I know most everyone will tell me why not do a V-8? Valid question, one reason is I only bought this Scamp because it is different! I'm a GM man normally, but this Scamp just caught my eye, so I bought it. I have been debating (mostly with myself) on what swap I want to do. Right now it has a 225 slant six and it's tired and ready for a rest! I found a decent buy on a 3.9 Magnum, close to my home that was running and driving when the guy shelled his trans. Any thoughts would help me out here, I have never done this kind of thing before and want to be able in the end to say "I did this!" I have an automatic trans, but don't know how to tell if it's a 904 or 727? Thanks for letting me join your group and GO MOPAR!! Lol....by the way, my wife and I just purchased a 2020 V-6 Charger! Love it.
Putting a 3.9 Magnum in my 1973 Scamp
- Thread starter Kenjenok
- Start date
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Ben Drinkin
Hey bartender!
904 is a square pan. 727 has an 'ear' on the right front. Obvious when you see it. And Welcome to the fun..
Welcome!!!! Neat project!!! If you were a GM man, I highly recommend the 3.9 V6 till you get used to the power... 
Projectile Dart
Well-Known Member
Ive seen another member here swap a 3.9 into an A body before, its been done before and completely possible. My brother had a 2001 Dodge Dakota with the 3.9 v6 and that truck was dead reliable. Only issue it ever had was breaking the original tensioner at 90ish thousand miles, then breaking aftermarket tensioners about every 15K after that. It pulled really hard, and had a great sound. Should be fun if you really want to avoid going v8 or building a slant
67Dart273
Well-Known Member
Seems to me someone wanted to do this swap. Seems to me the engine mounts would be a complete fabrication. I think you will need to fabricate a front sump pan. Depending on what you do for a transmission, I believe you will want the original V6 flex plate---which is weighted to balance the engine---against a so called neutral balance converter. Older converters are not drilled the same, you will have to elongate one hole in the flex plate
I have no idea what you need to do for exhaust, you may have to fabricate headers or maybe even turn headers around backwards. You will need a fan shroud about 75 ft long LOL
I have no idea what you need to do for exhaust, you may have to fabricate headers or maybe even turn headers around backwards. You will need a fan shroud about 75 ft long LOL
Keep us posted as it goes! It's a shame that the MP/DC 3.9 parts were made in such small numbers. One small power upgrade is if you could find a production 3.9 LA cam to swap in, they provide a little more lift and .050 duration with the 1.6 rockers.
dano
Evil Handy Man
Reading some 3.9 to 5.2 (or 5.9) swap threads in the Dakota forums the mounts are the same (I always thought a 3.8 was a 5.2 with 2 less cylinders?). But there is an issue with getting LA/Magnum to slant 6 mounts swap kits so that might halt your swap in a hurry. You could put an wanted add up for a 73-up V8 k-frame. For all the BS, I'd just do a 5.2 swap to rebuild the slant and throw a turbo at it.
You're going to need a V8 transmission as the slant six transmission does not have the same bellhousing pattern. A 318 would be much easier. Easiest yet, would be to refresh the slant six. 3.7L to 3.9L is not "much" of an upgrade.
@Kenjenok
In Garrett’s post below... I want to clarify something you might not be aware of.
1; The Magnum already has 1.6 rockers vs the older LA 1.5 rockers.
2; I would not go back to a LA cam since most are older Hyd flat tappet (HFT) and the later (newer) models just before the Magnum were Hyd roller. I do not know if there is a difference in specs, but a new cam would be better. Look into Comp Cams or Lunati cams since they have a few for the Magnum V6 with the smaller ones not needing a computer retune.
Going backwards to a HFT will also need new tappets and hollow pushrods since the Magnum oils the valve train through the pushrods and the LA doesn’t.
Most Magnums (all that I have crossed) have the LA engine mounting bosses. You’ll need a /6 to LA V8 swap kit. Look to Trans Dapt @ Summit racing .com. Schumacher Creative Services may no longer have the proper swap mounts anymore.
Try and get the OD trans that is the Hyd model, not the electronic model for shifting purposes. The 42RH.
Do a thread search on this topic of a Magnum V6 into a car. It’s here somewhere. It was a really good thread and a very well done job I might add!
Does anybody have that thread saved or bookmarked?
In Garrett’s post below... I want to clarify something you might not be aware of.
1; The Magnum already has 1.6 rockers vs the older LA 1.5 rockers.
2; I would not go back to a LA cam since most are older Hyd flat tappet (HFT) and the later (newer) models just before the Magnum were Hyd roller. I do not know if there is a difference in specs, but a new cam would be better. Look into Comp Cams or Lunati cams since they have a few for the Magnum V6 with the smaller ones not needing a computer retune.
Going backwards to a HFT will also need new tappets and hollow pushrods since the Magnum oils the valve train through the pushrods and the LA doesn’t.
Most Magnums (all that I have crossed) have the LA engine mounting bosses. You’ll need a /6 to LA V8 swap kit. Look to Trans Dapt @ Summit racing .com. Schumacher Creative Services may no longer have the proper swap mounts anymore.
Try and get the OD trans that is the Hyd model, not the electronic model for shifting purposes. The 42RH.
