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steveo27
Dodge Dakota
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10/12/2005
19:31:49
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 Subject: swapping 5.2 into a 4wd premag 3.9
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ok. this has been thrown around by me before but im gonna do it again...
i just found a 91 2wd auto (im pretty sure the 91 318 is a premag?)5.2 v8 dakota in the junk yard. it runs. its complete, i can get it pretty cheap.
i wanna put this set up into my 87 4wd pre-magnum 3.9 v6. i wanna swap everything (motor, trans, & fuel injection set up)...
what all will i need off the 91? i know i need to do a gen II front swap or an elecric fan (clearance)
- all the wiring harnesses from the fire wall forward?
- computer?
- 5.2 radiator?
- will the new tranny bolt to the transfer case? (or can i get away with bolting the 318 to the old 3.9 tranny)
- how bout motor mounts?
- will i have to use the serpentine belt setup, or can i switch it to the 3.9?
anything else i should know???
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gen1dak
Dodge Dakota
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10/13/2005
00:17:13
|  RE: swapping 5.2 into a 4wd premag 3.9
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You'll need a crossmember for the 5.2 engine mounts.
http://www.engine_swaps.com
It wasn't til the Magnum that the V8's gained the ability to bolt in like the 3.9 did.
There is no serpentine on pre-mags. If the '91 has it, it's either aftermarket serpentine, or maybe a late '91 that got an early Magnum??? Maybe it's really a '92???
The pre-Mag 3.9 and 5.2 share accessory drive set-ups, belts, etc.
They also have the same bolt patterns for the tranny bellhousing, and the torque converter will work.....as long as this is not a Magnum.
Also, you can't bolt the 2WD tranny to the 4WD setup unless the 2WD tranny gets a 4WD output shaft and 4WD housing.
Wiring harness and computer...yes. Fuel pump...yes. Along that topic, probably best to grab the fuel tank too. Or, keep your tank count on adding a high pressure in-line fuel pump to your stock '87 setup. You already have the fuel return line, so that's one less headache. The TBI doesn't require as much psi as the Magnum, but still quite a bit more than with a mechanical pump.
The V6 and V8 Dakotas shared the same radiator, so unless the '91 looks better, or perhaps is bigger due to a towing package (yes, it was available, despite Dakotas never being famous for their towing abilities), you're safe with the stocker in your '87.
The electric fan is much easier and cheaper than a front cap swap.
V8 exhaust.
Some say get the V8 springs, but when Carroll Shelby made 1500 '89 Shelby Daks (the only V8-powered Gen 1 Daks from the factory), they used a stock V6 Sport suspension with gas-charged shocks. No other mods.
For tranny longevity, add the TransGo kit.
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steveo27
Dodge Dakota
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10/13/2005
02:07:08
| RE: swapping 5.2 into a 4wd premag 3.9
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alright. im gonna go back and look at the motor again soon. i was told it was a 91. im gonna check the vin and see if i can figure out for sure. it looks like a magnum tho. is there any easy way to find this out?
engine-swaps.com sells motor mounts for a 2wd swap, not 4wd.
the serpentine set up looks like the stock set up on the mag 5.2s.
so the magnum 5.2 will not bolt to a 904 tranny?
will i be able to switch over to the 5.2 throttle body, or will i have to replace the manifold and run a carb?
i plan on doin a gen II front swap anyway.
the 4wds have torsion bars, not springs. i plan on replacing them with v8 torsion bars.
any one else?
thanks
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Mark
Forum Moderator
10/13/2005
11:54:18
| RE: swapping 5.2 into a 4wd premag 3.9
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I like the picture of the dakota on engine-swaps.com. haha
She looks slightly different now. That picture was from about 4 years ago.
-Mark Hryckiewicz
1993 Sport RC SB 5.2L Auto
Mark.DodgeDakotas.com
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gen1dak
Dodge Dakota
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10/13/2005
20:47:07
| RE: swapping 5.2 into a 4wd premag 3.9
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4WD....Sorry, I forgot about that on the crossmember thing.
Ditto on the torsion bars. 4WD isn't an area I've gotten into much.
The Magnums have the same bolt pattern for the tranny, so it will work. The problem is in trying to bolt a 2WD tranny to a $WD setup. The output shafts are different lengths.
If a Magnum V8, it'll bolt in just like you V6 is now.
Now, if it's a Magnum, but you're gonna run a carb, you don't need the wiring harness or computer. All you need is the Mopar Performance electronic ignition kit.
Do you have an electric fuel pump now? If not, you'll need an inline pump for carbs. These make less pressure to work with carbs.
If it's a Magnum 318, your V6 converter and flexplate will bolt right up. Since going carb, you won't need the Magnum converter (for the MPI). Any zero-balance converter will work on carb applications.
The stock Magnum intake manifold is strictly for MPI. If you could even get a carb to bolt on, it'd run poorly. So, get the Performer RPM for Magnum or the dual plane Magnum M1 from Mopar Performance.
