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#2459033 - 02/28/18 04:37 PM 360 Magnum balance question...
FC7Challenger Offline
member

Registered: 10/21/17
Posts: 4
Loc: Canada
I bought a challenger with a 360ci/380hp crate motor. I am in the process of swapping the 727 to a a518. When I pulled the trans out,I notice it had a standard non balanced flex plate and a non balanced torque convertor. With all the research I have done, this motor should need a weighted flex plate.
I have had the car for over 12 years, spun it well over 6000rpm lots and never felt an unbalanced feeling ever. I am told if it isn't correct, you will know!
Does this make sense to anyone? can the 360 be internally balanced?
any thoughts or advise would be appreciated, thx....
here's the flex plate and balancer.........


Attachments
flex.jpg

balancer.jpg




Edited by FC7Challenger (02/28/18 04:39 PM)

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#2459054 - 02/28/18 05:31 PM Re: 360 Magnum balance question... [Re: FC7Challenger]
RapidRobert Offline
Circle Track

Registered: 11/20/03
Posts: 33628
Loc: Lincoln Nebraska
Welcome here! Yes a 360 can be internally balanced (takes Mallory metal) cuz I had one (360 LA) internally balanced so I could run any neutral converter. tho in hindsight it may have been cheaper to externally balance with the offset plate THEN run any neutral converter. As you know mags are different & I would wait for others to chime in. You'rs may already have been balanced.
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#2459075 - 02/28/18 06:33 PM Re: 360 Magnum balance question... [Re: FC7Challenger]
John_Kunkel Offline
I Live Here

Registered: 01/20/03
Posts: 19299
Loc: Rio Linda, CA
I would think that, if it was internally balanced, they wouldn't use the external balance damper. shruggy

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#2459082 - 02/28/18 06:49 PM Re: 360 Magnum balance question... [Re: FC7Challenger]
EV2Bird Online   penguin-006
No more politics

Registered: 06/23/14
Posts: 3742
Loc: Kansas Roads Between 0 and 140...
Im a bit surprised myself, even with the lighter bobweight of a magnum a cast crank 360 mag with light parts would still take costly mallory.

Did that crate motor spec with a steel crank? That might make the difference.

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#2459122 - 02/28/18 08:05 PM Re: 360 Magnum balance question... [Re: FC7Challenger]
Michael Ecks Offline
super stock

Registered: 01/20/03
Posts: 1093
Loc: Columbus, GA
Is this the magnum version?

Here's from a Mopar Muscle article where the dynoed a 360/380 magnum crate.

"Complete From Oil Pan To Intake, The Crate Just Needs Accessories, Pulleys, Carb, Headers, Plugs And Wires, And It's Ready To Fire. The 360 Magnum Has A Specific Balance Factor, Different From The Earlier 360s. The Damper Comes With It, But The Flywheel, Flexplate, Or Converter Does Not. When Ordering, Be Sure To Specify Magnum Balance."

http://www.hotrod.com/articles/mopp-0303...e_buildup-crate
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#2459153 - 02/28/18 08:45 PM Re: 360 Magnum balance question... [Re: FC7Challenger]
FC7Challenger Offline
member

Registered: 10/21/17
Posts: 4
Loc: Canada
here is the only picture of the crank I have, had to do a rear main seal when I bought it and snapped a quick pic on my back...
thanks everyone for your input, I have the proper flex plate, but I am unsure if I should use it.


Attachments
crank.jpg



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#2459163 - 02/28/18 08:55 PM Re: 360 Magnum balance question... [Re: Michael Ecks]
FC7Challenger Offline
member

Registered: 10/21/17
Posts: 4
Loc: Canada
yes, it's the magnum, and yes I've seen that article. Just trying to figure why my motor is not externally balanced...
but thx

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#2459255 - 03/01/18 02:14 AM Re: 360 Magnum balance question... [Re: FC7Challenger]
Cab_Burge Offline
I Win