Do a thread search on this topic of a Magnum V6 into a car. It’s here somewhere. It was a really good thread and a very well done job I might add!
Does anybody have that thread saved or bookmarked?
thesiren74
Well-Known Member
I'd just rebuild the slant and put a torque storm on it.
Professor Fate
Push the button, Max...
There was a build thread a few years back of a member who V6ed his early Dart wagon, can't find it right now; but if it fit into an early A, your Scamp should be no problem.
Decisions and hurdles to overcome:
Oil pan- the V6 oil pans, to my knowledge, were all rear sump. That puts the sump right where the steering linkage is. Some fabrication on the pan and pickup will be necessary.
Engine mounts- more fabrication, nobody makes swap mounts for the V6. Magnum V8s had the LA style mounts in addition to the mid-motor Magnum mounts, the 6s I believe don't.
Exhaust- the manifolds should work, people have been running the V8 Magnum manifolds with a little judicious grinding and engine shimming. The big drawback is that it was manual steering only- won't clear the power box. Now with the V6 being shorter in length, you just might get away with it with power steering. Pure conjecture on that.
Headers are a no-go, nobody makes them for your application, and you can't just mod the V8 headers by lopping off one header tube on each side even though the 6 is basically an 8 with 2 cylinders deleted- they omitted the 2 rear cylinders, (edit- rear on driver's side, front on pass. side) so that would move the entire header rearward by a substantial amount, giving you all kinds of clearance issues. I suppose you could make your own, though...
Electronics- I assume you'll be running the factory EFI (rotsa ruck finding one of the old DC 4bbl manifolds and/or electronic distributors), so start reading up on the computer/wiring requirements for Magnum EFI in the "Magnum Swaps" forum- the wiring and fuel requirements are the same for your 6 as they are for the 8s. Same options for transmissions with the 6s and 8s, too. LOTS of good info there that will apply equally to your V6.
Lots of odds 'n ends I'm not thinking of right now, but you'll have to deal with along the way...
Good Luck!
Decisions and hurdles to overcome:
Oil pan- the V6 oil pans, to my knowledge, were all rear sump. That puts the sump right where the steering linkage is. Some fabrication on the pan and pickup will be necessary.
Engine mounts- more fabrication, nobody makes swap mounts for the V6. Magnum V8s had the LA style mounts in addition to the mid-motor Magnum mounts, the 6s I believe don't.
Exhaust- the manifolds should work, people have been running the V8 Magnum manifolds with a little judicious grinding and engine shimming. The big drawback is that it was manual steering only- won't clear the power box. Now with the V6 being shorter in length, you just might get away with it with power steering. Pure conjecture on that.
Headers are a no-go, nobody makes them for your application, and you can't just mod the V8 headers by lopping off one header tube on each side even though the 6 is basically an 8 with 2 cylinders deleted- they omitted the 2 rear cylinders, (edit- rear on driver's side, front on pass. side) so that would move the entire header rearward by a substantial amount, giving you all kinds of clearance issues. I suppose you could make your own, though...
Electronics- I assume you'll be running the factory EFI (rotsa ruck finding one of the old DC 4bbl manifolds and/or electronic distributors), so start reading up on the computer/wiring requirements for Magnum EFI in the "Magnum Swaps" forum- the wiring and fuel requirements are the same for your 6 as they are for the 8s. Same options for transmissions with the 6s and 8s, too. LOTS of good info there that will apply equally to your V6.
Lots of odds 'n ends I'm not thinking of right now, but you'll have to deal with along the way...
Good Luck!
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As already mentioned, your /6 trans is a 904 but won't work anyway as the bolt pattern is different. Because the 3.9 was based on the small block, there is a lot of commonality.
Easiest thing might be to just rebuild the 3.9 trans. Especially if it is a 4 speed OD. Done.
Seems everyone automatically wants to increase the power. You could send the cam to Oregon Cam and get it reground. You could get the FI to work or if it's carbureted, go bigger.
I love the 225 in my 64 Valiant but if I ever did a swap, I'd go Pentastar 3.6. 300 HP stock.
Easiest thing might be to just rebuild the 3.9 trans. Especially if it is a 4 speed OD. Done.
Seems everyone automatically wants to increase the power. You could send the cam to Oregon Cam and get it reground. You could get the FI to work or if it's carbureted, go bigger.
I love the 225 in my 64 Valiant but if I ever did a swap, I'd go Pentastar 3.6. 300 HP stock.
pishta
I know I'm right....
I want to thank eveyone on here for all the good ideas and suggestions, however, I have decided AGAINST the 3.9 V-6 swap for my '73 Scamp! I just joined this group and have found out in a short time that it is going to provide me with loads of information that will be greatly appreciated! I am going to start me another post with my next thoughts for my '73 Scamp. Look for me to put it out there and fire away with your suggestions and comments!
Dart64GT put a 3.9 Magnum in his early A and it worked well. Anyone ever swap in a V6 into their Abody?
There’s no group better than here in FABO with Hughes kudos to slantsix.org as being extremely focused and excellent.
If you're concerned about your mechanical skills, take some time and watch this young guy work on these RHD Barracudas
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