A couple quick visual cues....Valve covers...The Magnum has 10 bolts per cover. Pre-Magnum covers use 5 bolts.
As mentioned, the LA's (pre-Magnums) use V-belts. Magnums use a single serpentine belt.
The TBI LA engines use true throttle-body injectors (the 2 fuel injectors are in the throttle body), while all Magnums use multi-point injection. There are 8 injectors. Magnums have 2 fuel rails, one on each side feeding those 8 injectors. The Magnum throttle body has no injector function, just air handling. The intake manifold on an LA has bolts that thread into the head at an angle. The Magnum intake bolts go straight down into the head. The Magnum has a tall "beer barrel" style intake. The Magnum also has a much more streamlined exhaust manifold setup. If it is a '92 Magnum, either keep the stock exhaust...or sell 'em to me.....cheap! :-) They're better than the mid-'93 and later ones. They flow better.
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Super bee
GenI
10/14/2005
01:59:06
| RE: swapping 5.2 into a 4wd premag 3.9
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so has anyone actualy found an aftermarket fan that will work for this yet? i mean so i dont have to move crap around
im onyl a week or 2 away from putting the 5.2 mag in
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steveo27
Dodge Dakota
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10/14/2005
02:00:56
| RE: swapping 5.2 into a 4wd premag 3.9
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well i went and looked at the motor again today..
heres what i found
some info on the truck in the junk yard...
- its a 91, (manufacture date : 2 / 91)
- the VIN number is : 1B7GL23Y8MS283549
- the motor has the coil on the firewall
- it has the numbers 6089 & 572 on the valve covers
- it has a serpentine belt setup.
- the motor mounts are under the center exhaust ports
- it has a throttle body with 2 injectors in it (no multiport).
- it is connected to an A500 (push button over drive)
i will get pics of the motor ASAP
-----------------------------------------
I was looking at my truck tonite. i noticed that the motor mounts are under the front 2 (doubled) exhaust ports, which is the same location where the motor mounts are on the 5.2. (the middle exhaust ports). so technically it should drop in?
the have the motor mounts in the same locations,
This is what really confused me. i was always told that the ears for the motor mounts on the premag 5.2s were on the front of the block under the 1st set of exhaust ports. this motor has them under the middle 2 exhause ports. and it has a serpentine belt set up, which is consistant with a mag 5.2.
as for the tranny, if its not a magnum, the 904 should bolt right on since the premag 3.9 and premag 5.2 are the same blocks (the 3.9 just has the front 2 cylinders chopped off)?
the front belt set up from the 3.9 should swap over too b/c they are techincally the same motor?
if it is a premag 5.2, i can run any aftermarket manifold to swap over to a carburator?
i can run a MP electric ignition kit or any points style set up to fire the plugs correct?
if i run the carb, i wont need the wiring harness (the 3.9 and 5.2 premags harnesses are almost identical i was told)?
also if its a premag 5.2, all the fuel system should be the same if i run the carb? i know the fuel pump part numbers cross reference.
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steveo27
Dodge Dakota
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10/14/2005
02:04:06
| RE: swapping 5.2 into a 4wd premag 3.9
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superbee, you have any pics?
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Super bee
GenI
10/14/2005
09:40:03
| RE: swapping 5.2 into a 4wd premag 3.9
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not as of yet, i dont have it in the truck yet :)
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steveo27
Dodge Dakota
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10/14/2005
12:41:38
| RE: swapping 5.2 into a 4wd premag 3.9
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alright. let me know when you do!
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gen1dak
Dodge Dakota
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10/14/2005
20:00:57
| RE: swapping 5.2 into a 4wd premag 3.9
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The only thing I can figure is either Mopar had started using the Magnum blocks (but not the heads, etc) before the model year kicked over to 1992, and had phased the Magnum engine mounting in as well, or that Dak has a replacement block of the Magnum variety. Somewhat of a mystery.
Are you absolutely sure that throttle body has injectors in it? Doesn't make sense.
On the tranny, Magnum or LA, the 904 will bolt up. The only problem involves using the MPI. Going carb takes care of that.
The water pump and all accessory drives, pulleys, etc will swap over. On a factory Magnum serpentine setup, the water pump and fan turn opposite of the engine, on an LA, they turn the same as the engine, so don't try to mix-and-match parts. Swap all the V6 stuff and you're fine.
You can run any pre-Magnum intake manifold ('67-'92). One thing to consider is that the pre-Mag 5.2 has smaller intake and exhaust ports than the 340/360, so while any LA intake will bolt on and work, you'll get a lot of flow-impeding turbulence and poor low-speed power, so unless you're gonna swap to 360 heads as well, best to stick with the standard Edelbrock Performer intake manifold. The others all have the larger 360-sized ports.
Running a carb means no need for the harness.
Correct on fuel system. Your stocker is fine.
Ignition. Anything you want.
