Engine 84 CJ7 Engine Swap

[Bartman1959]

I'm looking at buying an 87 CJ7 with a blown engine. "Blown" as in a rod through the block, not an 871 blower. It had the AMC 258 i6 / 4.2l in it, but curious what other NON SBC Jeep options I have using the existing Transmission /Transfer Case . I would love to drop a AMC 304 in there, but not sure what that swap entails. Any guidance here would be greatly appreciated.

 

[Petescj]

I'm looking at buying an 87 CJ7 with a blown engine. "Blown" as in a rod through the block, not an 871 blower. It had the 4.2 in it, but curious what other NON SBC Jeep options I have using the existing trans/transfer case. I would love to drop a 304 in there, but not sure what that swap entails. Any guidance here would be greatly appreciated.

Id pass over the AMC 304 and go straight to a 360. Not a difficult swap really. Different motor mounts , upgrade the radiator, new exhaust. Cant get to detailed as Im starting work but what Transmission do you have? That could be your biggest issue

 

[caveman]

If you're going to swap for anything bigger than the AMC 258 i6 / 4.2l you might want to keep in mind that the whole drive train is weak also. You'll be swapping Transmission and axles before long.

 

[TSB8C]

I had the AMC 258 i6 / 4.2l also, mated to a T-150 . Ran, but weak and tired. I installed a Crate "ZZ6 EFI" and love it. Wanted fuel injection and a V8 and this was a great choice. Brand new, under warranty, 420HP, and based on the proven SBC with lots of after-market support. Homemade motor mounts and dual exhaust, which you'll need anyway, along with a new rad you'll also need anyway. Mated that to a 700R4 (I wanted auto and Overdrive ) and then a Novak adaptor for the Dana 300 Transfer Case . Some 1-piece axles and different gearing in the AMC20 rear end and it's a solid performer. Highly recommended engine and an easy swap. SBC's are everywhere, supportable, and adaptors exist for many tranny options.

 

[Bartman1959]

I had the 4.2 also, mated to a T150. Ran, but weak and tired. I installed a Crate "ZZ6 EFI" and love it. Wanted fuel injection and a V8 and this was a great choice. Brand new, under warranty, 420HP, and based on the proven SBC with lots of after-market support. Homemade motor mounts and dual exhaust, which you'll need anyway, along with a new rad you'll also need anyway. Mated that to a 700R4 (I wanted auto and overdrive) and then a Novak adaptor for the D300 transfer case. Some 1-piece axles and different gearing in the AMC20 rear end and it's a solid performer. Highly recommended engine and an easy swap. SBC's are everywhere, supportable, and adaptors exist for many tranny options.

The problem with the SBC swap is that I want to keep a Jeep a Jeep. If I wanted a Chevy, I'd buy a Chevy. Sorry, but I can't think of a single reason to have 420 hp in a CJ7 . I'm glad you're happy with your build, but it's not for me.

 

[Bartman1959]

If you're going to swap for anything bigger than the 4.2 you might want to keep in mind that the whole drive train is weak also. You'll be swapping transmission and axles before long.

I'm not really concerned with a weak drive train as I won't be wheeling it, or racing it. I just want a reliable 4X4 for in the snow. I won't be wheeling in DEEP snow either.

 

[Petescj]

The problem with the SBC swap is that I want to keep a Jeep a Jeep. If I wanted a Chevy, I'd buy a Chevy. Sorry, but I can't think of a single reason to have 420 hp in a CJ7. I'm glad you're happy with your build, but it's not for me.

The 360 is fine in a CJ7 . Do you know what Transmission you have? A T-176 will hold up behind the V8 and bolt right up no adapters needed. Any other 80s transmission isnt really worth it even for street driving unless you have the auto TF999 . All the other manuals of that era ( T-4 ,T-5 , SR4 ) notoriously weak even behind the AMC 258 i6 / 4.2l

 

[Bartman1959]

The 360 is fine in a Cj7. Do you know what transmission you have? A T176 will hold up behind the V8 and bolt right up no adapters needed. Any other 80s transmission isnt really worth it even for street driving unless you have the auto TF999. All the other manuals of that era ( T4,T5, Sr4 ) notoriously weak even behind the 258

I just received a message from the current owner, and he says he thinks it's a 5 spd, but doesn't know which one. He hasn't driven the Jeep in over 4 years.

 

[Petescj]

I just received a message from the current owner, and he says he thinks it's a 5 spd, but doesn't know which one. He hasn't driven the Jeep in over 4 years.

If it originally came with the Jeep and its a 5 speed its the T-5 . Only one ever offered in a Cj. While its nice to have the Overdrive its just not very durable. If you read up on it some dont confuse it with a word class T5 , thats a totally different animal. By design the shifter is hung way at the back of the Transmission which causes issues right off the bat.

 

[Petescj]

Heres some good info on Cj transmissions.

https://jeep-cj.com/community/threads/manual-cj-transmissions.43554/


For what your using your Cj for Id recommend a T-176 . Prices vary pretty much on these lately. Anywhere from $400 to $900 Ive seen.

 

[TSB8C]

The problem with the SBC swap is that I want to keep a Jeep a Jeep. If I wanted a Chevy, I'd buy a Chevy. Sorry, but I can't think of a single reason to have 420 hp in a CJ7. I'm glad you're happy with your build, but it's not for me.

