Has anyone ever put a 4.0 jeep engine in an A-body? I had a /6 70 dart that I loved and regrettably sold when my kids were little because I didn't have the time to work on it. I miss that car and would like another one. I also have Jeep and was wondering if anyone put the 4.0 in their dart. It would have fuel injection and over drive. 4.0's are plentiful in the junk yard and they're pretty tough engines too. I don't want to race the car, but my wife wants another one for a daily driver. Any comments or suggestions on this pipe dream?

Sounds like fun! Give it a whirl if it fits.

Length shouldn't be a problem but you might have a height issue. And you'll probably have some work to do to get the trans to fit under the floor. What year A-body are you thinking of?

Might want to take a height measurement first.. /6, V8 both have the cylinders angled to reduce height... On the other hand the Aussie Dart has an inline 6 but I believe it is shorter.... But using the 4.0 EFI on a slanty should be pretty easy...

68-72 A-body. I don't have a car. I just had a thought one day, what if I did this.... Re shaping the floor doesn't bother me, nor does fabbing up a crossmember. The height can be managed with a cowl hood, or maybe a six pack hood. Wish I had more time and money...

OR.... You can just put in a 360 with an A-999 trans, use a 2.76 axle ratio and get 20 mpg.
Being different is fun, but being a pioneer also means that your support system is rather limited.

That is an interesting question! I happen to have a 68 Dart sitting next to an 84 CJ7 right now and the front end is off the Jeep, might have to take some measurements!

a 360 that gets 20mpg? I'd like to see that. Is that going downhill with the engine off?

Take some measurements of the engine and engine bay. I wonder if the computer in the 4.0 is learning computer. I've been told the computer in my 3.9 Dakota would adjust the A/F ratio IF I ever put a turbo on it. I wonder if the 4.0 would do the same. I6 is way easier to turbo than a V6 or V8. HMMMMM....

20 mpg is possible. Thats why I mentioned the 999 trans and 2.76 axle. The 999 has the lower first and second gear to maintain better acceleration from a standing start, yet the freeway gear allows low rpm cruising. Some may call it an alternative to overdrive. A well tuned thermo Quad can get a stock 360 in a 3000 lb Dart to 20 mpg.
NO, not all downhill either!

If trying to get gas mileage and using a 999 trans, one of the 2.21 or 2.45 gear sets would be better than a 2.76. The 318 M bodies with these gears would exceed 20 mpg highway. These extreme gears will help highway fuel economy, but will hurt performance.

My Jeep Cherokee with a 4.0 and the overdrive transmission got 19-20 mpg frequently. It had 3.55 gears and was a 4x4. I think the EPA rating for it is only 18 mpg highway though. I tend to drive for economy, so a lot of folks gas mileage probably wouldn't be quite as high.

The 273 V8 is only a little larger than a 4.0 Jeep engine, while the 225 slant six is a little smaller. Either of these would obviously be less work. But since the original poster has a good 4.0 on hand, an engine swap may be a good plan.

The 4.0 is obviously a newer engine than either the 273 or the 225 Mopar engines. The 4.0 has many advantages offered by newer technology. (fuel injection, etc.) I'm going to guess the 4.0 will likly fit in an A-body just fine. The 4.0 is essentially a re-engineered, updated and modified version of the older AMC six cylinder. The Rambler American was quite similar in size to the Mopar A bodies. Since the AMC engine was used in the American, it will likely fit in a Mopar A body. I'm fairly certain that AMC used some 904 mopar transmissions in some of their cars. So it is probable that the 999 gear set could be swapped into the "AMC" version of the 904 transmission and be installed behind the 4.0 engine. This may allow the 904 to bolt into an A-body. (I don't know if the AMC transmission mount is the same as a mopar mount though) It would be important to verify that the transmission used has a lock-up converter if fuel mileage is an important consideration. If it could be made to fit, I'd seriously consider using the Toyota transmission that Jeep used behind the 4.0 in the Jeeps Cherokees. These are overdrive transmissions and seldom give any serious trouble.

I have a feeling height may be an issue, and perhaps getting an oil pan to fit. if you want to stick with 6 cylinders, I think I'd try adapt the 4L's EFI to the slanty, or look for a take out 3.7 from a liberty or GC, a magnum 3.9 (3/4 of a 318), or a 3.8 out of a grand cherokee.

personally, I'd build a 318 magnum similar to hotroddave's "super duper gas mileage 318" in the "best of" section, but using a reground hydraulic roller cam and either adapting the magnum EFI, or putting a carb intake and running a demonsizzler tuned small t-quad on it. or a FAST EZ-EFI.

I built a magnum headed 318 in my 4000 lb 5th ave, with a rerung short block, reground roller cam (259/259 adv, 208/208@.050, .506/.506 with magnum rockers, 112LSA, installed at a 108 ICL), headers, eddie air gap and edelbrock 600cfm carb, and it moved my old 5th ave pretty well, comparable to an early 1st gen 300C AWD from a roll. this was with 3.55's and an A500 OD tranny. in my mixed driving commute I'd get about 17.5mpg. now replace the eddie 600 with a spread bore or better tuned EFI, put it in a car 600-700lbs lighter, and switch to an A833OD with 3.23 gears, I bet you'd have a car well into the 13's that would return 20-21 mpg in mixed driving if you kept your foot out of it, and straight highway mileage close to 25mpg...step up to 0 deck with KB167 pistons, and expect more power and probably even better fuel economy.

my cam was reground by bulletcams.com, they used their HR259/316 lobe. step it down to their HR247/306 (247adv, 192@.050, 112@.2, .306 lobe lift, .490" valve lift with magnum 1.6 rockers) or their HR252/320 lobe (252 adv. 195@.050, 115@.2, .320 lobe lift, .512" with 1.6 rockers) and you might be able to get upper 20's on the highway....

I never thought of a 3.9. I have a 93 Dakota with a 3.9 and I get about 20 in my truck. I wonder how close the 3.9 motor mounts would be to a small block K member in a dart. I don't have a 4.0, but the junkyard nearby is full of them, for little money. Gas mileage and reliability are my main concerns. I have a 69 Charger for fun

the rambler american ran a 232 straight 6---close to same dimensions as the 258----and dont the jeep guys stroke the 4.0 with the old 258 crank to a 4.5---and i thought the jeep 904 really had the first 999 internals or was it 998---bob

I think it would be pretty cool to do the 4.0 swap.

Although they have a little bit less power(177 vs 190hp) I would do the swap with the renix fuel injected 4.0(87-90). That is a very simple EFI system that works well and is easy to work on if it acts up. I also think it would be pretty easy to make the renix EFI and the AW4 transmission controller "stand alone" vs the later fuel injection system.

I wouldn't do this swap expecting to get some crazy MPG but high teens low 20s would be pretty doable. The XJ Cherokees weigh about the same as an A-body and are probably no better or worse off when it comes to aerodynamics.

Its also super easy to build the 4.0 up to a 4.6(281cid) using all stock AMC/Chrysler parts. Mine has about 35K miles on it now and has a nice increase in power but doesn't get any worse MPG than before.

I have a lot of experience with the jeep motor. Jeepstrokers.com is a good resource. The 2000 and up intake is a good gain. 7120 casting head is the best performer. Painless has the best fuel injection computer with the most adjustment for upgrades. The AMC can use the overdrive automatic transmission from a cherokee. They need a piggyback computer to work but they need some patience to install. Tim