I have a 91 Dakota I just bought with the 5.2 V8 and the truck has a lot of miles on it 240k, at first I was thinking about doing the Magnum on LA block swap with the redrilling but with the miles now I am thinking it makes a lot more sense to just buy a complete used Magnum 5.2, put seals and maybe rings in it and drop it in there instead. Plus I read that if you don't have the magnum piston with the magnum on LA head swap that you don't really get the true magnum performance anyway.

Can anyone tell me if there is a limit on the years of Magnum 5.2's that are going to be a drop strait in swap for this application?

I don't want to convert to a carb, it does not have to be that fast, it's just going to be a nice lowered flat black shop truck but the Magnum makes a good bit more HP than the LA 318.

Or I'm open to other cost effective options for this. I've done lots of engine swaps, supercharger, and turbo stuff before but I don't want this to be a very complicated (or expensive) mission, but I can spend a few bucks on the truck.

Also, does anyone know which Trans this truck has, is it a 42RE or something else? Can a 727 torqueflight drop into this application?

I see 2 possible issues.
1) Somewhere in the early 90s (I believe it was 92 or 93), Dodge changed the motor mounts from the old mounting ears on the block to flat plates with threaded boss in the block. You will need the motor mount brackets for which ever motor your using.
2) I believe the Magnums were all port injected instead of being throttle body like the LAs were. I believe the Magnum was also when Dodge went to the OBD II computer. You may have to upgrade the wiring from OBD I to OBD II. I have no ides what that involves.
I have a 91 Dakota here and its a LA with OBD I and I have a 93 and its a Magnum with OBD II, I'm not sure if the change came in 92 or 93. Gene

If you use the LA intake and distributor is there any reason the OBDI computer wont run the Magnum engine off the factory TBI?

1. Tranny can be anything- 727, 42rh or 46rh. Computer and harness will be designed for 46rh if 4x4, probably 42rh is 2x4.
2. Luckily dodge kept the motor mount ears cast into the block all the way thru 2000 on the 318 and 2003 on the 5.9. Just need the brackets which you should already have on your LA
3. Gotta swap the whole wiring and computer- can't use the TBI stuff. This, exhaust and fuel lines in the toughest part of the swap cause you're dealing with 39 psi now instead of 14.5.
4. OBD II startted in 96. 92-95 parts trucks are your friend- 94-95 computers will run and drive but have an extra circuit which will affect drivability- I'm working on which one it is

Lastly, keep the serpentine drive off the 91!. It was a one year only, 5.2 only, deal and desirable b/c it will bolt to a LA

You will have to do something with the bolt holes in the LA intake manifold that hold it to the heads, the bolts in the heads are in the same location, but at a different angle then they are in the LA heads.

I have to wonder if the port injection is part of the HP bump for the Magnum, though the heads are suppose to be much better. I would think the Magnum would run on the OBDI, might have to use all the LA sensors. Gene

Have you done this swap? You said the hardest part of this swap is the fuel system and exhaust, the magnum MPI uses only 14psi?

What is the easiest solution to fuel system? Does my 91 have a return line? Does the Magnum have a return line? I did a big turbo on an SRT-4 and I got around the no return line situation by mounting a pressure regulator back by the gas tank adding a short return there and it worked fine.

As far as the exhaust, I see that the LA shorty headers are "block hugger" with the collectors in the middle of the header where as the "magnum" headers are laid out more like the stock manifolds with the collectors by the firewall, it seemed to me that the magnum headers would be easier since they are laid out more like the stock LA exhaust system, plus the happen to be CHEAPER. No one makes a simple TRUE dual exhaust for the 91 truck that I can see (at least not for the money I want to spend), everyone uses a single inlet dual outlet muffler to split the exhaust after the converter. I would want to do a TRUE dual exhaust with an H pipe. I am an experience MIG welder so even if I have to fabricate the thing with mandrel bends it's not really a huge problem. Is there anything I'm overlooking about the exhaust? (obviously I assume I need O2 bungs for the OBDII Magnum computer)

Switching to the OBDII computer does not create problems with the 91 transmission?

Does the magnum computer and harness just drop right in? Is things like air conditioning, temp and oil pressure sensors, all that going to be problems? Is there a specific year Magnum donor vehicle that is more desirable than others? Should I be looking to get a magnum engine AND trans to make this easier?

