Jeep 4.0 into a Willys?

MrFreeze5

Bigger Hammer
Mar 2, 2010
124
Denver, Co
Willys Model
Willys Year:
Recently the transmission in my 96 Grand Cherokee became FUBAR'd. So I have been forced to use the Magnum V8 and transmission I wanted to use in the Willys in the ZJ. Ive since pulled the old stuff out, engine, tranny, wiring harness, etc. Ive also pulled out the entire interior and dash wiring harnesses to swap out for a Limited interior. But now that I have the entire wiring for the vehicle, and a good 4.0 engine just sitting there, I am tempted to put it in my Wagon. Id need a new transmission of course, but otherwise, pretty much everything is there that I would need. I plan on swapping in all this wiring to the Wagon anyway, and can use most of it with either a I6 or V8.

With the way my firewall has been sectioned back, and the fact that this engine has the distributor on the side, it should clear just fine, but I have no idea what the stock engine measurements were. The engine is a bit on the long side, but I KNOW the magnum V8 fits fine in the Wagon, so the 4.0 should too since they were both options on my ZJ. I dont have my V8 on hand ATM, so I cant measure the difference, but I think it will work. I havent been able to find any other swaps using this engine, which surprises me a little.

Im looking for ideas and opinions here. I originally wanted to use a V8 in the Willys, just because, but putting it in the ZJ is probably a better idea since it is more suited for the power and towing duty. I already have the 4.0 which is a big plus. If I need to go hunting for a new engine/tranny/wiring/etc, it could take me a long time to get it all. I like recycling parts from my other Jeeps too, keep it in the family. Plus this engine is so simple and reliable, I think it would be fun. Opinions?

My ZJ Overhaul Pics
 

Pete

Founder/Owner
Staff member
Administrator
Sep 17, 2009
6,496
Hailey, Idaho
First Name
Pete
Willys Model
Wagon
Willys Year:
1960
Damn, I gotta get this picture size limitier thing figured out... When the pics are wider than 800 pixels, they blow the page formatting outside of the margins... Any way you can resize your pics so we can read the text?

Thanks,

Pete
 

MrFreeze5

Bigger Hammer
Mar 2, 2010
124
Denver, Co
Willys Model
Willys Year:
Pete said:
Damn, I gotta get this picture size limitier thing figured out... When the pics are wider than 800 pixels, they blow the page formatting outside of the margins... Any way you can resize your pics so we can read the text?

Thanks,

Pete

This is the only forum my pictures go crazy on. And resizing has not seemed to help in the past unless they get shrunk way down. Ive also used different photo hosting and they still look weird on this forum.
 

Pete

Founder/Owner
Staff member
Administrator
Sep 17, 2009
6,496
Hailey, Idaho
First Name
Pete
Willys Model
Wagon
Willys Year:
1960
MrFreeze5 said:
This is the only forum my pictures go crazy on. And resizing has not seemed to help in the past unless they get shrunk way down. Ive also used different photo hosting and they still look weird on this forum.
I've dispatched the highly trained team of monkeys to get this sorted. If I turn on the size limiter, it won't let any images post. If I turn it off, images that are wider than 800px blow the format. Stay tuned, working on the fix. Thanks for your patience-

Now back to your topic...

Pete
 

MrFreeze5

Bigger Hammer
Mar 2, 2010
124
Denver, Co
Willys Model
Willys Year:
Pete said:
MrFreeze5 said:
This is the only forum my pictures go crazy on. And resizing has not seemed to help in the past unless they get shrunk way down. Ive also used different photo hosting and they still look weird on this forum.
I've dispatched the highly trained team of monkeys to get this sorted. If I turn on the size limiter, it won't let any images post. If I turn it off, images that are wider than 800px blow the format. Stay tuned, working on the fix. Thanks for your patience-

Now back to your topic...

Pete
:thumbup: for trained monkeys!!
 

Eric B

Precision Fit
Nov 27, 2009
841
Colorado Springs, CO
First Name
Eric
Willys Model
Other
Willys Year:
Other
Pics issue aside.

