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WJ-->MJ??

kaidenlem
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kaidenlem Comanche Fan

kaidenlem

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Just got the idea of purchasing an entire WJ 4.7 drivetrain and entire wiring harness out of the junkyard for a couple hundred bucks and dumping it into an MJ with NOTHING.  The V8s have a 44 rear and 30 front. Just curious if anyone is as stupid as I am and want to try it.  :nuts:

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derf MJ Junkie

derf

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The WJ 4.7 is probably the worst V8 you could choose.  It's big (hard to fit), it doesn't make much power, the transmission behind it is not stellar, and there's basically zero aftermarket supporting them.

 

The rear axle is aluminum (i.e. weak) and I believe the Dana 30 is low pinion.

 

Basically, you're only throwing away money doing this swap.

 

You get more power and reliability out of a stroker 4.0/4.6.  If you're set on a V8 swap, go chevy small block or LS, a Magnum 5.2/5.9, or small block Ford 5.0.

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kaidenlem Comanche Fan

kaidenlem

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11 hours ago, derf said:

The WJ 4.7 is probably the worst V8 you could choose.  It's big (hard to fit), it doesn't make much power, the transmission behind it is not stellar, and there's basically zero aftermarket supporting them.

 

The rear axle is aluminum (i.e. weak) and I believe the Dana 30 is low pinion.

 

Basically, you're only throwing away money doing this swap.

 

You get more power and reliability out of a stroker 4.0/4.6.  If you're set on a V8 swap, go chevy small block or LS, a Magnum 5.2/5.9, or small block Ford 5.0.

I already have one, so that's why I was curious.  I have an 04 and the rear dana 44 is for sure heavy duty and definitely not aluminum.  I've had absolutely no issues whatsoever with the 4.7 non-HO that I've had for almost 3 years.  It never even misfired when the plugs had no electrode left.  But again, it would be crazy cheap to do, wayyyy cheaper than a stroker build and the 4.7 v8 would still have more power than the 4.0 for what I'm going to use this rig for.

 

 

1 hour ago, Pete M said:

there are definitely reasons why there are a whole mess of v8 swaps in the Epic Tech forum and none of them are 4.7Ls.  :(  

Again, never had an issue with mine.  I've had it for 3 years and tens of thousands of miles with NOTHING besides oil changes.  Still will run like the day it came out of the factory.

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Pete M down with the MJ sickness

Pete M

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reliability is only one of the aspects that make it a less desirable choice than the LS.  but I am all for creativity. :L:  take lots of notes and snap lots of photos!  If it's as easy as you hope, maybe it'll catch on :D  Lord knows there are a ton of Grands in the junkyards these days. 

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derf MJ Junkie

derf

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It's still not a good idea.

 

If you're good with a welder and can fabricate everything you'll need, along with being a whiz with adapting all of the integrated electronics, you might make it work.

 

Take lots of pictures.

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89 MJ Obsessive Comanche Disorder

89 MJ

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This would be a very cool build, but I don't think it would be as easy as you think. What are your plans to get the gauges work? What is your plan for deleting all of the unnecessary electronics that you won't use in the MJ?

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89 MJ Obsessive Comanche Disorder

89 MJ

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3 minutes ago, eaglescout526 said:

Why not drop in a AMC 360 or an AMC 401 just to be different. Haven’t seen one of those swaps. 

This would be very cool. Plus they made decent power. The one in my brother's 83 J10 was rated at 245 hp and 365 lb/ft of torque.

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derf MJ Junkie

derf

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The AMC V8 is a bigger engine and it would be a tight squeeze.  And there is only slightly more aftermarket for it over the 4.7 these days.  It would easily bolt to an AW4 or AX15 since it shares the bellhousing with the 4.0 so that would be easier.

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Smokeyyank MJ Junkie

Smokeyyank

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58 minutes ago, kaidenlem said:

I have an 04 and the rear dana 44 is for sure heavy duty and definitely not aluminum.  I've had absolutely no issues whatsoever with the 4.7 non-HO that I've had for almost 3 years.  It never even misfired when the plugs had no electrode left.  But again, it would be crazy cheap to do, wayyyy cheaper than a stroker build and the 4.7 v8 would still have more power than the 4.0 for what I'm going to use this rig for.

 

 

Yes, it is aluminum. All D44s under WJ's are D44A/HD with the aluminum center. The biggest plus it gets is a bigger R&P than a standard 44 beyond that nothing heavy duty about them.  WJ D30's sucks as they are LP and have CV axles instead of u joints. Only decent part is the steering and brakes. Better off building a HP30 with a WJ swap or just going with JK44's or tons. As for the 4.7 the reason they aren't swapped is because they are stupid expensive to rebuild (ask me how I know) and reliability isn't there strong point. So while you have one that may run like a top now it's only a matter of time before you drop a valve seat and get stuck with a dead engine. As for cost if you think swapping in a V8 is cheaper than a stroker you'll find it's not, by the time you fab and figure out cooling along with the mess of the other stuff you'll be way above a stroker and deeper gears cost.

 

Other than just wanting a V8 why even consider it? 

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Sir Sam MJ Maniac

Sir Sam

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Well, swapping in a 4.7 requires the same amount of fabrication as any other engine swap. So the 4L gets points for bolt in. 
 

the rear axle isn’t particularly desirable and doesn’t have tons of aftermarket support, to the point where a ford 8.8 or kJ 8.25 is better and is only $100 at the junkyard. 
 

the front axle is fine, it’s low pinion, which doesn’t matter much, and it’s wider than the XJ axle so the mounting isn’t a direct fit up. So to swap it in you need to do some fabrication, more than let’s say just taking a HP XJ d30 and swapping on WJ steering and brakes. 
 

545rfe trans is just OK, but an AW4 is much much better. 
 

if you had a 242 transfer in your donor you would find it does not have the speedo provision in the tail housing like the xjs and ZJs do, so what do you do about your speedo?

 

do you have the ability to rewire the engine harness, to get the 4.7 to run standalone? I don’t know if anyone makes a plug and play kit and flashes an ECU or not. At the minimum you would want to flash the ECU to remove the security, unless you are well versed in the SKIM system and know how to work around it. 
 

So think about all of that, and then compare what spending just a little more money on a Chevy donor gets you and.......you have nearly all the same trouble, expensive, headache, for a lesser option V8. 

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dasbulliwagen MJ Maniac

dasbulliwagen

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Another NO for the 4.7. I was a dealer tech for several years, and these engines do not tolerate any kind of neglect, and if you overheat it one time, you might as well rebuild it because everything in it will warp, and the valve seats will fall out. Another thing is they are VERY wide, and it would be tight to the inner fenders on the MJ if not impossible to even fit in the engine compartment. As was said, there are lots of better options out there. If you really want to do that much work, Id do a 3.6 with either a NAG1, or an eight speed. Same or better power in a much more reliable and less finicky package.

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