Sorry for all the questions and I appreciate your help.

Magnum engine from 1992-95 are OBD-1 and used a hydraulic 4sp transmission with converter lockup and overdrive toggled on/off with a simple 12v circuit operated by the ECU.

96+ went to a fully electronic transmission and OBD-2 at the same time. For this reason neither the electronics or transmission will swap between 92-95 and 96+.

The BEST thing you could do is swap a 92 dakota engine wiring harness into your 91, and hope and pray the connector at the dash stayed the same. Alternatively you could swap out all the wiring(dash board, lighting, etc) if you wanted to avoid rewiring stuff.

I used a 1995 harness/ecu for my swap, I found the engine wiring harness section is remarkably self-contained once you gut out the lighting, abs, etc. All that's left to hook up is a power, ground and a keyed power. You will need a speed sensor hooked up or you will stall on decel.

The early magnums will want around 35psi of fuel pressure. The TBI's were more like 14 and the 96+ units went to 55 I think. Oblivious to this fact, I first installed a 55psi GM LS-1 fuel pressure regulator/filter because they are easy to retrofit to just about anything. It ran, but rich so I put smaller injectors on to compensate.

The OBD-1 computer doesn't care what transmission you put behind it, so long as its hydraulic. If you put a 3sp behind it, you may get a code for overdrive and lockup circuits open, however it won't affect driveability. I have a stick shift so I found a stick shift ECU for mine so this isn't an issue for me either way. If memory serves, the OBD-1 magnum ecu does have a circuit that tells the ECU if you're in gear or not, however I'm not sure what the function of this is, perhaps to cancel cruise control if you nudge the shifter into neutral?

You will have to transfer over your LA sensors for your dash gauges to work. Also I wouldn't expect the a/c connections to be the same but not sure on that as I don't have a/c in my swap.

Transmission speed sensor
STANDARD MOTOR PRODUCTS SC108
sensor connector
STANDARD MOTOR PRODUCTS SC727

You may, or may not need to change speedometer cable to make it work (depends on what your existing cable is).

nope. as long as you stay with 92/93, it will be plug n play. the gas tank is the same from 91-96, 93-down use the return line, (4 bangers use the exact same pump til 96!) Carter 74654M. 94-up uses a non return system.
use a fuel rail from a 92 or 93 "anything" (full size van, pickup) and a computer from a .'92/93 pickup, van , ramcharger or Dakota with a V8. harness from '92/93 Dakota. there are slight differences in auto vs stick harnesses, like the crank sensor plug is a mirror image between the same truck with an auto vs one with a stick.
I had a 93 that I swaped from auto to stick and used the original computer for the '93/auto trans combo without issue.
Even though 94 and 95 are also OBDI, I experimented with a couple of computers from 94 and 95s and the truck didnt like them. I think they went to a differently calibrated injector when they went returnless in 94.

They still used a speedo cable til (and including) 93, so the speed sensor has a threaded port for the cable as well as a plug for the computer input.
I have had an '89, '90, a 93, 94, and currently have both a 92 and a 96 Dakota and have played with them all extensively except the 96 because I have not had that one yet long enough to be able to, ha ha.

You can tell whether you have a cable or electronic speedo if you know what you are looking at.... the font on the odometer numbers is slightly different between cable driven and electronic driven speedo clusters... having had both (and currently owning one of each) I can see the difference.
yea you can run any trans behind an OBD1 computer and it won't care. If you run a 3 speed auto or a stick, you may get a false code 37 but it won't trip the light. because the computers are programmed to look for the "od engaged" command which a 3 speed auto don't have.... will have no bearing on how it will run.
the other responders to this thread apparently have never messed with doing what you want to do, to one of these trucks..
same things apply to pre 93 vans and pickups too, in fact from the factory they used the same compters respective to engine size and "49 state" vs California" models.

I have never played with a "california equipped" setup so this stuff may not apply to one of those but since Illinois is so far from california, we rarely see those vehicles here.

Great thread, and I'm going to follow along as I am gathering parts to swap a 98 5.9 Magnum into an 88 D100. I have a low mile motor, along with all of the under hood wiring. I need to find a wiring diagram from 98 3500 5.9 Magnum 5 spd truck, so I can try to figure out what I need to make it run. I also need to find out if I need the OBDII port from the same type truck, since I didn't get that. Lots of good info in this thread already!