On the engine mounts, from what you've described, it should drop right in. You need to take some picturs of that donor truck. If all original, it's one rare bird.
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steveo27
Dodge Dakota
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10/14/2005
20:34:33
| RE: swapping 5.2 into a 4wd premag 3.9
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alright. ya i was really confused too on what it was. it looks like the magnum block but premag valve covers and heads and yes, im sure, it has 2 injectors in the throttle body.
im gonna go up tomorrow and get you pics. can you decode the VIN?
so the 3.9 harness is exactly the same as the 5.2?
o another thing that may help identify it is that the charcol canister is mounted on the fenderwell.
do you think its worth pulling for 250$. it has 200K miles on it, but it runs strong. i plan on doing a top end rebuild. what do you think?
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Super bee
GenI
10/15/2005
00:41:44
| RE: swapping 5.2 into a 4wd premag 3.9
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my donor had 107k on it when it was rolled
and today i pulled the engione out of my 1990, fuc|:-|
so im going to pull one from the 1995, i tore up the rubber part becuase i took out thew wrong bolt, that was a big F*%K
i havea new water pump and a new idler pully for the 1995 because the fan got bent, and i dont wanna risk the water poump being screwed, and the one pully was bent
$100 later that will be all fixed, and i want to put in the headers and all that tomorrow
SO, also the 22 gallon gas tankl and the wiring running to it, hopefully in 2 weeks i can see if it will start, i hope i hope i hope
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gen1dak
Dodge Dakota
JOIN HERE
10/15/2005
18:00:06
| RE: swapping 5.2 into a 4wd premag 3.9
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The Vehicle Identification Number 1B7GL23Y8MS283549 is from a 1991 Dodge Truck with a Club Cab body and a 5.2L (318ci) EFI V8 engine. It has a GVWR of 5001-6000 lbs. and was vehicle number 283549 to be built on the Dakota, Dakota Shelby, Dakota Sport, Dakota 4x2 line at Dodge City Assembly (Warren, MI), USA.
This is courtesy of: http://www.dakota-truck.net/
Okay, so that's the story. Looks like they did phase in the Magnum-style blocks and engine mounts a little early.
Now, on the engine harness, there will be some minor differences due to the difference in years, but primarily, it's due to the addition of the fuel injection. Otherwise, very little if any changes, and minor at that. SInce you're going carb, you eliminate all the FI-related wiring. What's left should be easily adaptable. Looking at the alternator from a 2001, for example, a pulley swap and a slightly different wiring connector and it'll be right at home onan 80's Dakota. They make it look like it's totally different, but down to the core systems it's the same stuff.
$250 seems high to me, especially if I had to pull it myself. It may run well enough, but at 200K, it's gonna need work before long. Your call.
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steveo27
Dodge Dakota
JOIN HERE
10/15/2005
19:35:05
| RE: swapping 5.2 into a 4wd premag 3.9
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alright thanks.
between 200 - 250$ and hes gonna pull it for me. that includes the motor, the wiring (even if i dont need it), exhaust manifolds, Y pipe, ect.
i plan on rebuilding it. and so far this is the cheapest and cleanest motor i have found. everything else is pre 85 and has the different motor mounts. i dont mind dropping a few extra $$ since the motors gonna drop in and i dont have to waste my time making motor mounts...
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Super bee
GenI
10/17/2005
14:23:31
| RE: swapping 5.2 into a 4wd premag 3.9
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so do you have an answer for the fan problem?
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steveo27
Dodge Dakota
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10/17/2005
15:19:08
| RE: swapping 5.2 into a 4wd premag 3.9
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the fans out of the dodge vipers are really good. theres a guy on sounddomain that has one in his. if i find the write up ill send it your way.
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gen1dak
Dodge Dakota
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10/18/2005
01:14:49
| RE: swapping 5.2 into a 4wd premag 3.9
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Why not use a Flex-a-Lite Black Magic electric fan? They have single units that pull up to 2,800 cfm, and dual units that pull as much as 5,500 cfm.
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Super bee
GenI
10/18/2005
11:11:38
| RE: swapping 5.2 into a 4wd premag 3.9
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but how thick are they?
how thiock was the one you pulled out of your shelby?
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jayb
Dodge Dakota
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10/18/2005
12:17:34
| RE: swapping 5.2 into a 4wd premag 3.9
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to make your life easy, put that front end off the 2wd with the v8, on your 87. it will fit easier, and look better. why wouldnt you go magnum? the old LA's had good low end grunt, but no peak hp at all. even the torque is less than the magnums. LA's were 170hp and 260tq. magnums are 230hp and 295tq. if your gonna do all that work, at least make the best of it.
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Super bee
GenI
10/18/2005
14:16:58
| RE: swapping 5.2 into a 4wd premag 3.9
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im doing a 1995 magnum, not sure if i would even want an old LA, becuase its going to be a pain jsut doing the swap, i at leasyt want to get some power out of it
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