used in the CJ from 1980 to 1983 was a GM motor and was nicknamed the “Iron Duke”. In 1984 Jeep started to use an AMC I4 dropping the GM bell housing bolt pattern.

Johnny’s point is also valid about going EFI now as it has many benefits however the Motorcraft 2100 or 2150 carb is a common swap out on the 258; it is cheap, reliable, and will work well when off camber. To get the EFI swap made now my bet is it will cost you more money before you are done which may cause you some budget hart ache.

It sounds like the donor vehicle is still available. If so, grab everything you can that you might need including the ignition module etc to make the engine run. (Also try to cut the connectors from the donor wiring harness to splice to your existing harness as they may be different.) Your life will be a lot easier, and it should be cheaper, if you can glean it all from the donor now than trying to find it later. As far as the drive lines it depends. If the donor has a lift (or no lift) that is comparable to yours then get them too; it could be a straight bolt in for you as opposed to having to have your drivelines reworked or buying new. Remember anything you buy now that you don’t need can go Craig’s List later.

Good Morning Saddle Tramp.......Still have not made a decision on the engine swap. My 4 banger runs great...thinking about things I can do to the engine to help with hp. It appears that the engine i have now is not the orgonial engine....is there any way i can tell if i have the GM motor
or the AMC engine? Thanks in advance.

 

[superj]

can't you pull the block number and find out?

 

[Saddle Tramp]

Good Morning Saddle Tramp.......Still have not made a decision on the engine swap. My 4 banger runs great...thinking about things I can do to the engine to help with hp. It appears that the engine i have now is not the orgonial engine....is there any way i can tell if i have the GM motor
or the AMC engine? Thanks in advance.

It is easy to tell the difference between the AMC I4 from the GM I4 used in CJs. On the AMC version the intake manifold and the exhaust manifold will be on the same side of the motor (driver) while the GM version will have them on opposite sides of the motor from each other.

 

[Bounty__Hunter]

Since you're limited on funds and the 4banger runs great, I'd regear the axles and get the engine back up higher in the RPM range where it's happier and most effective.

I think you'll get the most bang for the buck by regearing your axles to 4.88.

I run 5.38 gears behind my 4banger and push 35" tires easily, either on the trail or down the interstate at 80mph.

 

[ron86cj7]

I'm stll debating the engine swap, the regear, or the EFI. I was wondering though what everyone's tire size, engine, gear ratio, and then everyone's top speed with that ratio to try and gauge how much speed I would loose/gain.

Thanks!

 

[carnuck]

I would LOVE to find an '86 CJ7 I could afford here (I have a 360/T18A/NP208 I could put in) To put the 4.2L in, you would need the frame brackets and rad as well as bellhousing (T4 WAS used along with T5 with the 4.2L) I have a T5 bell in my pile of parts that also fits T4.