I figured someone who really knew this swap would show up.

Do you know if Magnum long tube headers will work on a 91 5.2?

I have a 1995 Dakota 5.2 auto 2wd that I want to swap a 1960 Dodge cab onto but want to run the 1995 5.2 EFI and computer in if possible, so I like this thread....... lol

So if you obtain a 92-93 computer, harness, and fuel rail, can you take the magnum donor engine from newer model years with possibly having to harvest some sensor ect from the 92-93? 94+ engines are much more plentiful than 92-93 magnums with reasonable miles...

92-95 magnums are the same. When they went OBD-2 in 96 the sensor connectors all changed but will swap right over. Also the 96+ deleted the intake manifold coolant temp sensor, so that one will need to be drilled/tapped.

I used a 99 engine for my swap and used 95 electronics to run it. Be sure to snag the fuel injectors from whatever donor your harness/ecu comes from.

Sorry for all the questions but how big of a job is the harvesting of a wiring harness out of a vehicle, can you remember what were the biggest challenges of that job? I've done lots of things, rebuilt engines, transmissions, etc, but wiring harnesses I've always tried to stay away from.

What I mean is, without having done one of these, does the engine bay harness have connectors everywhere or are there places that the harness needs to be cut and re-wired into it's new home?

Any tips on what maybe you would do differently today, or tricks? Did you label everything or is it pretty strait forward and obvious?

How did you go about this whole process, did you remove everything like the radiator etc and start with a clean engine bay or did you do it piece by piece replacing the old harness?

I've done many engine swaps but for some reason the minute you add "wiring harness and computer" into the mix I get concerned.

If you use the 92-95 wiring, it's not hard. 96+ when they went OBD-2 is a rats nest, stay away from that one if you're not comfortable with wiring.

I grabbed a 95 harness from a jeep grand cherokee at the junkyard. Start at the engine computer and work your way out from there. The wires go directly from the engine computer to the sensors. Unbolt all your grounds. If memory serves, I disconnected the engine harness at the firewall. The only wires I cut during removal were for the oxygen sensor and speed sensor because the donor vehicle was on the ground with no tires and I couldn't get under it. I had to wire those up after the fact which sucked but at least it was only two sensors. Once you get the harness home you gut out the stuff for the donor vehicle's lighting, horn, starter circuit, windshield wipers, etc. Keep the alternator wires as the EFI computer has voltage regulator built in. You will find the engine control section is pretty self-contained making this part easy. I think the only connector in the whole thing is the one for the fuel injectors. After that it's just putting power, ground and keyed power to the harness to make it run. I installed some fuses too just in case. Also there's a switched ground wire that comes from the ECU to flash back engine codes so you'll want to wire that one up.

I used masking tape and a pen to label what sensor each connector is for. The charcoal cannister purge circuit I removed completely. I kept the cruise control wiring in place but haven't tried hooking it up yet.

To install, I installed my new engine and transmission. Hooked up by rad, exhaust and got all my mechanical work done. Then I took my old wiring harness, gutted out everything except the lighting, windshield wiper, starter and horn circuits and reinstalled it to make sure all that stuff still worked. Then I laid my (now gutted) EFI harness over top and ran the wiring to the sensors, figured out the wire routing and temporary taped the wiring all in place. Then I wired in my fuse holders, ran wires to my constant/keyed 12v sources. After I taped and zip tied everything into it's temporary spots I went to crank. Then key on/off/on/off/on to check codes with the flashing check engine light. Everything looked as expected so hit the key and see what happens. Mine would fire for a second, then die. Eventually I figured out the jeep ecu has security built in. I got an ECU from a Ram, problem solved. Hit the key and she fired right up and purred like a kitten. Then go back, do a final clean up, wrap all the wires together, mount ECU permanently, hang wiring harness on firewall clips, etc.