I hear what you're saying and wouldn't dispute any of it. I do use mine as a daily driver in Houston traffic (in addition to camping and hunting trips) and enjoy that "butt in the seat" feeling HP gives you. I also gave up my custom built Harley chopper and am probably using the Jeep as a bit of a mental replacement for my mid-life crisis years. As for the SBC, I have always driven Chevys, even before getting my first jeep about 30 years ago. So it's an engine I love, am comfortable and knowledgeable wrenching on, etc. When going EFI, I did that on two prior AMC 304 's with poor results (bolt-on kits from AFI and one from Holley). Getting an already built fuel injected engine with the computer and tuning already done as a kit and under warranty was also easy with a Crate SBC. One thing I love on this forum is the various ideas, different perspectives and viewpoints, and a chance to hear from others on their varying failures/results.

 

[Project86]

SBC parts are easy to get. AMC 304 /360 not so much.

 

[WHATROAD]

If I read correctly, the type of driving you are looking to do , a reman AMC 258 i6 / 4.2l 258 is the perfect engine. no need to change any other components to make it work as planned. I'm very happy with mine. gas milage isn't bad either

 

[WHATROAD]

I'm also presuming that the 87 is a typo and you meant 84. The 87 would be a Mopar yj and a different beast. Rectangular headlights the least of them

 

[Bent]

1986 was the last year for the CJ7 . Is this a YJ?

 

[CJ]

1986 was the last year for the cj7. Is this a YJ?

Could be but aloo could be a typo. We will see...

 

[Patrick]

“I installed a Crate "ZZ6 EFI" and love it. Wanted fuel injection and a V8 and this was a great choice. Brand new, under warranty, 420HP, and based on the proven SBC with lots of after-market support.”

TSB8C, what factor steered you away from all the different LS engines…

 

[TSB8C]

"TSB8C, what factor steered you away from all the different LS engines…"

I have always driven Chevy's and have many years (over 35 years) building a comfort level with the SBC. So personal experience and familiarity was the biggest factor. I used homemade motor mounts and exhaust rather than buy some kit since I've also done that in other vehicles. I also wanted the 700R4 "computerless" tranny (prior experience again) rather than a computer driven 4L60e or 4L80e since the Edelbrock ECU setup on the ZZ6 was minimal and easy. The Edelbrock ECU is also programmable from a phone or tablet via a bluetooth link where the LS engine systems are more complicated. My son and I installed an LS3 with a 4L60e ("Connect and Cruise" package) into a '58 Apache pickup and had a number of issues with tuning and reliability (the tranny crapped out at about 10K miles and some other problems). And of course after market support for the SBC can't be matched. So the price point was right, it was easy, no tuning issues, and so far has been working great. The only challenge was been heat buildup. Around town and in traffic, no problem. The Contour dual fan and 4-core aluminum radiator work great. But hit the freeway and do 70 for 30 mins or more and the temp started to rise. Cut vent holes in the sides of the hood and that helped, but not fully resolved. Added the hood scoop (actually cut the hood so it's functional) and added an air breather spacer to lift the air cleaner up into the scoop. No more heat problems.

 

[iamjwh]

I relpaced the original AMC 304 engine in my 1978 CJ7 with a long block from Titan engines in Florida and had it shipped to New Mexico a couple of years ago. Engine, T-150 , Dana 30 , and original axles have all worked fine for the last 3 years. Very happy. Titan did a great job and I'm sure I spent less than having one of the locals do it.

The only problem I had was figuring out I needed an electric pump. I'm at 7550 elevation and restricted to ethanol gas...which has a lower boiling point... and since the fuel lines run really close to the exhaust, vapor lock was a constant problem.

It doesn't get very good mileage, 12-14 mpg, but from the reviews I've read efi isn't worth it.

Used as a daily driver, it'll go 70 on the highway no problem. Pulls up to 3500 lbs. or so. I did remove all the pollution they installed on it back during the Carter administration when mandates for the 304 reduced the hp from 200+ to about a hundred.

The 360 is a great engine, but there's nothing wrong with the 304 for my needs. Love it. If you go to the 360 I believe you'll have to change the flywheel... but otherwise it should be an easy install.

I did buy another 304 and a t150 and plan to install them on my 59 Willys wagon this summer. If anyone has suggestions on axles etc. please let me know.

 

[Patrick]

"TSB8C, what factor steered you away from all the different LS engines…"

I have always driven Chevy's and have many years (over 35 years) building a comfort level with the SBC. So personal experience and familiarity was the biggest factor. I used homemade motor mounts and exhaust rather than buy some kit since I've also done that in other vehicles. I also wanted the 700R4 "computerless" tranny (prior experience again) rather than a computer driven 4L60e or 4L80e since the Edelbrock ECU setup on the ZZ6 was minimal and easy. The Edelbrock ECU is also programmable from a phone or tablet via a bluetooth link where the LS engine systems are more complicated. My son and I installed an LS3 with a 4L60e ("Connect and Cruise" package) into a '58 Apache pickup and had a number of issues with tuning and reliability (the tranny crapped out at about 10K miles and some other problems). And of course after market support for the SBC can't be matched. So the price point was right, it was easy, no tuning issues, and so far has been working great. The only challenge was been heat buildup. Around town and in traffic, no problem. The Contour dual fan and 4-core aluminum radiator work great. But hit the freeway and do 70 for 30 mins or more and the temp started to rise. Cut vent holes in the sides of the hood and that helped, but not fully resolved. Added the hood scoop (actually cut the hood so it's functional) and added an air breather spacer to lift the air cleaner up into the scoop. No more heat problems.

Got some relevant questions for you but don’t want to sidetrack the thread. I’ll PM you.