Need some guidance on transmission/flexplate/torque convertor

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dartboy09again

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Hello all.
I am a little confused, getting conflicting information on my 360 magnum swap.
I bought a 1997 donor ram, have the 360 magnum engine, the flex plate, and the stock ram torque convertor.
I want to bolt this to a 1972 727 auto.
I am confused on the setup. I am being told that I need a weighted flex plate and i am good to go, or I am being told that I need a weighted torque convertor and good to go.
Now, I am being told that the ram torque convertor will not fit in the 727 (I have not tried this yet).
I assumed that because the engine, flexplate, and torque convertor all came from the same truck, i was good to just connected the 727.
Any advice?
 
The 97 would have a lock-up convertor correct? If so, I don't think it would even work on the non-lock up 727. The transmission input shafts would be different between the 518 and the 727.
 
You need a flexplate for the 5.9 magnum, and a neutral balanced/non-weighted converter for a 727.
 
dartboy09again said:
Hello all.
I am a little confused, getting conflicting information on my 360 magnum swap.
I bought a 1997 donor ram, have the 360 magnum engine, the flex plate, and the stock ram torque convertor.
I want to bolt this to a 1972 727 auto.
I am confused on the setup. I am being told that I need a weighted flex plate and i am good to go, or I am being told that I need a weighted torque convertor and good to go.
Now, I am being told that the ram torque convertor will not fit in the 727 (I have not tried this yet).
I assumed that because the engine, flexplate, and torque convertor all came from the same truck, i was good to just connected the 727.
Any advice?
Click to expand...
In '97, the 5.9 Magnum used a weighted flex plate. As stated, the '97 torque convertor will not work with a '72 727. What you need is a 727 neutral balance (not from an LA 360, as they had weights welded to the convertor for balance- which, btw, is completely different from the balance for a 5.9 Magnum- more on this later) torque convertor, which you will bolt to your 5.9 flex plate. One hole in the flex plate will need to be oblonged (5 minute job with a rat-tail file) for the convertor to bolt up.
Now, about that LA 360 torque convertor. As mentioned, 360s had the balance weights welded to the convertor, 5.9s were balanced via the flexplate (from the factory), and so used a neutral balanced torque convertor. You can use an LA 360 TC if you remove the balance weights, located on the face (engine side) of the torque converrtor between the nounting lugs. Depending on year, there will either be 1 large or 2 smaller balance weights- remove them. That will make the TC "neutral balance".
If the TC comes from a late '72 or '73 340, you will encounter similar balance weight issues; address them the same as a 360.
Any 318 or '68- early '72 340 will be a neutral balance TC, and ready to use as-is.
Be wary of using a big block 727 convertor, as some of these used an 11" convertor which will NOT fit your Magnum flex plate.
 
Professor Fate said:
In '97, the 5.9 Magnum used a weighted flex plate. As stated, the '97 torque convertor will not work with a '72 727. What you need is a 727 neutral balance (not from an LA 360, as they had weights welded to the convertor for balance- which, btw, is completely different from the balance for a 5.9 Magnum- more on this later) torque convertor, which you will bolt to your 5.9 flex plate. One hole in the flex plate will need to be oblonged (5 minute job with a rat-tail file) for the convertor to bolt up.
Now, about that LA 360 torque convertor. As mentioned, 360s had the balance weights welded to the convertor, 5.9s were balanced via the flexplate (from the factory), and so used a neutral balanced torque convertor. You can use an LA 360 TC if you remove the balance weights, located on the face (engine side) of the torque converrtor between the nounting lugs. Depending on year, there will either be 1 large or 2 smaller balance weights- remove them. That will make the TC "neutral balance".
If the TC comes from a late '72 or '73 340, you will encounter similar balance weight issues; address them the same as a 360.
Any 318 or '68- early '72 340 will be a neutral balance TC, and ready to use as-is.
Be wary of using a big block 727 convertor, as some of these used an 11" convertor which will NOT fit your Magnum flex plate.
Click to expand...

This is correct. Also, concerning the flex plate bolt holes not lining up, some converters like my FTC converter will have dual bolt patterns and one set lined right up.
 
Existing 5.9 Magnum flex plate, 72 non weighted converter that is in your 727, oblong 1 hole in the Magnum flex plate so it will bolt up. No extra cost, just a few minutes labor ratting the one hole out. Well, maybe a little cost....buy a new front seal for the 727.
 
JDMopar said:
Existing 5.9 Magnum flex plate, 72 non weighted converter that is in your 727, oblong 1 hole in the Magnum flex plate so it will bolt up. No extra cost, just a few minutes labor ratting the one hole out. Well, maybe a little cost....buy a new front seal for the 727.
Click to expand...
Thanks for the info.
The 727 doesn't have its torque convertor unfortunately, so i'll need to obtain one somewhere. I don't wanna buy a new one just yet.
The transmission has been sitting for like 20 years, so a front seal may not be a bad idea.
 
dartboy09again said:
Thanks for the info.
The 727 doesn't have its torque convertor unfortunately, so i'll need to obtain one somewhere. I don't wanna buy a new one just yet.
The transmission has been sitting for like 20 years, so a front seal may not be a bad idea.
Click to expand...
Since you're in the hunt for a 727 convertor, in addition to the exceptions I noted above, you need to avoid the '67 and earlier TC, since those had a different input diameter and spline count, in addition to a different convertor nose diameter.
Lockup convertors started showing up in some (not all) 727s in '78, lockups are again unuseable in your base 727. Lockup/OD trannies (A518/46RH and later the 46RE) started showing up in '88- this is the TC you currently have and can't use.
So, your useable window for 727 convertors is '68-'88, avoiding the lockups.
Happy Hunting!
 
