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90 Dak
Dodge Dakota
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4/18/2002
20:06:00
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 Subject: rebuilding 3.9
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I have been reading this site for a few months now and have enjoyed all the tips and tricks you guys have offered. I am the proud owner of a 1990 dakota 4wd with 252,000 miles. The truck is in great shape and has the original engine. Of course it is starting to get a little tired. I am planning on keeping this truck but I would like a little more power. This truck has TBI injection and is not a magnum. I have looked at the V-8 swap and possibly a V-6 magnum swap but both would appear to be an electrical nightmare even with a donor truck. I am wondering if I could get a magnum V-6 and still use my TBI with new V-8 injectors for more fuel delivery. I have found these injectors at a local NAPA and they do fit my throttle body.I know I would have to plug the mpi ports. Do you think that the magnum heads would give any more ponnies? Also I would like to bore my block and possibly deck the heads for a little more compression. I will ultra-sound the block for thickness to see how much I can bore. Again what do you guys think? I do have a set of headers that I purchased last fall and have gutted the cat but really didn't see any gains. Any help for this old pre-magnum girl would be greatly received. There seems to be ton of things for the magnums but not for these engines.
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Joe E.
Dodge Dakota
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4/19/2002
18:40:14
| RE: rebuilding 3.9
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Hey, an pre-mag girl. Like that.
I gotta 1990 2wd V6. Also intrested in the same thing. Any info would be nice. Espically cam/lifter info.
Joe E.
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Lesley
GenIII
4/19/2002
18:55:16
| RE: rebuilding 3.9
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Look for a guy on here called dodgeboy or dodgeboy93. He is really knowledgeable about rebuilding pre-magnums.
97 3.9 CC Sport. Black. Auto 3.55, Quick D Intake, JBA Stainless headers, Autolite 3923s, stainless Borla Turbo XL, V8 TB, FMS 19 lb fuel injectors, Brass cap & rotor, JBA 9mm cables, Borla tip, IAT adjuster. Coming: Boyd Smoothies
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Joe E.
Dodge Dakota
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4/19/2002
18:59:11
| RE: rebuilding 3.9
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Thanks Leslie.
Your quite good at this too I have heard. But obviously on Gen III stuff since you got that awsome Dak. thanx for the help.
Joe E.
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Lesley
GenIII
4/19/2002
19:03:27
| RE: rebuilding 3.9
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Thanks Joe. I'm just really good at listening to people who know more than me :)
97 3.9 CC Sport. Black. Auto 3.55, Quick D Intake, JBA Stainless headers, Autolite 3923s, stainless Borla Turbo XL, V8 TB, FMS 19 lb fuel injectors, Brass cap & rotor, JBA 9mm cables, Borla tip, IAT adjuster. Coming: Boyd Smoothies
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Joe E.
Dodge Dakota
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4/20/2002
22:16:07
| RE: rebuilding 3.9
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hey, what ever works girl... Keep what ever you are doing up. Its impressive.
Joe E.
come on people, give us old Daks some help.
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TigerDak
Dodge Dakota
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4/20/2002
23:15:21
| RE: rebuilding 3.9
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If you get a new Magnum V6, what is the point to using the older Generation I TBI??? Might as well hook it all up together, including the computer and harness, in one big shot. You might have a chance of the Gen II TBI fitting, but I doubt the Gen III.
The Generation I trucks generate a whopping 125 hp as OEM. The Gen II Magnum engines crank out 175. So yes I'd say the heads and anything else from a Gen II engine would create some more power. If you gutted the cat and didnt see much increase, the honeycomb materials in there were probably all burned out anyway.
That is all the help I can give. I've never done much inner engine work.
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90 Dak
Dodge Dakota
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4/21/2002
07:09:44
| RE: rebuilding 3.9
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The reason I was thinking of staying with the TBI injection is because no one can tell me exactly how difficult it would be electricly to change over to Gen.II MPI. I have rebuilt many engines in my day and mechanical modifications are no problem for me but when it comes to these new computer controlled engines I am lost. I do like the fuel injection for cold weather starting and other obvious reasons and do not want to go the carb. route. Does any one know if my GEN.I intake will bolt to the magnum heads? Also has any one installed a magnum in a GEN.I? What parts would be need to be changed electricly? I am not interested in a newer truck as this truck is in great shape and I prefer the looks of the GEN.I body style. Again thanks for any help.