Yup. another swap I had to do over the years was a 318 Mag from a 94 Dakota into a 97 Ram 1500. I swapped the intake from the 97 with all of its original sensors onto the 94 longblock and it was plug n play. the long block is essentially the same from 92-03. I think 92-93 might have had a slightly warmer cam, but not enough to throw off the computer in any of those years.
some of the other answers in this post are interesting as I have a 80 Volare and a couple of 90s 318s with harness and all, and am looking to cut down a harness to retrofit, that's something I have yet to do, I have one harness from a 92 Dakota and (I think I still have) one from a 97 full size pickup..... I will probably stay with the 92 setup with its OBD1 system as it is slightly less "involved" though they say the OBD II of the '96+ era is more likely to be tuneable, but thats OK because even a stock 318 Mag puts out 2-1/2X the original 90 "rated" HP of the original lazy 6 and that car ran surprisingly well with that motor in place.... not looking to get crazy here/

Yeah the OBD-1 stuff is not tunable whatsoever. The only tune mod I'm aware of is a mopar performance ECU that was offered. In my case, I was replacing a 100hp, bagged out AMC inline 6 in my jeep wrangler so even a stock 5.2 is over double the power.

Do any of you guys know if the OBD2 ECU has to see the Can-bus/gauges to work? If so, is there a fix to not use it? I want to run manual gauges in my old truck, with the sensors the ECU needs to see plumbed in also. I apologize to the OP for the hijack but lots of good info is coming out in this thread.

The www.hotwireauto.com web site has a vary detailed listing of bus-bar /gauges that work, and won't work together. If you understand all that stuff, it is probably great info!
Gene

So I have a chance to buy a 2001 5.2 with 27k miles on it that was in a fire and melted all the electronic connectors. If I bought that motor could I not just swap the sensors, distributor and the TBI (with drilling the magnum heads for LA intake) and have the current system run the engine?

What would be the absolutely easiest thing to do to make that engine work in a 91 dakota?

So I have a chance to buy a 2001 5.2 with 27k miles on it that was in a fire and melted all the electronic connectors. If I bought that motor could I not just swap the sensors, distributor and the TBI (with drilling the magnum heads for LA intake) and have the current system run the engine?

What would be the absolutely easiest thing to do to make that engine work in a 91 dakota?


BUMP

I believe you can just swap over the stuff from the 91 motor onto the Magnum 5.2 and it should run. The intake will be the biggest problem. Gene

What about the engine mounts? I've heard a lot of conflicting stuff about it.

jerseybud nailed it. Our '93 Ramcharger has a '97 318 replacing the original, no mount modification required. The later mounts are just along for the ride.

Robert

Yes, you could.

I have a 5.2 sitting at my house if you want to pull the intake and what wiring is left on it the motor was pulled from a 94 jeep just pm me you can have it i was saving it for a spare for my truck. I live in south stafford

Well, I got a 2001 5.2 from a Dakota with 27k miles on it. I'm hoping I can just swap everything over from the LA 318 onto it and be rolling.

I appreciate that, if something comes up I will def take you up on that. Right now I think I have everything I need to do the job.

My worries are motor mount issues (since this engine is a 2001) Someone said "up to 2000" they kept the block casting the same as far a motor mounts. Hopefully that isn't going to be an issue.

I'm going to try to make an adapter for the LA intake bolts so I don't have to re-drill the magnum heads. I've read you can drill the intake manifold and make an angled spacer to let the bolts run strait down.

One other thing I wondered if it's possible to just swap the TBI assembly onto the magnum intake... I haven't looked at it that closely but I just wonder if there is some way to make an adapter or something to just use the Keg intake with the 91 TBI.... Obviously you would have to block off the injector holes.

What trans am I looking for if I decide to do the transmission? 42RH? The engine I'm using is a 2001 Magnum 5.2 but I'm running it off the 91 TBI computer and TBI...

So I could use any v8 trans from like 89-95 when things stayed OBDI?

I would like to keep a trans with overdrive and a lockup converter if possible for gas mileage.

You'll be looking for a 95 or older 42RH or 46RH.

You don't want to put the TBI on the magnum intake. The magnum intake is designed for dry flow only and putting a TBI on top will give you an engine that runs like a bag of crap. You could put a propane mixer on there, because it's a gaseous fuel.

I have a 2001 5.9 and it still has the old style mounts on the block. It also has the newer style mounts on the block.

This is a 5.2. Hopefully it does not matter.

Is there anything I should keep from the Magnum setup? What sensor feedbacks does the TBI setup work off of? RPM, Coolant Temp, IAT, TPS?

What about aftermarket intakes? Any real benefit to putting something like the AirGap on there and fitting the TBI to it? Does an adapter to do this exist?