Professor Fate said:
Since you're in the hunt for a 727 convertor, in addition to the exceptions I noted above, you need to avoid the '67 and earlier TC, since those had a different input diameter and spline count, in addition to a different convertor nose diameter.
Lockup convertors started showing up in some (not all) 727s in '78, lockups are again unuseable in your base 727. Lockup/OD trannies (A518/46RH and later the 46RE) started showing up in '88- this is the TC you currently have and can't use.
So, your useable window for 727 convertors is '68-'88, avoiding the lockups.
Happy Hunting!
Click to expand...
I'm thinking of this one, if it will work with my application.
I don't want to spend a bunch right now on a TC.

https://www.napaonline.com/en/p/PMTCR22?impressionRank=1
 
As someone who has done exactly what you're looking to do, I can tell you Professor Fate's comments are bang on. I would only add something to this:

Professor Fate said:
5.9s were balanced via the flexplate (from the factory), and so used a neutral balanced torque convertor.
Click to expand...

This is true for 5.9s from 1996 to 2003. From 1993 to 1995 they had a neutral flex plate and the weight on the torque converter. I suspect the good Professor already knows this based on the way he started his comment with "In '97, the 5.9 Magnum used a weighted flex plate..." but I'm just clarifying for you and any future member that reads this thread.

The other thing I'll say is regarding this:
Professor Fate said:
Lockup/OD trannies (A518/46RH and later the 46RE) started showing up in '88- this is the TC you currently have and can't use.
Click to expand...

Some early A500/42RH and A518/46RH transmissions did not have lockup converters. I'm not sure which of those didn't have lockup, all I know for sure is that the diesel transmissions (47RH) from 1993 and earlier did not have lockup. I also don't know if the non-lockup A500/42RH and A518/46RH would work in a 727, but my guess is it would work.
 
autopar3000 said:
As someone who has done exactly what you're looking to do, I can tell you Professor Fate's comments are bang on. I would only add something to this:



This is true for 5.9s from 1996 to 2003. From 1993 to 1995 they had a neutral flex plate and the weight on the torque converter. I suspect the good Professor already knows this based on the way he started his comment with "In '97, the 5.9 Magnum used a weighted flex plate..." but I'm just clarifying for you and any future member that reads this thread.

The other thing I'll say is regarding this:


Some early A500/42RH and A518/46RH transmissions did not have lockup converters. I'm not sure which of those didn't have lockup, all I know for sure is that the diesel transmissions (47RH) from 1993 and earlier did not have lockup. I also don't know if the non-lockup A500/42RH and A518/46RH would work in a 727, but my guess is it would work.
Click to expand...
So if I got to Napa or some parts store and ask for a TC for a 1972 318, would that work?
 
dartboy09again said:
So if I got to Napa or some parts store and ask for a TC for a 1972 318, would that work?
Click to expand...
As long as it's for a 727- the majority of 318s would have had a 904 in pass. cars. If you ask for, say, a '71 340 TC (ALL 340 autos were 727s) it would be neutral balance and probably have a little higher stall speed for a similar amount of money.
 
Ask the parts stores if they sell Daaco remanufactured torque converters. I put one like in the link below in a 71 Challenger with a warmed up 360 LA motor. The one in the link is the same specs as a Chrysler Hemi "J" converter. It worked well in my car. It's enough converter, but not so much that it doesn't work well in a street car.
 
autopar3000 said:
This is true for 5.9s from 1996 to 2003. From 1993 to 1995 they had a neutral flex plate and the weight on the torque converter. I suspect the good Professor already knows this based on the way he started his comment with "In '97, the 5.9 Magnum used a weighted flex plate..." but I'm just clarifying for you and any future member that reads this thread.
Click to expand...
Yeah, I wanted to keep it related to what he already had on hand... since he said he was already confused by conflicting information, I didn't want to add too much to his confusion- let's face it, there's a lot of variables when we start swapping stuff around :eek: and we don't want to scare everybody away!
 
Really glad I found this thread at the last minute. I just finished my 360 magnum build for my cordoba and was planning on putting it in any day now with the magnum torque converter. Just to reiterate, any 727/318 torque converter will work from 68-88?

20220528_135124.jpg


20230508_054948.jpg
 
Yes, just use the flex plate from your 5.9 Magnum and slot one hole out so all 4 bolts will fit. I'd suggest holding the flex plate up against the converter while it is still out of the car, put the 3 bolts that will fit in, and then scribe the flex plate at the 4th hole where it needs elongated. After you get that one hole filed out to fit, then go ahead with the install. It should fit at any position you line it up, but being gun shy about converter bolts not lining up, I would mark both the flex plate and the converter at one bolt hole, put that one on the bottom when you start putting the bolts in and you will be sure all 4 line up right. Hope this helps.
 
The 318 magnum is internally balanced isn't it? If it's internally, don't you need to pull any weights off of the converter? The 5.9 is externally balanced, and the tq will need to be neutral I believe.
 
Yep, use the Magnum flex plate either way and just make sure you have the correct one for a 5.2 or a 5.9 because the 5.9 flex plate has the weights on it and the 5.2 doesn't. No weights on the converter for either one. You will need to rat one hole out for LA converters on either flex plate.

:thumbsup:
 
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