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Unread 05-31-2014, 03:11 PM   #1
TexasMan
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1984 CJ7 
 
Join Date: Mar 2014
Location: Austin, TX
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1984 CJ7 Needs a Replacement Engine

Hello Yall,
I just bought a 1984 CJ7 with a cracked engine block (Cylinder #4 is cracked and antifreeze is dripping through the cylinder wall). You can follow the details of how I arrived to this thread by viewing my original thread (1984 CJ7 not Running). I need your help in figuring out what my options are for getting this jeep running again ((I nicknamed the jeep "Bobcat", or "Bob" for short).

Bob is not my daily driver, I bought him as a vacation vehicle to pull behind the RV and to go off-roading on the weekends. The maximum towing capacity of my RV is 3500 pounds, so I need to make sure that whatever engine option I use keeps the jeeps weight under 3500 pounds

Here are some facts about Bob:
1- It has a 4 cylinder 150 CID engine with only 77K
2- Engine was bored and currently has pistons that are .060 oversized
3- Standard 4-gear transmission
4- No AC and no power steering
5- 31x10.5xR15LT BFGOODRICH Baja Champion tires
6- I have a 360 Engine from a 1972 truck setting in my garage
7- Bob and I live in the Austin area (Lago Vista, about 30 miles NW of Austin)
8- Limited money...I am a working man!!

Questions:
1- What year model engines would fit into my 84 CJ?
2- is it a big pain to have things fit if I upgrade to a used six cylinder?
3- I know a six cylinder will be a better engine down the line, but am I better off trying to find a 4 cylinder engine block and rebuild the one I have considering what I will be using the jeep for?
4- Is their a specific source for buying used jeep engines, or is Craig's List still king?
5- I am open for all suggestions and Tips

Note:
For those of you who are curious why I bought a jeep with a cracked engine block, the answer is: I did not know it had a cracked engine block, neither did the former owner...I knew him before I bought the jeep from him

Thank you all in advance for your thoughts and suggestions

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84 CJ7 (2.46L)
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"I nicknamed My jeep "Bobcat", and it bit me in the rear"
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Unread 05-31-2014, 04:27 PM   #2
JustDandee
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1983 CJ7 
 
Join Date: Apr 2013
Location: Nampa, Idaho
Posts: 104
I might be in the same boat, same drive train- tearing into the engine again after changing the head gasket and still pressurizing the cooling system. I think the general thought is if you upgrade the motor then you will need to address the rest of the drive line to handle the power specifically the tranny And to do the conversion you have incidentals to address like a larger rad to cool, dual exhaust to install which cost money. I will let people with more first hand knowledge clarify since you already have a donor engine.

Dan
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Unread 05-31-2014, 05:00 PM   #3
RenoF250
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Location: Foresthill, CA
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Quote:
Originally Posted by TexasMan View Post
Hello Yall,
I just bought a 1984 CJ7 with a cracked engine block (Cylinder #4 is cracked and antifreeze is dripping through the cylinder wall). You can follow the details of how I arrived to this thread by viewing my original thread (1984 CJ7 not Running). I need your help in figuring out what my options are for getting this jeep running again ((I nicknamed the jeep "Bobcat", or "Bob" for short).

Bob is not my daily driver, I bought him as a vacation vehicle to pull behind the RV and to go off-roading on the weekends. The maximum towing capacity of my RV is 3500 pounds, so I need to make sure that whatever engine option I use keeps the jeeps weight under 3500 pounds

Here are some facts about Bob:
1- It has a 4 cylinder 150 CID engine with only 77K
2- Engine was bored and currently has pistons that are .060 oversized
3- Standard 4-gear transmission
4- No AC and no power steering
5- I have a 360 Engine from a 1972 truck setting in my garage
6- Bob and I live in the Austin area (Lago Vista, about 30 miles NW of Austin)
7- Limited money...I am a working man!!

Questions:
1- is it a big pain to have things fit if I upgrade to a used six cylinder?
2- I know a six cylinder will be a better engine down the line, but am I better off trying to find a 4 cylinder engine block and rebuild the one I have considering what I will be using the jeep for?
3- Is their a specific source for buying used jeep engines, or is Craig's List still king?
4- I am open for all suggestions and Tips

Note:
For those of you who are curious why I bought a jeep with a cracked engine block, the answer is: I did not know it had a cracked engine block, neither did the former owner...I knew him before I bought the jeep from him

Thank you all in advance for your thoughts and suggestions
A six will fix just fine. If it is a 4 speed it is probably a T4 which is okay behind a 6.

How would you rebuild this engine if it is cracked and already been bored?

