FJ40 LS Swap?

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FloridaLife

FloridaLife

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Because of all my low back surgeries and surgeries on both hips 41 years ago (and The Mayo Clinic says both hips need to be replaced), my wife is pushing me to do an automatic transmission swap. I have not been able to find an adapter plate to run an automatic transmission with my 2F, so I would have to do a V8 swap.

I would like to hear from those of you that have done V8 swaps. Have any of you done an LS swap? If so, I would like to hear any info, tips, and suggestions.

Were you able to use the OEM LS wire harness, or did you have to order one? If you had to order one, where did you get it?

What adapter did you have to use to connect to the transfer case?

Were you able to use your original driveshafts from your 4 speed?

Thank you for any info you can give. 👍
 
Use google to search Mud. mud search is not great. Quock search popped this link

gpfj40

Thread 'Advice Needed: LS V8 & 4L60e & 4 sp Tcase swap into 40 series'

I’m looking for some advice on engine placement from those who have done this swap before. After mocking the drive train in place I’m having trouble finding the best compromise that will lead to overcoming driveline angles and front drive shaft/trans pan clearance issues. These pics are how I’m thinking of proceeding. The front of the engine is shifted 1” to DS, the t case is shifted 1” to the PS. This is helping minimize front drive shaft interference as I hope to use a 1 piece front shaft. The motor and Tcase are as high and as far back as I can place them and they are sitting about...
 
ceylonfj40nut said:
Use google to search Mud. mud search is not great. Quock search popped this link

gpfj40

Thread 'Advice Needed: LS V8 & 4L60e & 4 sp Tcase swap into 40 series'

I’m looking for some advice on engine placement from those who have done this swap before. After mocking the drive train in place I’m having trouble finding the best compromise that will lead to overcoming driveline angles and front drive shaft/trans pan clearance issues. These pics are how I’m thinking of proceeding. The front of the engine is shifted 1” to DS, the t case is shifted 1” to the PS. This is helping minimize front drive shaft interference as I hope to use a 1 piece front shaft. The motor and Tcase are as high and as far back as I can place them and they are sitting about...
Click to expand...

Thank you!
 
FWIW, there are a number of companies that offer LS conversion wiring harnesses, and of course at different price points. In my opinion, Howell Engine Developments make an excellent harness and their customer service was top notch.

Conversely, I've also used an LS swap harness from BP Automotive. It was lower in price and in my opinion the money "saved" was nowhere near the extra work required. If there is another swap in my future... I will use a Howell harness.

Good luck with your LS conversion!
 
LS swap is fairly straightforward, I did a custom build 6.0 LS in my 40 after running a Vortec 5.7 for 23 years. And it really depends on your fab skills. It IS a lot of work, to do it right as you are more or less replacing the whole drivetrain but it is very doable

You’ll need custom motor mounts and you might as well toss the Toyota trans, IMO, it’s not going to hold up long and there are vastly better options to row gears with.

If you need to go automatic trans for your back a 4L80E is a good option. Advance Adapters will have what you need to adapt it to the transfer case.

You can retain the factory T-case using an adapter from AA.

Go to LT1swap.com You can re-pin a factory harness from a junkyard very cheaply, no need to spend big money on one. PCM programming is $75

This is not an LS but you’d be doing virtually the same thing. An LS is just a SBC with electronics. I’ll probably be setting the drivetrain in next week.

Rock40

Build Thread 'Ed’s Un-Did FJ40'

Un-done, Un-did, who knows 😂 Helping a friends Dad with a ‘71 FJ40 that’s been in pieces 20+ years. So it’s definitely been undone and some of the “Did” by the PO needs to get done again if you know what I mean. Not the first 40 I’ve worked on in pieces, probably not the last either.

Build: Chevy 400 SB (built 20 years ago so hopefully that’s good), NV4500, stock ‘71 transfer, converting back to SUA, goal is 33”-35” tires with factory FJ40 axles. This is NOT going to be a hardcore wheeler.

This thread will probably just capture the rolling chassis stuff that we are working on together...
  • Like


6.0 LS in a ‘69 FJ40


IMG_5871.webp



IMG_5866.webp
 
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Augustiron

Build Thread 'Brandi: 75 40 + 5.3 + fj60 H42 + splitcase .... build and lots of questions'

Hi mud brain trust

I would like this to be in relatively open thread where people can post questions and advice from their own LS swaps into 40s, So it can be a goldmine same work.
I have spent countless hours searching and reading various build threads here and garnered a ton of information, thank you to all those who have contributed over the years.

Now that I am starting to place the engine in the chassis I realized there is a bunch of stuff I need to figure out that I haven't seen posted anywhere, So I will have a bunch of questions I hope the brain trust can help with.

I...
  • Like
 
I did my own harness from the stock gm harness. I followed a YouTube that walked through doing one for a CJ, so basically the same concept. He had links to the LT1swap.com diagrams and used them as a reference. Made the whole thing easy.

That being said, it’s time consuming and tedious. So think about how much time you have.

As @Rock40 said this is the tip of the iceberg. There’s a lot more involved with a drivetrain swap. Honestly, modding the driveshaft was probably the easier/ healer part of the project.
 
I also have an LS in my Cruiser, though if you like the 2F then why not swap a 3FE auto onto the 2F, or do the entire 3FE swap?

I wouldn’t personally do that swap because it would be underpowered in the Colorado mountains, but it might be fun in Florida. Don’t let me talk you out of an LS.
 
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You can run an a440F behind your 2F pretty easy, no adapter plate needed, if your goal is just to have an automatic. not sure what year your truck is but if you already have a splitcase even better.
 
