87 dakota 3.9L La to 318 La swap - DodgeForum.com


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87 dakota 3.9L La to 318 La swap

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  #1  
Old 04-19-2017, 10:20 PM
new_red87
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Default 87 dakota 3.9L La to 318 La swap

So been searching the internet for information, but you know how search results can go! Have not found much information in the way of my year Dakota. You find a lot more info on the 2nd gens. My truck is an 87 Dodge Dakota LE 4x4 Long bed. Right now it has a 3.9L v6 in it that is worn out. Just bought a 318 out of an 86 or 87 ram truck.

Now what i need to know is has anyone on here done the swap? what kind of electric fan setup did you use? and do i need to swap out the transmission i think i have a 3sp 904 trans or can i beef up the one i have in it?

Also will I have to do any other modifications to make engine fit like maybe change out transfer case or other parts? I know it has been done before they started doing it in 1988 but those were magnum engines i believe. engine I got is La motor came with all the accessories, looked like top of motor had all new performance parts like an Edbrock 4bbl carb and new manifold, all chrome valve covers, new distributor and plugs and wires etc.

Last edited by new_red87; 04-19-2017 at 10:45 PM.
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Old 04-19-2017, 11:09 PM
RalphP
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Heh.

1) You'll need motor mounts; the 86 or 87 318 will still be "elephant ears" while the 3.9 will be using what's also known as "Magnum" mounts.

2) No, the Magnums weren't used until 1992 model year; for 1989, Carroll Shelby's company grafted 318 LA motors in (that also had the Magnum mounts!) but there was a lot of other items to make it fit. When Dodge started with the 1991 Model Year putting a 318 LA in, they also bubbled out the front. (There's a thread here on making that fit.)

3) The 999/998 3 speeds will do a 318, but they won't be as durable as, say, a 604 or 727 would be. Or, if you change, I'd swap to a 4 speed and pick up overdrive (what would be known as a 518 or a 44RH/46RH).

But, being a 4x4, the problem gets to be a bit more "fun". I'd HIGHLY recommend selling the 87 and picking up a 5.2 based truck instead.

4) Don't forget you get to rewire the dash. Good news, the 1987 uses the ESC (Electronic Spark Control) with a feedback carburator, so there's not a lot of ECU to bypass or replace.

But for the info, yes, there's actually a thread where two people have dropped 318s / 5.2s into their early Gen1 trucks.

RwP
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Old 04-19-2017, 11:31 PM
new_red87
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Default re: swap info

Quote:
Originally Posted by RalphP View Post
Heh.

1) You'll need motor mounts; the 86 or 87 318 will still be "elephant ears" while the 3.9 will be using what's also known as "Magnum" mounts.

2) No, the Magnums weren't used until 1992 model year; for 1989, Carroll Shelby's company grafted 318 LA motors in (that also had the Magnum mounts!) but there was a lot of other items to make it fit. When Dodge started with the 1991 Model Year putting a 318 LA in, they also bubbled out the front. (There's a thread here on making that fit.)

3) The 999/998 3 speeds will do a 318, but they won't be as durable as, say, a 604 or 727 would be. Or, if you change, I'd swap to a 4 speed and pick up overdrive (what would be known as a 518 or a 44RH/46RH).

But, being a 4x4, the problem gets to be a bit more "fun". I'd HIGHLY recommend selling the 87 and picking up a 5.2 based truck instead.

4) Don't forget you get to rewire the dash. Good news, the 1987 uses the ESC (Electronic Spark Control) with a feedback carburator, so there's not a lot of ECU to bypass or replace.

But for the info, yes, there's actually a thread where two people have dropped 318s / 5.2s into their early Gen1 trucks.

RwP
wow! i think the motor came with some mounts attached to it. so might have the mounts I need. As far as the wiring goes im taking it to a buddys shop to do. only fear is he has never done the swap before. I was hoping wouldnt be to much of a pain of a swap. Way truck sits right now thought it would be easier to fix and do the swap. Idk if you know how hard it is to find a 3.9L v6 for that year 87 being only year carbed but it is almost to near impossible outside of buying a crate motor which is way too expensive and as for the first gen rams those are becoming harder to come by also!
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Old 04-20-2017, 01:21 AM
RalphP
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Quote:
Originally Posted by new_red87 View Post
wow! i think the motor came with some mounts attached to it. so might have the mounts I need. As far as the wiring goes im taking it to a buddys shop to do. only fear is he has never done the swap before. I was hoping wouldnt be to much of a pain of a swap. Way truck sits right now thought it would be easier to fix and do the swap. Idk if you know how hard it is to find a 3.9L v6 for that year 87 being only year carbed but it is almost to near impossible outside of buying a crate motor which is way too expensive and as for the first gen rams those are becoming harder to come by also!
Oh, the 318 will have motor mounts.

They just don't point to the frame on the Dakota ...

For instance, read up at Schumacher ( http://www.engine-swaps.com/Pages/Pr....96Dakota.html ) for the motor mounts they offer.