The 4.0 should be a good fit. Just make sure to run the electric fan for radiator clearance.....

I don't know how big the engine mount spacing is on the 4.0. I can say that the Novak Conversions motor mount kit for the wagons (ford engine) fit like a champ. Once getting em in place all settled in just like I planned it.

Still scratching my head on how I pulled off my 1st ever driveline setting with some string, nut, level, and angle guage.
 

claybobcustoms

Bigger Hammer
Apr 26, 2010
49
Paragould, AR
Willys Model
Willys Year:
I'm planning to do the 4.0 swap also. I havent been able to find any info on it but i know where there's a will there's a way. I'll be starting my swap before long and I will keep everyone posted on everything i run into with it
 

MrFreeze5

Bigger Hammer
Mar 2, 2010
124
Denver, Co
Willys Model
Willys Year:
My engine is already set up for an efan. Ive been running a taurus fan for about 5 years now, so thats an easy swap and was already on the list. In fact, all my vehicles have been converted to efans. Another nice thing is that I replaced the 4.0 motor mounts about 5 miles before my transmission went out. And on the ZJs, the mounts bolt to the frame. So all I really need to do is make an adapter of sorts on the frame to be able to mount the stock ZJ mounts to. Since the ZJ was available with the 4.0 and 5.2/5.9, there is an intermediate mount that bolts to the frame. Im going to take some measurements tomorrow since the willys and ZJ are about 5 feet apart right now. I think it will be a nice fit.
 

Eric B

Precision Fit
Nov 27, 2009
841
Colorado Springs, CO
First Name
Eric
Willys Model
Other
Willys Year:
Other
Keep us posted. I did the cardboard template for my frame boxing plates and a local fab shop cut em and shaped them to the cardboard for me for 30 bucks....
 

MrFreeze5

Bigger Hammer
Mar 2, 2010
124
Denver, Co
Willys Model
Willys Year:
Eric B said:
Keep us posted. I did the cardboard template for my frame boxing plates and a local fab shop cut em and shaped them to the cardboard for me for 30 bucks....

Wow? Really? Thats not a bad deal at all. I was going to cut all mine myself, but it is going to be a real PITA. $30 is totally worth it to let someone else do it :D

I just measured the frames and the ZJ is right at 24" inside where the mounts bolt to the unibody. The Willys is a little under 28", so I should have more than enough room to set the engine in there so long as it fits front to back, which I think it will.

The ZJ mounts:
http://i869.photobucket.com/albums/ab25 ... mounts.jpg
 

silicond17

Precision Fit
Nov 18, 2009
692
Clearwater, FL
First Name
Garrett
Willys Model
Wagon
Willys Year:
1961
I'm very interested in this swap and would love to see it work. It's also nice to see people keeping it real with the Jeep hardware. I think the main reason that so many people go with GM or Ford motors is that they are much more popular, and you have almost infinite choices when it comes to transmissions and transfer cases. For the newer 4.0L I6 you're going to be limited to a handful of manual transmissions, and a few automatics. For Christ's sake, stay away from any Chrysler electronically controlled transmission. If I were in the same boat, I'd be running the 4.2L 258 I6 bottom end with a newer 4.0L I6 HO head. It will be carbureted, with no sensors or computers to worry about. Not to mention, you'll have a much broader choice of transmissions and transfer cases. If you wanted an automatic, you could also go with the Chrysler TF727, in my opinion one of the best automatics out there to use. I've seen 258s sell for $50-100 and up. I even got one for free one time on trade for some spare CJ parts I had left over.

The other issue is making the AMC I6 fit in the engine bay. The original L-226 flathead I6 is a long motor, but the AMC I6 is even longer. I can take measurements of the L-226 if you want; I now have 1 in my wagon, and 1 torn down in my garage. You will have to run electric fans, but you may even have to resort to a pusher fan on the front of the radiator. If you look at the grill mounts for the radiator, you can see that the radiator can probably be pushed farther into the grill a few inches if necessary. I run the V6 Contour fans on my CJ with the 258 I6. The V6 Contour/Mystique fans are dual fans and will pull considerably more air than the Taurus fans in my experience. They fit on my 3 core radiator with a little trimming. On my wagon with the 226, I'm planning on running a pusher fan on the front of the radiator that I can turn on via a switch inside. I already have a fan shroud made for the mechanical fan.