What trans is in there now? The 42rh or 46rh?

I think your dakota would have the 42RH.



I haven't tried it so I couldn't say. I would think you would still be flow limited by the TBI throttle body but I don't know what that flow is.

Is there any reason I cannot leave the Magnum flex plate on there instead of switching to the LA plate? I want to leave the crack position sensor in place in case I decide to get rid of the TBI setup and convert to MPI.

You can leave the Magnum flex plate, and depending on what transmission you're using....you may have to oval out one bolt hole where the torque converter bolts up. I think this is the case of you are using a 904 or 727. A 5.2 flex plate will not have weights welded to it, and a 5.9 flex plate will. The weights for Magnum 5.9's are on the flex plate instead of the converter like LA 360's. You use a neutral balance converter with either a 5.2 or 5.9 Magnum.

AHEM. No, switching the LA intake onto the magnum engine is not really a do-able situation. The LA intake sits much deeper in the valley and even by "hogging out' the bold holes to make it work it would be highly UNLIKELY that you would be matching the ports to the magnum head. It would be a really hack job install.

I have resigned myself to ordering a air gap (knock off) intake and I'm going to try to fabricate an adapter to use my existing TBI throttle body onto it. It looks pretty strait forward and I have some 1/2 flat aluminum laying around.

I'll let you guys know how it goes... I'm really trying to keep the TBI but if it's not possible, what do I have to get a generic vaccume advance distributor off ebay ($45)?

BTW- Is the magnum water pump pulley just "pressed" on? I used a puller to get it off and now I guess I'm realizing I should have just left it. I'm a bit nervous about leaving it just "pressed on", I assume I'm not missing something?

The TBI will not supply enough fuel for the magnum engine, it will run very lean as you push the accelerator. There is not enough flexibility in the programing to do that safely. If you insist on doing it wrong than at least get a 5.9 computer and throttle body from a full size truck, it will be closer to correct but still not right.

The knock off manifold is just as much a "hack job" as modifying and bolting on an LA intake, they are junk. The one I had would rock around in between the heads on a squaredecked block, it needed squared up it self, it was cheaper to buy the eddy and bolt it on than it was to buy and correct the knock off.

I have put LA performer intakes on magnum motors and the port was alighned decently as it was a smaller port dumping into a bigger port and with a thermoquad it ran awesome. It is also very easy to open up the ports a hair for even better alighnment.

Guys used to adapt LA intakes to magnums all the time. Years ago there used to be a jig floating around to redrill the magnum heads to accept the LA intake bolts.

Something like this...

No, I mean NOT redrilling the Magnum heads but "hogging out" the bolt holes of the intake to work. Some other forums claim that can be done. I might be possible, but it isn't very good. Apparently there was a hotrod magazine build that did this instead of drilling the heads.

The other issue I have run into is the Magnum oil pan does not work in the 91 Dakota body style. It hits the crossmember and the oil drain plug would be "in" the crossmember even if it didn't. So, that is another major hiccup I have hit. I'm just swapping the oil pans and oil pump pickups "at least I'm trying" but I'm not even sure that is going to work with finding the right oil pan gasket to use. The magnum gasket does not seem to work (my dad went to the parts store with the LA oilpan and that is what he is saying) I wasn't there so I can't be sure about that.

Just curious what facts you rely on to say that the TBI setup cannot supply enough fuel for the magnum engine. Have you tried this or are you just speculating?

I don't know, I see people posting up totally ridiculous things like putting 750cfm double pumper carbs on 318 engines and say how much power they are making so....

I suppose it could run lean somewhere, I guess I'll real time the fuel trims and see if the computer is trying to compensate. I'm used to dealing with mass air and speed density setups from much newer vehicles so I'll have to look into how this TBI setup works. Maybe I can add some fuel pressure or something with a piggyback, I think I have an emanage laying around somewhere.

I do have a 650cfm 4 barrel carb I could put on there if the TBI does not work but to me that is still too big of a carb for a 318cid engine. I really hate to put a carb on there, I'm not building a race car, it's just a low rider with a V8 for a go getter for my business.

I put the "hack" intake on, and it fit perfectly so I don't know, maybe you got a [censored] casting or maybe your machine shop did what they always do and say "its not them, its you" because I have yet to meet a machinist that has ever jacked up an engine.

