273 engine swap into a Jeep CJ5

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Jeff Oppenheimer

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Greetings everyone... I am a brand new member and have a question about an engine swap of a 273 into a 1980 Jeep CJ5... has anyone ever done this? If so will the current transmission bolt up to the engine or will I need a different bellhousing? Any information would be great! Currently the jeep has the inline 4-cylinder. I am assuming I would need new engine mounts but just curious if this is worth the trouble... Thanks again!
 
The 318 (5.2 liters) was brought out in 1967; the main difference from the 273 was its larger 3.91” bore. The 318 was never used as a performance engine by Chrysler; the 273 four-barrel matched it in peak horsepower, and the more performance-oriented 340 was quickly released in 1968.

With the above info in mind, I would contact these guys: Dodge Small Block V8 Universal MMX Series Engine Mounts for Jeeps and Other Vehicles


Oh, and :welcome:
 
Probably going to need to change the transmission, clutch and bell housing, or automatic trans to a 904 or 727 to match up to the V8 blocks. Then you will have to look at the drive shaft length too.

Just as easy to put a 318 in it as they are a lot more plentiful, and lots of rebuild parts available for them too. Mild cam and a 4 barrel carb wakes them right up.
 
Welcome!
Back in the 70s a friend put a 318 in an old military surplus jeep to use as his ranch buggy. He got an adapter bellhousing from JC Whitney. We fabricated everything else. I would assume someone still makes adapters for your combo as older Jeep/v8 swaps are one of the most common swaps there is.
 
I put a small block mopar in a CJ-7 years ago, nothing bolts up, used a NP435 from a Dodge truck and 203 transfer case, the rear driveshaft was so short, that it would fit in a shoe-box.
The CJ-7 has 12" more wheelbase than a CJ-5.

What 4cyl is currently in your jeep, the old iron duke? If so a Chevy engine will bolt to the bellhousing.
 
Cant help with your answer but two brothers I knew put a built 318/904 in a right hand drive mail Jeep with a 150 shot. It was a white knuckle ride for sure.
 
i helped a friend put a 318 in an old CJ7 years ago. you'll beed a mopar trans. we used the stock trans that was in the jeep (904 with amc bell housing) and put the inside into a mopar case. worked awesome.
 
Guys, his jeep is a CJ-5, no room for an auto in a CJ-5.
 
i had a 72 cj5 that had a turbo 400 in trhe thing when i got it. i put the manual 3 speed back in it.
 
abodyjoe said:
i had a 72 cj5 that had a turbo 400 in trhe thing when i got it. i put the manual 3 speed back in it.
Click to expand...
The factory never put an auto in a CJ-5.
I would have liked to see how that turbo 400 was wedged in there.
Yes I like my Jeeps, still have several.

1980 CJ-5 258 4-speed wife's toy.
PWlQcV.jpg


My 1948 CJ-2A 134 flathead 3-speed.
fvOPNU.jpg
 
What transmission is in there now, T-176 4-speed? The easiest path forward if you must put a 273 in it would be to use an AX-15 5-speed out of a 318 Dakota which will almost bolt to the Dana 300 transfer case, or a NP435 out of a Dodge truck, and an adapter to mate it to the Dana 300. Novak Conversions Home would be a good place to research adapters. Does the Jeep have a 258 in it now? (edit, you have the 4 cylinder which has a Chevy bolt pattern) If so, a later 4.0L swap would be a lot easier, and if you put the 258 crank into the 4.0 you end up with a 4.6 which is about the same displacement and will produce far more low rpm torque than a 273.
 
sireland67 said:
The factory never put an auto in a CJ-5.
I would have liked to see how that turbo 400 was wedged in there.
Yes I like my Jeeps, still have several.

1980 CJ-5 258 4-speed wife's toy.
PWlQcV.jpg


My 1948 CJ-2A 134 flathead 3-speed.
View attachment 1715576342
Click to expand...


obviously the factory didn't do it.. it also had a amc 360 in it.. freaking thing was fast.
 
lilfontleroy said:
The 318 (5.2 liters) was brought out in 1967; the main difference from the 273 was its larger 3.91” bore. The 318 was never used as a performance engine by Chrysler; the 273 four-barrel matched it in peak horsepower, and the more performance-oriented 340 was quickly released in 1968.