I guess the major thing is to make sure you get all your measurements done before you have at it. I'd make sure it's going to fit before going to too much trouble, but personally I think you can make it work.
 

MrFreeze5

Bigger Hammer
Mar 2, 2010
124
Denver, Co
Willys Model
Willys Year:
silicond17 said:
I'm very interested in this swap and would love to see it work. It's also nice to see people keeping it real with the Jeep hardware. I think the main reason that so many people go with GM or Ford motors is that they are much more popular, and you have almost infinite choices when it comes to transmissions and transfer cases. For the newer 4.0L I6 you're going to be limited to a handful of manual transmissions, and a few automatics. For Christ's sake, stay away from any Chrysler electronically controlled transmission. If I were in the same boat, I'd be running the 4.2L 258 I6 bottom end with a newer 4.0L I6 HO head. It will be carbureted, with no sensors or computers to worry about. Not to mention, you'll have a much broader choice of transmissions and transfer cases. If you wanted an automatic, you could also go with the Chrysler TF727, in my opinion one of the best automatics out there to use. I've seen 258s sell for $50-100 and up. I even got one for free one time on trade for some spare CJ parts I had left over.

The other issue is making the AMC I6 fit in the engine bay. The original L-226 flathead I6 is a long motor, but the AMC I6 is even longer. I can take measurements of the L-226 if you want; I now have 1 in my wagon, and 1 torn down in my garage. You will have to run electric fans, but you may even have to resort to a pusher fan on the front of the radiator. If you look at the grill mounts for the radiator, you can see that the radiator can probably be pushed farther into the grill a few inches if necessary. I run the V6 Contour fans on my CJ with the 258 I6. The V6 Contour/Mystique fans are dual fans and will pull considerably more air than the Taurus fans in my experience. They fit on my 3 core radiator with a little trimming. On my wagon with the 226, I'm planning on running a pusher fan on the front of the radiator that I can turn on via a switch inside. I already have a fan shroud made for the mechanical fan.

I guess the major thing is to make sure you get all your measurements done before you have at it. I'd make sure it's going to fit before going to too much trouble, but personally I think you can make it work.

Since I plan on reusing a lot of the grand cherokee wiring through the whole truck, it somewhat limits what I can do. I will have the same electronic constraints as if I were doing the swap on another grand. The engine is a 96 OBD2 HO engine that is currently set up with a 42re transmission. Im not a big fan of these trannys either, but I can find one cheap and it will plug and play with what I have, which is a plus. Or I can convert to a AX-15 without too much trouble, but I want to keep it auto. I have always run a cooler on my 42re and it never slipped, the only problem I ever really had out of it was a leaky pan gasket, and eventually a crack at the cooler line fitting, which I contributed to not paying attention. This engine is all stock except for bolt on mods, so the stock auto can handle it so long as its maintained. I have most of what I need from the donor truck, radiator, transmission cooler, taurus efan, etc. If you look in the pics of the front of the engine, youll notice the water pump pulley, which does not have a fan clutch attached to it. And the efan is kinda peeking out in one pic. I have been considering some of the dual fans for this, but in my ZJ there wasnt room. I did pick up a set of dual fans recently from an intrepid I think for my Comanche with its long thin radiator. Im a big Efan fan :D

The part that is really encouraging me to do this is the work the previous owner did on my Willys. An AMC 304 was swapped in, it looks like a LONG time ago, but he did pretty good work. The best part is that the firewall was sectioned back about 3" to clear the engine. This will give me extra room front to back.

http://img.villagephotos.com/p/2010-3/1 ... %20cut.jpg
http://img.villagephotos.com/p/2010-3/1 ... diator.jpg
http://img.villagephotos.com/p/2010-3/1354553/empty.jpg

When the PO did the V8 swap, he also swapped in a 27" radiator. Its the same size as the one that was on my ZJ, so I think cooling will work out fine. Plus the engine has a brand new water pump, and a low temp thermostat. And I do have a new 10" pusher fan sitting in the basement in I need it for anything.

