5.9 Magnum out of manual truck going to work?

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Justin Angle

Justin Angle

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Hey guys I just put a deposit down on a Magnum motor out off a Ram 3500 manual transmission truck. This is going into a Duster. I read the 5.9s are externally balanced and balance themselves through the flywheel. I won't be getting a flywheel so can i just use anyone from a junkyard or does it need to be balanced to match my specific motor. i plan on putting a 904 auto behind.

Do you guys for see any problems or is there anything I should know or look out for ahead of time before I jump all the way into this?...swapping out of a manual truck into automatic. And will a manual crank bolt to automatic transmission or is there any difference?

Thanks
 
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go back into the old posts here about magnum swap. the best site to find everything you need to know about the swap. i have learned soooo much it makes my head swim.
 
Get a flywheel for the 5.9 from rock auto and be sure your torque converter is a neutral converter so basically any for a stock 318 will work.
 
rumblefish360 said:
B&M sell a flex plate to solve this issue.
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^^THIS^^ LA engines have weighted torque converters to fully balance what is essentially an unbalanced engine, like a 360LA

Magnums are different. They use neutral balance converters, with weighted flexplates.

You cannot use an LA weighted converter because a 360LA is weighted different than a 5.9magnum, and so on.
 
67Dart273 said:
^^THIS^^ LA engines have weighted torque converters to fully balance what is essentially an unbalanced engine, like a 360LA

Magnums are different. They use neutral balance converters, with weighted flexplates.

You cannot use an LA weighted converter because a 360LA is weighted different than a 5.9magnum, and so on.
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Bingo! What he said ^^^^^^^^

Justin, the flex plate allows the use of a neutral or zero balance converter. The flex plate has a scallop cut out of it. It only bolt on one way to the crank and the converter only bolts on one way to the flex plate.

EZ peazy nice and easy.
 
Ok cool that sounds more simple than I thought it was gonna be thanks again for the info.
 
If you're going to use the fuel injection from the Magnum motor, you will need to swap the magnetic pickup thing that bolts to the back of the motor, and sits close to the flywheel. They are different lengths for a stick and automatic. Use a stock 5.9 flex plate as others have said. Be sure to line up the torque converter before you install the flex plate. Three of the bolt holes on the 904 converter will line up, and you will have to file the hole out on the flex plate so the 4th one fits.
 
JDMopar said:
If you're going to use the fuel injection from the Magnum motor, you will need to swap the magnetic pickup thing that bolts to the back of the motor, and sits close to the flywheel. They are different lengths for a stick and automatic. Use a stock 5.9 flex plate as others have said. Be sure to line up the torque converter before you install the flex plate. Three of the bolt holes on the 904 converter will line up, and you will have to file the hole out on the flex plate so the 4th one fits.
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Okay I'll do that and I'll be just converting it to carb so I guess the magnetic thing on the back of the motor I assume I can just remove it and do away with it altogether?
 
wanta68cuda said:
Get a flywheel for the 5.9 from rock auto and be sure your torque converter is a neutral converter so basically any for a stock 318 will work.
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Is there a difference in flywheels from the 5.9 mags '95 and down vs '96 and up??
 
318willrun said:
Is there a difference in flywheels from the 5.9 mags '95 and down vs '96 and up??
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This is misleading, and I'll address the flywheels in a minute. If you're running automatic, you want the flexplate, and NO flywheel. I think wantacuda68 is saying get the balanced flexplate for the 5.9. I doubt Rockauto will have that, I thought that they focused on OEM parts, which may nor work with your torque converter. Perhaps another member can chime in on that.

Yes, the flywheels changed (the tone ring mounting changed), but I'm not sure when and it doesn't matter. Our cars do NOT use the truck wheels in any shape or form.
 
Justin Angle said:
Okay I'll do that and I'll be just converting it to carb so I guess the magnetic thing on the back of the motor I assume I can just remove it and do away with it altogether?
Click to expand...

Yep, you won't need it if going to a carb. You will need a different distributor though. Mopar Performance, MSD, Pertronix, etc.
 
Rock Auto should have the flex plate that he needs for whatever year his 5.9 is. I have a 98 5.9 from a 3500 stick truck, and will be going to an automatic also. They had the right flex plate, as does Advance, NAPA, and pretty much all the big players in auto parts. He will have to rat one hole out in the flex plate to get his 904 neutral balance torque converter to bolt up. From that point on, the torque converter will bolt up in any position.
 
JDMopar said:
Rock Auto should have the flex plate that he needs for whatever year his 5.9 is. I have a 98 5.9 from a 3500 stick truck, and will be going to an automatic also. They had the right flex plate, as does Advance, NAPA, and pretty much all the big players in auto parts. He will have to rat one hole out in the flex plate to get his 904 neutral balance torque converter to bolt up. From that point on, the torque converter will bolt up in any position.
Click to expand...
Yes Rock Auto does carry it. I bought mine from them at a reasonable price too. And absolutely correct about the bolt hole!
 
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