magnum to 904 help

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magnumdust

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I'm putting a 5.9 magnum into my duster and i've run into a snag. I called mancini racing to buy the flex plate i need to mate my 5.9 to my 904 and according to them, B&M no longer makes the appropriate flex plate?

The guy said that they only offer a flex plate for the 727 transmissions.

What can i do? I'm not looking to source a 727 transmission.
 
i think there is but i was dealing with a 727 tranny and to mount the engin to the torque it took a doffrent flex plate.
 
LA and Magnum are different balance. 93 to 95 5.9 magnum stock flexplate will work.
John
 
If you still have the stock flexplate from your magnum it will work. You will have to slightly elongate one bolt hole.

If not, you can run a neutral balance flexplate and get a converter with the Magnum balance on it.
 
In the early Magnum years, i think up to 97-98, the flexplate didn't have the weights on them, they were on the converter, If you have this flexplate with "no" weights, i'd scout the junkyards or post on the wanted section on here & moparts for the flexplate with the weights, I found one from a member for 15.00, then you can run a "N" balanced converter, & like LXguy mentioned, you'll need to elongate one of the holes about an 1/8".

I opened mine up to except the 7/16" bolts, added insurance, then when you purchase your aftermarket converter, get it with the holes opened up to 7/16", make sure you get the bolts with it, they can be hard to find.
 
I just happen to have a 94 5.9 flex plate bolted to a magnum that I am not going to use.
PM me if you can use it.
 
JoeDust451 said:
In the early Magnum years, i think up to 97-98, the flexplate didn't have the weights on them, they were on the converter, If you have this flexplate with "no" weights, i'd scout the junkyards or post on the wanted section on here & moparts for the flexplate with the weights, I found one from a member for 15.00, then you can run a "N" balanced converter, & like LXguy mentioned, you'll need to elongate one of the holes about an 1/8".

I opened mine up to except the 7/16" bolts, added insurance, then when you purchase your aftermarket converter, get it with the holes opened up to 7/16", make sure you get the bolts with it, they can be hard to find.
Click to expand...

ok, so i have a 99' magnum and luckily i still have the weighted flex plate. So all i need to do is elongate one of the holes and run a Neutral balanced converter? Which i hope is in there since its another 360 coming out of the car.

Is there any particular hole i need to elongate and is that 1/8" towards the crank or towards the outside?
 
magnumdust said:
ok, so i have a 99' magnum and luckily i still have the weighted flex plate. So all i need to do is elongate one of the holes and run a Neutral balanced converter? Which i hope is in there since its another 360 coming out of the car.

Is there any particular hole i need to elongate and is that 1/8" towards the crank or towards the outside?
Click to expand...

It'll be one side or the other, not "up or down", Looks like your good to go, all you need to do is possition the converter with the hub faceing down (just don't tear it up) use a box or piece of hard foam to support the converter, having the bolt holes faceing up, then lay the flexplate on the converter (weights/lip down), then spin the flexplate untill you can put in 3 bolts (make sure it centers), then you'll see where you need to elongate the one hole, make sure all bolts go in before assemble. If your going to use the existing converter thats in it, make sure it has "no" weights, if it does, you'll need to knock them off. Use the stock H balancer also.

Another issue you "might" have, is putting the starter on, the older 904s/727s had the starter possitioned a bit different then the newer trannys, Check & see if there is a "boss" on the block where the starter will be, this boss should have a hole in it, if so, you'll most likely have to trim off about a 1/4" or more so the starter fits flush & not cocked. I had to do this on my 95 magnum 360, seeing yours is a 99, it may not have it, i didn't realize this problem untill the engine was in place & i was installing the starter :-|, but i was able to sneak my die grinder in there & trim it down thank god.
 
JoeDust451 said:
It'll be one side or the other, not "up or down", Looks like your good to go, all you need to do is possition the converter with the hub faceing down (just don't tear it up) use a box or piece of hard foam to support the converter, having the bolt holes faceing up, then lay the flexplate on the converter (weights/lip down), then spin the flexplate untill you can put in 3 bolts (make sure it centers), then you'll see where you need to elongate the one hole, make sure all bolts go in before assemble. If your going to use the existing converter thats in it, make sure it has "no" weights, if it does, you'll need to knock them off. Use the stock H balancer also.

Another issue you "might" have, is putting the starter on, the older 904s/727s had the starter possitioned a bit different then the newer trannys, Check & see if there is a "boss" on the block where the starter will be, this boss should have a hole in it, if so, you'll most likely have to trim off about a 1/4" or more so the starter fits flush & not cocked. I had to do this on my 95 magnum 360, seeing yours is a 99, it may not have it, i didn't realize this problem untill the engine was in place & i was installing the starter :-|, but i was able to sneak my die grinder in there & trim it down thank god.
Click to expand...

ok i'll check for that boss, but i think i'm safe.

Oddly enough i found this thread, a 99 magnum into a 73 duster:
http://www.forabodiesonly.com/mopar/showthread.php?t=41302&highlight=magnum+serpentine

A very detailed build and the OP did not bring up an issue with the block.
 
When I did mine I elongated one hole and used a converter from a slant 6. works great.
 
mustangdart said:
When I did mine I elongated one hole and used a converter from a slant 6. works great.
Click to expand...

I did exactly the same and havent installed my engine/tranny yet. What engine do you have the /6 converter behind(also what are your dyno/estimated torque figures? and what is is stalling at
 
Kind of an old topic but i have 1 more Q:

Will elongating this hole throw off the balance of the flexplate?
 
magnumdust said:
Kind of an old topic but i have 1 more Q:

Will elongating this hole throw off the balance of the flexplate?
Click to expand...

Nope, your not really taking much off to affect anything, if this makes you feel at ease, after i got mine running, it was by far one of the smoothest SB mopar engine i ever owned :icon_smi:.
 
Regarding the starter, I don't know if it had something to do with using a Magnum block with a 904, but I managed to burn up 3 starters in a 4 month time frame. The overrun clutch was mangled in each one. Now I don't know if it had something to do with the way I was installing it, or if they just didn't line up quite right, but it was a pita there for a while. After the 3rd starter went I decided to try a Dakota starter and it's been fine ever since, which has been about 3 months now. Just thought I would share.
 
UOP said:
Regarding the starter, I don't know if it had something to do with using a Magnum block with a 904, but I managed to burn up 3 starters in a 4 month time frame. The overrun clutch was mangled in each one. Now I don't know if it had something to do with the way I was installing it, or if they just didn't line up quite right, but it was a pita there for a while. After the 3rd starter went I decided to try a Dakota starter and it's been fine ever since, which has been about 3 months now. Just thought I would share.
Click to expand...

Good to know, i planned to run the dakota starter anyways because my understanding is that they're a bit of a step from the original starts. Plus, my starter is dying anyways.
 
I ran a mini starter on mine. I had to do a very slight bit of grinding on the block to make it fit correctly.
 
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