As soon as I can get my ZJ out of the way(itll be a few weeks) Ill hoist the engine and tranny into the Willys and see how it fits loosely while I can get it in and out easily.
 

MrFreeze5

Bigger Hammer
Mar 2, 2010
124
Denver, Co
Willys Model
Willys Year:
silicond17 said:
I'm very interested in this swap and would love to see it work. It's also nice to see people keeping it real with the Jeep hardware. I think the main reason that so many people go with GM or Ford motors is that they are much more popular, and you have almost infinite choices when it comes to transmissions and transfer cases. For the newer 4.0L I6 you're going to be limited to a handful of manual transmissions, and a few automatics. For Christ's sake, stay away from any Chrysler electronically controlled transmission. If I were in the same boat, I'd be running the 4.2L 258 I6 bottom end with a newer 4.0L I6 HO head. It will be carbureted, with no sensors or computers to worry about.

I do plan on one day building this engine into a stroker. In fact, its already in the works, but if I try and build it now, it will be a long time before it makes it into the Willys. Plus this engine runs great and is in fantastic shape overall, and I know its history well, Ive been driving it for the last 8 years. Once it goes out, then it will get the full treatment, but I dont suspect that will be for a while. Which is OK, because with the mods I had for my engine, I was putting out about the same numbers as the 5.2L I wanted to put in anyway, and I can be a bit freer with mods since this truck is emissions exempt. I havent decided what kind of engine management I will use considering all I have on hand with my small Jeep fleet, but thats a project for another time. I just want to get the thing drivable, and this 4.0 has been a super reliable engine that I know like the back of my hand. And so long as I can find another decent tranny to start with, since Im not wheeling this rig, or doing major towing with it now, it should be just fine.

Today I picked up a new valve cover gasket for my Comanche 4.0, Ill use the box as a rough reference since its a lot easier to move around than the engine :D
 

silicond17

Precision Fit
Nov 18, 2009
692
Clearwater, FL
First Name
Garrett
Willys Model
Wagon
Willys Year:
1961
Well that's good news then. It's interesting the PO had the AMC 304 V8 in there. When the I6 CJ guys swap to the 360 and 401 (same mounts as the 304), we only have to change 1 motor mount; I forget if it was passenger or driver side. It should be pretty easy to get your I6 mounted in that case. Also, with as much clearance as you have with the 304 judging from those pictures, I believe you'll be fine.

I'd have to recommend against running the 42RE. It is a very poor transmission to say the least. There are so many problems it had from the factory due to sorry wiring, poor computers, and awful solenoid pack design. When I last had my 41TE rebuild in my daily driver, the transmission shop showed me the drum and planetary gears that grenaded in a 42RE out of a Wrangler. I have to say, Chrysler may as well have made these things out of plastic. On that note, the solenoid pack has plastic in the valve bodies, which is also known to melt and fail at high operating temperatures. The 32RH was used on some 4.0L I6 Jeeps, and it's an excellent and very durable transmission, but it doesn't have an overdrive. The newer ones do have a locking torque converter though. I'd give up the overdrive any day to run a hydraulic transmission instead of an electronic one.

On a side note, why are you pulling the 304? Is it in OK running condition? I know the 304 is nothing to write home about, but seeing that all the mounting work is done, you can easily swap in an AMC 360 or 401 V8 with the better flowing heads. They're pretty easy to come by due to the fact that there are so many full-size Jeeps junked nowadays. I don't know what kind of transmission or transfer case the PO had, but if it's an automatic it's probably the TF727/TF999 or GM Turbo 400.
 

