I own a 1989 Dodge Dakota Sport Convertible 4x4 with auto transmission with no A/C. I currently have more than 150k miles on her and I get about 16 miles per gallon. My question is; Does a 5.2 / 318 engine swap out with the 3.9V6? Are there any modifications needed that I should be aware of? Will all the parts bolt on? Is there much power difference? Is the gas mileage better or worse?
Thanks guys for any info.

 

 

You'll need electric fan(s). Everything else will swap in. Itd be advised to switch transmissions too. It'll swap right in. You'll want a carb fed magnum unles you want to do a lot of wiring. And if you're going to do it, get a 5.9 360. No reason not too. Mileage may or may not change. Depends on condition of your engine, the new engine and your driving habits. Could go up, could stay the same, could go down. Hard to tell. Too many variables.

 

Like Toby suggested I swapped a carbed magnum into my 90 vert. There are several considerarions:

You will need a serpentine water pump set up on a magnum. I went with an LA style water pump and had to swap the front end with a 94 to fit inside the radiator. A serpentine setup has a shorter pump snout and it will just fit inside the radiator. But you'll need electric pusher fans as Toby noted.

Your 89 has a 42rh transmission. It will not last behind a v8. Be prepared to swap to a 46rh trnasmission.

If you go with a 360 be aware that the 318 and v6 are internally balanced engines while the 360 is externally balanced. That means either a flex plate change with weights and a neutral balanced converter or a custom converter with weights and a neutral flex plate.

I'd you search my ID I have a long build thread and several smaller threads dealing with various issues on this swap. It was quite the learning process but I could do it in my sleep now. The devil is in the small details.

 

There are 2 members on here, who I would research and read their threads. They have actually done the conversion you are talking about and have detailed it for the rest of us.
They are robertmee and ragged89.
Just a hint. Putting a V-8 in a 87-90 is completely different then putting a V8 in a 91 up. The 91 is basically a simple swap..... The 91 and up was designed for a V8.
The 87-90 was not.....
And yes, Shelby put a V8 in a early dakota, but again, the truck was not designed for it. It required fans in front of the radiator, and he used a custom crossmember for the motor....
Also, keep in mind 4wd and 2wd dakota's are different trucks, different motor mounts, different steering systems, etc.

The two members above I referenced, both have conv. trucks, but they are different.
Listed below are some of the details and differences in the trucks along with a few links to get you started.

Robertmee, has a 2wd, automatic, 5.9 magnum converted to a carburetor, and using a V-belt accessory system.
Here are a few links to his build.
https://dodgeforum.com/forum/1st-gen...gine-swap.html
https://dodgeforum.com/forum/1st-gen...estions-4.html

Ragged89 has a 4wd, 5spd. 5.2 magnum with factory EFI
Here is a link to his build.
https://dodgeforum.com/forum/1st-gen...le-dakota.html


FWIW I have a 87 4wd 5spd truck. I plan to put a stock, (for now) 5.9 carbed magnum, with a serpentine belt system. It will kinda be a combination of the 2 above trucks.
I have already upgraded the transmission from a NV2500 to a NV3500, have added a external electric fuel pump, (87 was mechanical) and have swapped rearends.
My next steps are to set up a underhood fuse and relay panel for the fans, fuel pump, etc. and of course the fans.
I want to keep AC and neither of them have.... so that will be differernt.

Two important things that you need to consider before starting this conversion
1. Do you have other transportation, and are you prepared for the truck to be down for awhile?
2. Do you have emissions requirements?


Good luck!! and BTW, welcome to the forum!!

 

Thank you everyone for such a quick response. You have given me a lot to think about. I plan to replace the engine with a crate so I just have to decide which one.

Thanks again

 

I have a 88 dakota had 3.9 i swapped in a 318 from a 97 ram 1500 evry thing was bolt in, i kept the fuel injected heads put a high rise 4 bbl intake from jegs put on a holley carb and a stand alone ignition and distributor also from jegs used the original dakota tank and fuel pump just did a double regulated bypass (regulated the carb and spliced in a regulated return for excess fuel) wich helps the fuel from heating from the pressure. Recently re wired the entire truck front to rear with a universal painless kit. Couldn't be hapier seems to be a horsepower gain fuel econ loss but way more fun

 

Very Nice!!! I did a 360 swap into mine and have a very similar fuel delivery and ignition setup...has worked like a charm.

Did you end up using the Ram ecu or go computer less?

 

i went computerless just a stand alone ignition. i wanted to keep everything as basic as i could. just kept the magnum heads for the higher compression.
how did you do the cooling i have an electric fan mounted on face of radiator. No room for fan on motor. Seems to be keeping up but havent had a chance to run it for long distance in the heat yet.
i am also looking into doing the solid swap in the front just not sure how long that 7.25 ifs will hold up

 

You can search my username and find my build thread...mine is a 90 vert. Mine is a bit unique from yours...I went with a magnum block and heads...380hp crate. But it was a carb setup with the LA style water pump and v belts which has a much longer water pump snout. So to fit the engine inside the radiator I swapped in a 94 front nose. This gave me enough room to run a flex fan clutch less on the crank. I still installed the wide HD towing radiator and put a 3000 cfm pusher electric fan on front of the radiator. Being a vert I removed the AC and condenser to make room for the pusher fan. I haven't needed a shroud and it stays well cool.

I also went computer less. I thought about the painless route but didn't want to rewire the cab. So I used the OEM harness....completely disassembled it and pulled about sixty wires out I didn't need. I repurposed the AC relay as an Overdrive relay that's driven by the interior OD switch. Wired that into a PAC vacuum and pressure switch setup for the trans. Used a converter for the distributor tach signal to my factory rpm gauge. I even kept the charcoal purge system for the fumes using another vacuum switch, purging on WOT.
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