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87DakBuilder
Dodge Dakota
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4/21/2002
07:21:32
| RE: rebuilding 3.9
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90 dak, what's up, I'm in the process of doing the same things that you are talking about. I haven't received my Gen II intake manifold yet, but I'm gonna try to bult that up to my Gen I engine. I know that to change from carburation to MPI, I gotta get the computer as well, so for now I'm stuck untill I find a great deal on a Gen II computer. If my plans don't work out, well I'm just gonna find a donor truck (there are a few in Sicily, where I'm at) and gut the entire engine bay. The intake I have is off of a 96 Dak, and I'm getting the Tbi unit as well. Anyhow, as I find the parts that I need, I'll keep you posted. There are a few parts available for us Gen I daks, but most of them are hard to find. Stick with it, and keep me in mind as you find items. Like you I prefer the look of the Gen I Daks to the new ones (hard to believe). If you need any help you can contact me at Nafarious33@yahoo.com
87DakBuilder
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90 Dak
Dodge Dakota
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4/21/2002
11:45:00
| RE: rebuilding 3.9
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Hey 87 Dak Builder! It seems like there are only a few of us Gen.I guys on this forum. Really my 90 Dakota is kind of a Gen.1-1/2. I do have fuel injection but it is not Multi-port like the magnums. My truck has throttle body injection. This looks somewhat like a carb but on top there are two injectors to deliver the fuel. On magnums there are injectors for each cylinder. My engine does have roller tappets. I have done much research but have found little to improve these engines. I have decided to do my own R&D. I have purchased a used 1993 V-6 magnum engine from a local junk yard. I am doing dissassembly on it today and the block is going to the machine shop monday. I am somewhat lucky as a good friend of mine owns this engine shop and we trade work so my cost is minimal. We are planning on boring out the block to 4.0" and stroking the crank to 3.580" to basically have a 270 cubic inch engine or approx. 4.4 litre. This will allow us to use 360 (5.9 litre) pistons and connecting rods. Of course my crank will have to be built up and turned to gain the extra stoke but this engine shop has the ability to do this work. Also the overbore will be dependant upon the wall thickness of the block. If the block is to thin then we will have to sleeve it which really is not that big of deal.Block and oilpan clearances will be checked and modified as needed. I am a metal fabricator so modifying the pan is not a problem. Next we will look at the heads. I would love to keep the multi-port injection but am still not quite sure how much trouble it will be to swap computer, wiring harness,etc. At the very least we will use the magnum heads because they have larger valves than the old Gen.I engines. If we don't use the MPI then I will use my TBI with V-8 ingectors from a 1990 doge ram 5.2 lire. They will fit into my throttle body and give me a little more fuel delivery. Of course heads will be ported and polished along with the throttle body. This along with the headers and gutted cat should allow the engine to breathe much better than stock. We are researching now different camshafts and rocker arm ratios. I know this all seems excessive but I am determined to get this old gal perked up. I like to be different! I will keep you informed on the progress and problems encountered.
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dodgeboy
Dodge Dakota
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4/21/2002
12:01:10
| RE: rebuilding 3.9
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woah...better check that block out before you bore it to a 4'' bore! The magnum motors are considered a thin wall block. Going .030 over on a magnum motor is really the maximum, even at a .030 over bore the walls start to get a little thin. The stock bore is a 3.91 so going to a 4in bore is a.090 over bore...way too much Even sleaving the motor with that much of an over bore may be a problem .. Keeping the magnum heads is a great idea. They are the hot ticket right now for all the hotrodded A engines. The magnum head will out flow most ported A motor heads. They are not a direct bolt on for the pre mag blocks though. I think the cylinders have to be notched. Mopar performance make several pre magnum v6 cam grinds whil for a magnum grind you will have to contact a company such as kammer racving, compcams or hughes engine for a custom grind
good luck
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dsh lawren
Dodge Dakota
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8/03/2003
22:23:04
|  RE: rebuilding 3.9
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Hey fellas, i have a similar interest. I have a 87' Dakota 3.9 v6 (4x4),although I am prepared to swap out my 3.9 for the ole faithful 5.2(318),carb and all.Consequently I am a novice builder and I am wondering upon swapping engines,what should I also plan to swap out?Especially with the 4x4 in thought. Thanks in advance. Des Law
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mezego
Dodge Dakota
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8/03/2003
23:50:49
| RE: rebuilding 3.9
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Good to see there are a few of us pre mag. owners left . i'll also been thinging about pulling the old 6er out and dropping in a new 3.9 or go with an 8 but don't know what i'll be getting into as far as mounting rightin, changing out wire harness . any insides would greatly help
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Joe E.
Dodge Dakota
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8/03/2003
23:54:44
| RE: rebuilding 3.9
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With a 4x4 you have steering box/shaft clearence problems I believe. So you will need to address that. AS well as the tranny. It will not handle a 5.2L when you gas it at all. You can get motor mounts from www.engine-swaps.com . They have an entire kit for $700 or something. You can also get a tranny conversion adapter there too. Makes it a more bolt in swap. Of course the electrical/computer stuff will have to be addressed. Maybe "Painless Wiring" will have something you could use. Good Luck and keep us informed. Later.
Joe E.
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mezego
Dodge Dakota
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8/04/2003
00:00:42
| RE: rebuilding 3.9
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Sorry guys thats a 91 dak I'll got for any info. on a engine change out
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mopar1fan
Dodge Dakota
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4/29/2004
10:36:33
| RE: rebuilding 3.9
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Hey im in the process of building my 89 dakota 360 two wheel drive I also cut 24 inches off the frame and 22 off the box and installed 3/4 ton chevy springs and 59 pontiac tail lights along with a fuel cell and metal coated the bed
It can be a wiring nightmare if you try to use the TBI but i did it with a donor and it wasnt hard at all we tried doing it without it and it was very very difficult but once you get a wiring harness and ecu you can do it no problem
I am an owner of a customs shop in NEPA and we have done a couple of these swaps
I also have a 3.9 block that is bored and rebuilt for sale and a bunch of other dakota stuff for sale i own 3 of these beasts and many of my friends also do so for more info email me at mopar1fan2000@yahoo.com
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Matt
Dodge Dakota
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4/30/2004
15:21:31
| RE: rebuilding 3.9
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It's actually easier then you think. If you have a 5 speed, then I wouldn't worry about the 318 being too strong. The auto tranny poses some problems tho.
If you are going to a magnum 318, then you just need the full engine, pcm and wiring harness. Nearly all the critical sensors would be with the engine, so the PCM matching the engine would work. Only problems I could see are the compatibility with an auto tranny (OBDII PCM's controll shift points) and the speed sensor (it changed somewhere, not sure what year). This is running MPI. So as long as you change EVERYTHING to the new style, then you should be fine.
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