MrFreeze5

Bigger Hammer
Mar 2, 2010
124
Denver, Co
Willys Model
Willys Year:
silicond17 said:
Well that's good news then. It's interesting the PO had the AMC 304 V8 in there. When the I6 CJ guys swap to the 360 and 401 (same mounts as the 304), we only have to change 1 motor mount; I forget if it was passenger or driver side. It should be pretty easy to get your I6 mounted in that case. Also, with as much clearance as you have with the 304 judging from those pictures, I believe you'll be fine.

I'd have to recommend against running the 42RE. It is a very poor transmission to say the least. There are so many problems it had from the factory due to sorry wiring, poor computers, and awful solenoid pack design. When I last had my 41TE rebuild in my daily driver, the transmission shop showed me the drum and planetary gears that grenaded in a 42RE out of a Wrangler. I have to say, Chrysler may as well have made these things out of plastic. On that note, the solenoid pack has plastic in the valve bodies, which is also known to melt and fail at high operating temperatures. The 32RH was used on some 4.0L I6 Jeeps, and it's an excellent and very durable transmission, but it doesn't have an overdrive. The newer ones do have a locking torque converter though. I'd give up the overdrive any day to run a hydraulic transmission instead of an electronic one.

On a side note, why are you pulling the 304? Is it in OK running condition? I know the 304 is nothing to write home about, but seeing that all the mounting work is done, you can easily swap in an AMC 360 or 401 V8 with the better flowing heads. They're pretty easy to come by due to the fact that there are so many full-size Jeeps junked nowadays. I don't know what kind of transmission or transfer case the PO had, but if it's an automatic it's probably the TF727/TF999 or GM Turbo 400.

The 304 that was in there had been sitting for years and I had no desire to rebuild it. It had a T15 3 speed attached to it and no transfer case. I have a 96 Magnum 5.2L V8 and 44re thats all rebuilt and ready to go that I was going to use in the Willys, but my 42RE developed a crack and I decided to go ahead and put the V8 in the grand cherokee. But in anticipation of using the 5.2, I cut the old mounts off the frame. I originally had different plans, but circumstances changed and the V8 has to go elsewhere. So now Im just trying to reuse what I have on hand and can make work simply. Plus, switching to a mopar V8 from this engine will be very simple since I am also reusing the ZJ crossmember, which works for both the 6 and 8 cyl. I only want to use a fuel injected engine, I dont want to bother with carbs, and aftermarket FI costs as much as a complete engine that was FI to begin with.
 

Truckedup

Sharpest Tool
Jul 11, 2010
289
Western NY state 315 er
Willys Model
Willys Year:
This is interesting...I just measured the 4.0 in my 99 XJ,30 inches from the front tip of the water pump pulley to the rear of the head. Measuring the F head engine from the rear of the head to 30 inches foward winds up aboput 3 inches in front of the existing stock radiator location.Probably not a problem,but looking unerneath it appears the 4.0 oil pan will hit the front axle at normal ride height. I think this can be an issue unless the vehicle is lifted???
 

MrFreeze5

Bigger Hammer
Mar 2, 2010
124
Denver, Co
Willys Model
Willys Year:
Progress is SLOW on this one this year. I have to finish my ZJ first before I really get into the Wagon, but it will get a little attention when I have some extra time. Im running spring over in the front, so oil pan clearance shouldnt be an issue. Ive been looking at the engine and at the Wagon, and it looks like because the hood is so high in relation to the frame, the engine should tuck right in nicely between the frame. And since my firewall is sectioned back, I am sure I wont have any clearance issues there.

So far, I have decided for sure to use the 4.0 in this build. I am going to ditch all the electronics though and run a Clifford 6=8 manifold and carb it. And later down the road, the engine should get stroked, and I have a turbo that would be PERFECT for this, but Im not ready to get involved in that right now.
 

silicond17

Precision Fit
Nov 18, 2009
692
Clearwater, FL
First Name
Garrett
Willys Model
Wagon
Willys Year:
1961
That sounds like a good idea to me. I'll take a good ole' Holley carburetor over fuel injection and its slew of electronics any day of the week.
 
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