Craigslist is what I use. If you want to go to an EFI 4.0 you could look at Cherokees. They are often pretty cheap, I got one for free but I had to rebuild the engine.
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Unread 05-31-2014, 05:13 PM   #4
gazzo
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I bought my cj7 in 96 just like yours. Loaded up with four people and a decent hill it was a dog. The plan was a 5.0 injected V8 and 4sp auto. $4500 just for that combo on a pallet back in the day so opted for a stock I6 to get me through. I still run that 258 now. Was pretty green and didn't know about the costs and what I was getting in to. Australia was not a good cheap place to source AMC engine parts. Any hoo ironically $4500 later I had my reconditioned by me 258 with +.060 pistons, new bearings throughout, ground crank etc etc setting in front of the stock T5. It has been fine ever since. You will need a different bell housing and clutch assembly and radiator to get the porting right for the 6, and engine mounts. That is all. It's a fun swap to do and you won't regret it. You will do it there in USA for next to nothing. My guess is you'll have low 4.10 diff gears too like I do so wheeling wherever your RV takes you will be easy peasy. Good luck
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Unread 05-31-2014, 05:26 PM   #5
TexasMan
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Thanks for your replies. RenoF250, the answer to your question is that I thought if I could get a 150CID engine black and get it bored out to .060, then I should be able to transfer everything else from my current engine.
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Unread 05-31-2014, 05:36 PM   #6
cookingguy
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Do the 360 I am doing one in my 5 right now not to much work at all
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Unread 05-31-2014, 08:58 PM   #7
RenoF250
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Quote:
Originally Posted by TexasMan View Post
Thanks for your replies. RenoF250, the answer to your question is that I thought if I could get a 150CID engine black and get it bored out to .060, then I should be able to transfer everything else from my current engine.
Ah, I see. I have not heard anyone happy with the 4 cylinder that drives it on the road. They can be okay off road depending on what kind of driving you do.
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Unread 05-31-2014, 09:20 PM   #8
TexasMan
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"Cookingguy", please keep me posted on how it goes with the 360 conversion. I imagine a bunch of things will have to be replaced to handle the extra power of the 360 engine as far as axles and suspensions are concerned!
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Unread 05-31-2014, 10:31 PM   #9
wellmax
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I have a 1984 model with the 150 engine and 4 speed
I went with a new short block from NAPA, it worked out ok.

better check out all motor transmission combinations, as 1984 was a big change year for Jeep. AMC

before 1984 they used the GM Iron Duke 4 banger, then in 1984 changed to the AMC 150,

per an old mechanic the AMC 150 was not near as tough an engine as the Iron Duke.

All I know was that my little AMC 150, at 135K miles was so worn out that the pistons swapped cylinders sometimes. Had to run 50 weight oil in it near the end, but it was still running when I drove it to the shop for engine replacement.

Is the little AMC 150 a power house, no, but it will do 55 mph and believe me unless your total front end has been rebuilt, that is about all the speed you will feel save with.

These old jeeps were not designed to be racers. just tough old field and trail vehicles that could be driven on the road at moderate speeds.

now the new jeeps, high speed and you can run with the big dogs.

Just my two cents!!!!!!
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Unread 06-01-2014, 05:48 AM   #10
gosupes
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You want to do it on the cheap? Then rebuild the 150. Have a long block built and move the accessories over. Need something with a little more get up and go without too much work? Get a 258. You can use the same trans with some minor mods. Just remember that anything other than the 150 will require new exhaust, attention to cooling needs, drivelines lengthened/shortened among other minor issues. If you go with a V8, expect to start having to upgrade other parts of the drivetrain to compensate for the extra power.
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1986 CJ7, 4.2 w/4.0 head, TFI-HEI hybrid ignition, Clifford manifold w/Holley 390 w/cold air intake, OBA, 4.5" lift, Woody CV shaft and Tattons in front, 4.10 gears - lunchbox in front, Truetrac in the back, twin-sticked, blower upgrade for running topless, trying to keep it simple.

It's just a Jeep, and if you don't wheel it once in a while, it's not even that.
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Unread 06-01-2014, 06:05 AM   #11
Mike Romain
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Quote:
Originally Posted by TexasMan View Post
Thanks for your replies. RenoF250, the answer to your question is that I thought if I could get a 150CID engine black and get it bored out to .060, then I should be able to transfer everything else from my current engine.
I would worry about that. I think the .060 overbore might have contributed to that crack, although chunks of metal bouncing around can hit hard or cause the piston to slap.
Others likely know more about what the safe or Max bore limit is.
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86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
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Unread 06-01-2014, 06:13 AM   #12
Matt1981CJ7
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This is a no-brainer. Drop the 360 in and have some fun.

It's an easy swap, and won't add too much power or weight.

Matt
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Unread 06-01-2014, 08:16 AM   #13
Mike Romain
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The chart I found says the 84, 2.5 has a curb weight of 2750 lb so you have lots of wiggle room that way. ( Google searched 'weight of 84 CJ7' and found a site with all the specs)

Personally I would go for the V8 for a part time use like you intend. I wanted gas mileage for my 86 daily driver so went with another 6.
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86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
Some Canadian Bush Jeep Runs and Build Photos: http://mikeromainjeeptrips.shutterfly.com (10 new albums added Sept 16/10)
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Unread 06-01-2014, 09:12 AM   #14
TexasMan
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Thanks so much for all the tips. Dropping the 360 in would be the logical choice since I already have it. However; I received the following tip from another member regarding a 360 swap, which is a concern:

If you put in the 360 you would need to upgrade the transmission and replace or modify the axles. You have a Sr-4 tranny which is a car transmission your rear is an AMC 20 with 2 piece axles. You would need to replace the axles and put a truss on the axle.

Per his comments, this will be an expensive upgrade if I have to do everything he is saying! What do yall think?

Question:
How do I confirm the following:
1- The transmission model (I know it is a 4 speed manual)?
2- Transfer case model, was the Dana 300 the only option for the 84 CJ7)?
3- Front and rear Axle sizes?
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Unread 06-01-2014, 09:22 AM   #15
Mike Romain
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The stress depends on your driving habits. If you plan on seeing what the 360 can do with oversized tires (33" +)on it and have a heavy foot, or plan on racing/hill climb/high torque situations then you could have issues.

If you just want something to buzz around on the trails with using moderate (31" +/-) tires that has good highway manners, then you shouldn't have too many issues in my mind.
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86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
Some Canadian Bush Jeep Runs and Build Photos: http://mikeromainjeeptrips.shutterfly.com (10 new albums added Sept 16/10)
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