Want to put a magnum 5.9 in my 70 dart.

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redbeard

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Hello, first post so be gentle on me . I have searched but not finding the info I am looking for.

I have 1970 dart swinger that I want to put a magnum 5.9 in with what transmission I am not sure of yet. What's my best/ least amount of cutting and welding needed for this swap.

I have the conversation mounts for the engine.
 
It’s basically the same as the LA motor. The differences are: block side motor mount bosses were added. The Assy drive item on the front of the block are serpentine belt. The cam was changed to a roller setup, the rockets are pedestal style and the oiling of the top end changed.

There is 3 options for transmissions from a stock form.

NP - a833 4 speed
904 “small” automatic
727 “large” automatic
 
I did a 70 with a later spoolmount k member and a 727.
I added an electric fuel pump and had to grind some ribs off the block to make the la headers fit.
I used a 90 degree oil filter adapter and knocked the locating tab off of it so I could turn it for best clearance.

Slot one hole in the magnum flexplate to match the LA converter.
 
redbeard said:
Hello, first post so be gentle on me . I have searched but not finding the info I am looking for.

I have 1970 dart swinger that I want to put a magnum 5.9 in with what transmission I am not sure of yet. What's my best/ least amount of cutting and welding needed for this swap.

I have the conversation mounts for the engine.
Click to expand...
Welcome to the site!

What you are attempting is pretty much a straight up swap and really about as easy as it gets. They came with small blocks and the 360/5.9 is no bigger in size than any of the others. You can run any of the transmissions you want - 904, 727, 3 speed, 4 speed
 
BUT-
Be aware of the difference in the 5.9's balance.
It takes it's own flexplate or flywheel, which in general does not interchange with any other LA engine (or the 5.2 Magnum either, for that matter).
Much of the rest will depend on whether you decide to run the Stock Magnum's EFI, or convert to carburetion.
"Least amount of cutting and welding" will depend on what your Dart is currently equipped with.
 
Since you said you've already gotten "conversion mounts", I'll ASSUME you currently have a slant 6, which in turn, would have an A904 if it's an automatic transmission.
Then your easiest swap would be with a '68 and later smallblock A904 (your slant 6 transmission will not fit the LA or Magnum engine block) transmission, which would allow ALL your existing shift linkage, speedometer drive, and driveshaft to swap right over to your new setup.
All you would need to fabricate or adapt would be your kickdown linkage, and oval out one flexplate hole on the 5.9 flexplate to fit the 904 convertor, as mentioned above. And the addition of an appropriate V8 radiator.
As I said, this will be dependent on if you're going to run the factory EFI or not.
Also see Magnumswap.com for additional info.
Seriously consider a heavier rear end (if the stock slant 6 7.25 rear), bigger brakes (if the stock 9" drums), and heavier front torsion bars.
 
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Professor Fate said:
BUT-
Be aware of the difference in the 5.9's balance.
It takes it's own flexplate or flywheel, which in general does not interchange with any other LA engine (or the 5.2 Magnum either, for that matter).
Much of the rest will depend on whether you decide to run the Stock Magnum's EFI, or convert to carburetion.
"Least amount of cutting and welding" will depend on what your Dart is currently equipped with.
Click to expand...
Yeah I ran into this with a magnum based motor recently. If he decides to go 904 you gotta pay $$$ for a flex plate. I tried the stock magnum flexplate but it wouldn’t fit my PTC converter. Something for him to keep in mind if he is going with an aftermarket torque converter.

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MidnightSwinger said:
Yeah I ran into this with a magnum based motor recently. If he decides to go 904 you gotta pay $$$ for a flex plate. I tried the stock magnum flexplate but it wouldn’t fit my PTC converter. Something for him to keep in mind if he is going with an aftermarket torque converter.

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And that will also depend on whether EFI is retained- then the stock flexplate MUST be used for its crank sensor slots.
 
Professor Fate said:
And that will also depend on whether EFI is retained- then the stock flexplate MUST be used for its crank sensor slots.
Click to expand...
I didn’t know that, thank you for the info. You’d have to probably run a stock converter in that instance, of find a manufacturer that makes a converter that works with a stock FP.
 
No cutting or welding required really. Perhaps some mid mount engine mount boss grinding to make headers fit properly. No big deal there.

Check magnumswap.com. They have tones of info on this.

I have a mopar crate motor magnum based in this car and it was all fairly easy to do.

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Professor Fata made great remarks.

I put a 5.9 in my ride w/a 727 using a B&M flew plate designed for this balance of the 5.9 and a zero balance converter.
 
318willrun said:
Is that a "904" thing or a PTC thing? I've used the same flexplate for both 904 and 727's
Click to expand...
I think it’s because it’s their higher end/race 9.5”. It’s close to fitting, it could fit if you beveled the crap out of it.