Also, look at http://www.magnumswap.com/using-la-parts-on-a-magnum/ specifically the "motor mounts" part. That 318 from the Ram won't have the same bosses on the MOTOR; its still got the older "elephant ears" mounts, instead of the newer mid-engine bosses (aka "Magnum Mounts".

As to the rest of it - the BLOCK can be the same for the 87 as for my 88, for instance. The cam will be a bit different but not radically. The intake and carb will be different; can't you reuse those off your old block?

The old one can also be rebuilt if necessary. It's what I'm planning on my 358,000 mile 3.9 in my 1988 ... it's served long and hard, but it's just plain wore out by now.

Again, read the threads here ... Robertmee's threads (specifically, for you, https://dodgeforum.com/forum/1st-gen...-solution.html ); where he talks about grafting the 5.2 into his 1990 https://dodgeforum.com/forum/1st-gen...ne-swap-4.html ); Ragged89's 'vert build which covers some of the same problems. Neither one had to fight the motor mounts; again, lay a GOOD eyeball on that 318 and notice where the motor mounts up, then examine the 3.9 and see where the motor mounts THERE.

Oh, you have one more problem with it being a 4x4; the motor mounts (frame side) changed with 1991, and I'm not sure how the 4x4 motor mounts will be affected.

RwP
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Old 04-20-2017, 08:33 AM
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robertmee
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If you search my username, I have several threads that will help, but the one Ralph linked is most helpful on the biggest issue you face. A 318/360 LA will not clear your radiator because of the long water pump snout. I actually put in a Magnum, but kept the LA water pump because my crate engine was carb'd and I prefer the V-belt look, so from a space requirement, it was the same as putting in an LA block.

Shelby solved the problem with its build by shoving the engine back against the firewall which means new motor mounts and driveshaft, and possibly tunnel work to make the bell of the transmission fit. I solved the issue by swapping a post-91 front end onto my truck. After 91, when Dodge started offering 5.2L options, they redesigned the radiator support and nose of the truck to give the extra room needed. The fenders stay the same, but to do the swap you need from a 91-96, a radiator core, hood, headlights, front bumper and bumper valence. You also need to move the radiator core support holes in the frame forward 3" (this is what gives you the extra room for the LA motor and puts the mounting holes in the right spot for the fenders). https://dodgeforum.com/forum/1st-gen...ert-build.html

The other option is to put a magnum 5.2 motor in there. The magnum with the serpentine belt setup uses a shorter water pump and it will just clear the radiator as is.

As for your other questions:

I have the overdrive version of the 904 (A500) in my setup. I did rebuild it with Ray Asbestos Clutches and Red Kolene Steels and other heavy duty parts to stand up to the 360 Magnum.

For electrical I mapped out everything and completely redid my wiring harness and removed the ECU (I went carb'd). I have a thread on that too and everything that can be removed, and what you need to add to eliminate the ECU. In general, the ECU in my 90 TBI controlled the fuel, spark, AC, transmission, cruise and emissions. I removed the AC to make room for the 360 plus mine is a drop top (don't need no AC). I went Carb'd, so all the fuel management went away...I kept the fuel tank electric pump and used it for the Carb. The Spark is easy...use an HEI GM style distributor. The transmission if you have OD and Lockup needs pressure switches and a vacuum switch to control. TCI makes a kit for that. I eliminated cruise. For Evap, I used a vacuum PCV setup and a vacuum switch to control the purge line to the evap canister as the fuel tank needs venting. https://dodgeforum.com/forum/1st-gen...onversion.html

Bottom line, it was a fun project for me, but if you're looking for a quick inexpensive swap, it's not going to be one. You're better off finding a junker 3.9L and rebuilding the engine.

Last edited by robertmee; 04-20-2017 at 09:01 AM.
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Old 04-20-2017, 09:09 AM
93 ragtop
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I have not taken the time to read everyone's response to this post, but I will tell you what I have found. BTW I plan to do the same to mine, only mine is a 5spd.

First off, 4wd use a different mount then 2wd.

Sell the 86 motor and find a complete magnum. Install a carb intake ie. edelbrock airgap. and a hei dist. of your choice.

The main reason to use the magnum is the serpentine belt system. It is shorter, and will just clear the radiator. With it, you can use your existing V6 motor mounts.

I strongly suggest that you look up members ragged89 and robertmee. There is a lot of information they have posted about this swap.

For fans, if you delete the AC look at what ragged89 did. He mounted an intrepid fan in front of the radiator.
If you want to keep ac, (I do) look under my post and I have one showing the shelby fan setup. They sandwiched the fans between the radiator and condenser. I believe this will not be too hard to duplicate with some of the slimline fans on the market.

I will try to post more latter, but have to get to work now!!

Edit to add, mine is a 87 and I dont believe there is any dash wiring needed. Speedometer is mechanical, no tach that year, water temp and oil pressure should move from your v6 to the v8 engine. Not sure if Im missing something or not.

Last edited by 93 ragtop; 04-20-2017 at 09:12 AM.
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