Mike Shull said:
I also have an LS in my Cruiser, though if you like the 2F then why not swap a 3FE auto onto the 2F, or do the entire 3FE swap? I believe that Proffitts has done both of these swaps?

I wouldn’t personally do that swap because it would be underpowered in the Colorado mountains, but it might be fun in Florida. Don’t let me talk you out of an LS.
Click to expand...

That's very interesting. I had previously asked in another thread if there was an automatic that I could bolt up to my 2F, or even use an adapter plate but everyone that responded at that time said no. So "if" the transmission from a 3FE would bolt right up than that is definitely something to consider, if I can find one at a good price.

And you may be right about the mountains -Vs.- Florida. Pretty mild down here. But, my dad (he was born in Colorado) used to have a Jeep Cherokee 4wd with a 4 cylinder, and that little engine wouldn't quit! We took it up and over Black bear pass multiple times, and up camping. He had almost 500,000 miles on it when he sold it.
 
TheBussman said:
You can run an a440F behind your 2F pretty easy, no adapter plate needed, if your goal is just to have an automatic. not sure what year your truck is but if you already have a splitcase even better.
Click to expand...

My FJ40 is a 1971 but I have a 2F and 4 speed transmission and transfer case from a 1978.
 
FloridaLife said:
My FJ40 is a 1971 but I have a 2F and 4 speed transmission and transfer case from a 1978.
Click to expand...
The 78 case won't work. need a splitcase, best to get one from a fj62 with the a440f trans cooler lines, gear selector , convert the case from vac shift to manual. I'm guessing the trans tunnel will need to be modified to fit, the auto trans is longer and you will need your driveshafts lengthened/shortened.
 
Rock40 said:
LS swap is fairly straightforward, I did a custom build 6.0 LS in my 40 after running a Vortec 5.7 for 23 years. And it really depends on your fab skills. It IS a lot of work, to do it right as you are more or less replacing the whole drivetrain but it is very doable

You’ll need custom motor mounts and you might as well toss the Toyota trans, IMO, it’s not going to hold up long and there are vastly better options to row gears with.

If you need to go automatic trans for your back a 4L80E is a good option. Advance Adapters will have what you need to adapt it to the transfer case.

You can retain the factory T-case using an adapter from AA.

Go to LT1swap.com You can re-pin a factory harness from a junkyard very cheaply, no need to spend big money on one. PCM programming is $75

This is not an LS but you’d be doing virtually the same thing. An LS is just a SBC with electronics. I’ll probably be setting the drivetrain in next week.

Rock40

Build Thread 'Ed’s Un-Did FJ40'

Un-done, Un-did, who knows 😂 Helping a friends Dad with a ‘71 FJ40 that’s been in pieces 20+ years. So it’s definitely been undone and some of the “Did” by the PO needs to get done again if you know what I mean. Not the first 40 I’ve worked on in pieces, probably not the last either.

Build: Chevy 400 SB (built 20 years ago so hopefully that’s good), NV4500, stock ‘71 transfer, converting back to SUA, goal is 33”-35” tires with factory FJ40 axles. This is NOT going to be a hardcore wheeler.

This thread will probably just capture the rolling chassis stuff that we are working on together...
  • Like


6.0 LS in a ‘69 FJ40


View attachment 4079597


View attachment 4079598
Click to expand...

That looks very nice. Very clean.
 
A currently active build thread with a LS/auto:

SergP

Post in thread 'My kid wanted a Jeep, she's getting a 77 FJ40 LS Swap instead'

JKIII FJ40 said:
Washer bottle installed, I used one from Amazon. Nice and cheap and it works well. I am still playing around with my Dakota digital dash, my oil pressure stopped working. Then it worked and my water sensor stopped working. Then everything worked and now Im back to the oil pressure stopped working again. Ive been emailing back and forth with Dakota, lets see what they have to say this week when they get the update email on whats been happening. I also removed the heated seat switches from the dash, basically redid the wiring moving the switches by the seats. I will install them in the...
Click to expand...
  • Like
 
Wasatch Jay said:
FWIW, there are a number of companies that offer LS conversion wiring harnesses, and of course at different price points. In my opinion, Howell Engine Developments make an excellent harness and their customer service was top notch.

Conversely, I've also used an LS swap harness from BP Automotive. It was lower in price and in my opinion the money "saved" was nowhere near the extra work required. If there is another swap in my future... I will use a Howell harness.

Good luck with your LS conversion!
Click to expand...

When I was planning on using the 2F drivetrain I had decided to go with the Howell fuel injection for the 2F because it cost so much less than the Holley Sniper and people on MUD who have tried it liked it.

I called and spoke with Matt at Howell. Just FYI for anyone else out there considering this, the Howell wire harness is $700, and then you need the ECU flashed. You send it to them, they flash it and send it back, and that's $200.
 
Mike Shull said:
I also have an LS in my Cruiser, though if you like the 2F then why not swap a 3FE auto onto the 2F, or do the entire 3FE swap?

I wouldn’t personally do that swap because it would be underpowered in the Colorado mountains, but it might be fun in Florida. Don’t let me talk you out of an LS.
Click to expand...

@Mike Shull - which LS and transmission did you go with, and which wire harness did you use? And who did the ECU flash? If you don't mind me asking, were they pretty reasonable on price for the harness and the ECU flash?
 
FloridaLife said:
@Mike Shull - which LS and transmission did you go with, and which wire harness did you use? And who did the ECU flash? If you don't mind me asking, were they pretty reasonable on price for the harness and the ECU flash?
Click to expand...
Hi,

I have the 6.2L L92 from a 2008 Escalade, which is a gen IV DBW engine. I have an NV4500 behind that. I am using the factory harness that I trimmed down and I had a local shop do the final tuning. ls1swap did the initial tune.
 
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