I assume that PTC designs this converter with an aftermarket/sfi flex plate in mind. Just my hypothesis as I bought the converter used and then the problem presented itself.

If I’m totally honest I wasn’t aware that the magnum was different from the LA in that regard, so it’s been trial and error for me.
 
rumblefish360 said:
Professor Fata made great remarks.

I put a 5.9 in my ride w/a 727 using a B&M flew plate designed for this balance of the 5.9 and a zero balance converter.
Click to expand...
You must have bought it a while ago to say the least. They’ve been discontinued now for some time. I also have the proper B&M flex plate for the magnum swap. I think the old B&M part number is 10242. This is the one for the swap.

They haven’t been available for a while BUT Mancini says they have one. Not sure who the maker of it would be. Mancini Racing - Balanced Flex Plate
They also list one for magnum to 904 trans
 
4mulas said:
You must have bought it a while ago to say the least. They’ve been discontinued now for some time. I also have the proper B&M flex plate for the magnum swap. I think the old B&M part number is 10242. This is the one for the swap.

They haven’t been available for a while BUT Mancini says they have one. Not sure who the maker of it would be. Mancini Racing - Balanced Flex Plate
They also list one for magnum to 904 trans
Click to expand...
I had a conversation with Mancini Racing and they verified they are offering the Magnum balance offset flex plates. They are having a local company modify/add the offset notch. They did not have one on hand when I spoke to them so I have not seen one in person yet. If ordering one, make sure you are very specific that is is 5.9 Magnum balance you are seeking. This is a new offering to them and the salesmen on the phones may not be fully up to speed on this yet.
 
4mulas said:
You must have bought it a while ago to say the least. They’ve been discontinued now for some time. I also have the proper B&M flex plate for the magnum swap. I think the old B&M part number is 10242. This is the one for the swap.

They haven’t been available for a while BUT Mancini says they have one. Not sure who the maker of it would be. Mancini Racing - Balanced Flex Plate
They also list one for magnum to 904 trans
Click to expand...

The company PRW sells what’s needed. I got one for the wife’s car and it’s SFI rated.
 
rumblefish360 said:
The company PRW sells what’s needed. I got one for the wife’s car and it’s SFI rated.
Click to expand...
Do you remember the part numbers? I have looked at PRW stuff and don't remember seeing Magnum balance. Some of there stuff is listed weird with the title saying FORD and the details and picture showing Mopar, but I still don't see it. I hope I am just missing it because that would be a better cost than the companies buying one and modifying it at a higher price.
 
I doubt I have the number on paper anymore. It’s been a long time.
 
Thank you everyone for your responses. Definitely liked the magnum swap page lots of good information there.

Guess I left out some details. I plan to do carb setup on the motor keeps it simple and can be upgraded as money allows. Car is automatic I did want to have overdrive but the floor is in pretty good shape and don't want to chop it up. So will probably be going with just a 904 transmission.

Do you guys run electric fans or use the stock fan? The plan for the car is to be a driver.
 
redbeard said:
Thank you everyone for your responses. Definitely liked the magnum swap page lots of good information there.

Guess I left out some details. I plan to do carb setup on the motor keeps it simple and can be upgraded as money allows. Car is automatic I did want to have overdrive but the floor is in pretty good shape and don't want to chop it up. So will probably be going with just a 904 transmission.

Do you guys run electric fans or use the stock fan? The plan for the car is to be a driver.
Click to expand...
If you do want to swap to EFI later, you can always use a Dual Sync dizzy to get both cam and crank position sensors to replace the factory crank position sensor.

Remember that the Magnums need radiators have a driver's side inlet and a passenger side outlet. I used a thermal clutch with a 5 blade fan from a later model Cherokee. The came with an 11 blade fan too, but that thing made the car sound like an airplane.

Airbox2.JPG
 
redbeard said:
Thank you everyone for your responses. Definitely liked the magnum swap page lots of good information there.

Guess I left out some details. I plan to do carb setup on the motor keeps it simple and can be upgraded as money allows. Car is automatic I did want to have overdrive but the floor is in pretty good shape and don't want to chop it up. So will probably be going with just a 904 transmission.

Do you guys run electric fans or use the stock fan? The plan for the car is to be a driver.
Click to expand...
I'm using a clutch fan off of the same 97 ram 1500.
I haven't gotten a shroud on it yet though. I kept the serp belt drive.
 
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OP, are you keeping the front serpentine setup, or switching to one of the two different LA timing cover/water pump/pulley setups?
That will determine what you need for a radiator/shroud.
If you're keeping the Magnum's serpentine setup, make sure the 4 bbl. manifold you get has the provisions on it for mounting the serpentine setup, and has the thermostat offset to the driver's side for bracket clearance.
 
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