With the above info in mind, I would contact these guys: Dodge Small Block V8 Universal MMX Series Engine Mounts for Jeeps and Other Vehicles

Thank you! Would the current 4 sp tranny hook up to a 273 or 318?


Oh, and :welcome:
Click to expand...
 
abodyjoe said:
obviously the factory didn't do it.. it also had a amc 360 in it.. freaking thing was fast.
Click to expand...
Somebody must have pulled the drivetrain out of an old wagoneer or pickup.
Yes a factory 360 makes a CJ jump.
I have one crazy buddy that has a 74? CJ-5 he bought new, he put a built 401 in it.
That 401 opens up like a dirt track stock car, it revs fast and has tremendous torque.
When we go wheeling for a weekend, he brings a spare 3-speed and trans with him, he says they are easy to change, and every chain has a weak link.
 
Damn that sounds fun... I'm looking for more of a street-legal option that can give me more horsepower than this itty-bitty 4 cylinder... Does anybody know if I need to change out the transmission I put this to 73 in it? Maybe get a different bellhousing? There's a guy selling a 273 that is totally complete and only wants five hundred bucks for it... I don't need that much horsepower but more than a 4 banger... Thanks for the options!
 
Put the Weber Progressive 2 barrel carb kit on your Jeep 2.5 carberated 4 cyl. That will give it some more fuel and wake it up.

Easy to do with these kits, lots lots easier than doing a V8 Swap Over.

Jeep 2.5, 4 cyl with the One Barrel Carb:

s-l400.jpg


Progressive 2 Barrel Carb Kit for Jeep 2.5,
4 cyl.

Screenshot_20200811-204531_Gallery.jpg


Screenshot_20200811-204631_Gallery.jpg
Screenshot_20200811-204349_Chrome.jpg


Have used these Progressive Carbs many times with great success.


Running one on my performance built Dune Buggy, VW 1835cc 4 cyl Air Cooled engine with Progressive Carb. Always opening up the Secondary as a normal part of driving it.

Pulls Good, Runs Good . . .

Buggy Snow Plow.jpg


Plow snow with it in the Winter time too.
 
What transmission is in it now? If it's a T-176, it MIGHT survive behind a stock 2 Bbl 273 if driven gently. If it had the SR-4, which was common behind the "Iron Duke" 4 cylinder, replace it with something stronger, it will fail.
 
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I have the "what was once" the answer.........sorta........

Back in the day you could buy (Advance Adaptors?) an adapter that mated a Chrysler A833 4 speed to a Jeep transfer case. I still have what's left of it........used in a Toyota LC with a SB Mopar and Jeep "straight through" transfer case

The problem.......I knew 2 othter guys had these, and they all had same problem.........improper clearances for syncros.......mine eventually destroyed 3rd ? gear syncro, and the shaft was not hard enough.........the jeep transfer case main drive gear ate itself into the splines of the adapter shaft and eventually the thing would neither stay in high nor low range without "bungee cord" on the shifter

It was fun while it lasted.
 
Thanks everyone for the great advise! I am new to the Jeep CJ5 arena. The engine runs great right now ... it was an Arizona Jeep and virtually no rust on it so I'm going to lift the cab off and freshen up the paint and while it's off I'm going to clean all the frame and pretty up the engine... I'm kind of leaning towards the Dual carb... thanks again for all of your help... it needs a few things like tail light lenses and the pull knobs for the heating system are there but they come off when you pull them... Any suggestions on places to acquire Parts like this... also fuel gauge not active.

Thx again!
 
Jeff Oppenheimer said:
Thanks everyone for the great advise! I am new to the Jeep CJ5 arena. The engine runs great right now ... it was an Arizona Jeep and virtually no rust on it so I'm going to lift the cab off and freshen up the paint and while it's off I'm going to clean all the frame and pretty up the engine... I'm kind of leaning towards the Dual carb... thanks again for all of your help... it needs a few things like tail light lenses and the pull knobs for the heating system are there but they come off when you pull them... Any suggestions on places to acquire Parts like this... also fuel gauge not active.

Thx again!
Click to expand...
The good thing about a Jeep is virtually every part is available, there are tons of suppliers of jeep parts.
4wd Hardware is one, just do a google search.
 
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