I just sold my 96 reg cab short bed dakota with a 5.2 with a 5 speed and am regretting it last i heard it was being lowered too . i would rather have MPI than a TBI

All 93 (maybe 92 as well, but 91 is definitely TBI) and newer Dakota V6 or V8 is MPI. Some guys here say the wiring up to 95 works so, I suppose you simply need the MPI intake and some injectors, maybe you can just keep your 96 intake.

At this point, I'm not sure who to believe, I think if it was my project I'd just bolt something together and see what happens.

When I do my 47 Dodge, I'm putting a 97 5.9 magnum with its original trans, and a Hot Wire harness. I know that works, and the stuff is here. Gene

I don't think part throttle will give too much trouble, it'll be full throttle where the computer can't monitor or adjust. However with what you're doing, I'd be it will be close enough to not pose a problem because you'll probably only be making 200hp.

Magnum oil pans use a reusable rubber gasket. The LA pans use cork gaskets.

That's all great guys. Have any of you actually PUT a magnum 5.2 into a 91 dakota? Because it does not fit. The oil pan slams right into the cross member. I know because I was trying to do it two days ago.

I can say it's a pretty major thing to leave out when you are telling people that you can do this swap.

And the LA oil pan absolutely does NOT interchange to the magnum engine. I know because literally just walked inside from the garage trying to do it. The rear pan seal is an entirely different diameter than the LA pan.. So I'm pretty much completely screwed right now.

I don't know what engines these people are working on that you can interchange these oil pans.

The only possible thing I can see that could be done is swapping the LA rear main cap an convert the Magnum engine to the older LA style rear main seal which I just don't know if that is such a great idea. There is a pin set in the magnum journal that isn't there on the LA engine so I would have to remove it, or drill a hole in the LA main cap to make it work and all that seems very iffy to me.

Just know that the stuff you post up on the internet when you are not 100% positive about it can cause other people a TON of work and lost money.

Parts book is listing a 1991 5.2 Dakota oil pan as part # 53009878

Lists 92-93 oil pan for Dakota as 53020287

What application oil pan are you using now?
A magnum engine requires a magnum oil pan

rockauto shows pic of 92 dakota oil pan (56 bucks!)- it has a thin sump compared to a full size pickup. Where is yours interfering? Should be a simple think to fix with no welding or cutting

If you're needing to run an LA pan on a Magnum motor, the LA pan must be from a 360. It doesn't matter if it's a 5.2 or 5.9, they both have the same size rear main cap and seal as an LA 360. That's how people put Magnum motors in cars.....use an LA 360 car pan. I have no clue as to whether an LA 360 truck pan will fit an early Dakota chassis.

I have done this exact swap, in a 91 no less, any 92 or later dakota or durango 5.2 or 5.9 oil pan will work just fine. Some of the late vans after about 2000 used the skinny rear sump, rams earlier vans and jeeps used the one that wants to sit on the frame and steering... If you use that pan you can use the good one piece magnum gasket. Do not swap the rear main cap, it wil eat up your engine quickly unless you line bore and hone the block. You will also need the oil pick up tube.

The TBI ran great on the original 318 but would not run right on the magnum, Idle was about the only good thing it did. This was with the eddy intake and adapter on and big single exhaust and the 92 93 ex manifolds. I think the 318 TBI engine had 180 HP and the magnum was 235 so it just is not right. We eventually swapped in a 93 intake/harness/computer/fuel pimp and it ran awesome and yes there were a few wires to swap but no biggie.

I have done this swap and am telling you the way to do it with as little headache as possible.

The eddy intake bolted on with no issues whatsoever, hopefully the knock off you got is better, check the port line up also as it was way small on the cheap intake.

A carb swap with the correct intake is a breeze also and you can use the TBI fuel pump and return system with a cheap regulator and a 650 is no where near too big for this motor. Again I have done exactly that. I have done quite a few very similar swaps to this but I gues I should stay off your post. Sorry I tried to help.

Interesting, I would have thought it would have been close enough to run and drive ok, even if it wouldn't have made best power. I wonder if it would have done any better with a more restrictive stock TBI intake manifold?

I would run a 600-650 cfm carb on a 318 no worries. I'm not a fan of TBI at all but to each their own.
Good info on MoParts, not always perfect but nothing really is?