Registered: 08/23/03
Posts: 30814
Loc: Bend,OR USA
The hole drilled in the front rear counterweight behind the #2 rod tells me it is partially internally balanced confused work
Me thinks of the old mechanics adage, if it ain't broken don't fix it tsk work In other words if it wasn't shaking before now go forward as you had it before, especially on the flexplate and converter up twocents


Edited by Cab_Burge (03/01/18 02:17 AM)
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#2459258 - 03/01/18 02:26 AM Re: 360 Magnum balance question... [Re: FC7Challenger]
EV2Bird Online   penguin-006
No more politics

Registered: 06/23/14
Posts: 3742
Loc: Kansas Roads Between 0 and 140...
I have had the car for over 12 years, spun it well over 6000rpm lots and never felt an unbalanced feeling ever. I am told if it isn't correct, you will know!

yep and with what CAB posted and since you had it apart to change the real seal you would of noticed a ugly rear main bearing if it were a problem.

I also noticed and posted in the pic, the second thin throw which is also used for balance drilling looks uneven, like filled and its not uncommon to add weight and then remove here or there.

Ir run it and not look back, good luck with your new trans.


Attachments
crank.jpg



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#2460536 - 03/03/18 01:23 PM Re: 360 Magnum balance question... [Re: EV2Bird]
FC7Challenger Offline
member

Registered: 10/21/17
Posts: 4
Loc: Canada
thanks for the help, I guess I'll just leave it the way it was.
the bearings looked really good when I pulled them out at that time...


Attachments
bearing.jpg




Edited by FC7Challenger (03/03/18 01:24 PM)

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#2460546 - 03/03/18 02:00 PM Re: 360 Magnum balance question... [Re: FC7Challenger]
polyspheric Offline
master

Registered: 10/10/07
Posts: 2614
Loc: New York
w/r/t partially internally balanced

Just a guess: adjusting the crank for greater balancing accuracy allows a standard (balanced, not neutral) damper and flex plate to be used (both factory and SEMA). If the adjustment were made to these external parts, they wouldn't work on any other engine.

In general any compensating weight should be located as closely as possible to the mass it's opposing to minimize "rocking couple". Do as much as you can with the counterweights, and only go external if that's not enough.

What about Mallory? The weight difference between the steel/iron you drill out and the Tungsten alloy you replace it with is sometimes not enough to correct the balance internally, unless the whole crank is full of holes: $$$.
If you're pretty close and want to use neutral external parts, the same (drill out and fill) process can be used with lead instead of tungsten - you just have to use more of it (weighs less than Tungsten).
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#2460668 - 03/03/18 09:07 PM Re: 360 Magnum balance question... [Re: FC7Challenger]
cudaman1969 Offline
master

Registered: 01/25/04
Posts: 4251
Loc: fredericksburg,va
I have a 426 Hemi crank with every journal full of lead and straps of steel welded over the lead to keep in there. Craziest thing I ever saw


Edited by cudaman1969 (03/04/18 09:42 AM)

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#2460718 - 03/03/18 11:27 PM Re: 360 Magnum balance question... [Re: FC7Challenger]
RTSrunner Offline
pro stock

Registered: 11/03/03
Posts: 1323
Loc: Pittsburgh,PA
Originally Posted By FC7Challenger
I bought a challenger with a 360ci/380hp crate motor. I am in the process of swapping the 727 to a a518. When I pulled the trans out,I notice it had a standard non balanced flex plate and a non balanced torque convertor. With all the research I have done, this motor should need a weighted flex plate.
I have had the car for over 12 years, spun it well over 6000rpm lots and never felt an unbalanced feeling ever. I am told if it isn't correct, you will know!
Does this make sense to anyone? can the 360 be internally balanced?
any thoughts or advise would be appreciated, thx....
here's the flex plate and balancer.........


That's not a "Magnum" flexplate on your engine,it would be more of a circular unit with a balance weight on it.The Magnum also uses less balance weight than the LA 360 engine. The LA engine has the balance weight welded on the torque converter.Odd that it doesn't vibrate or show any measurable wear.

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#2460841 - 03/04/18 09:56 AM Re: 360 Magnum balance question... [Re: RTSrunner]
cudaman1969 Offline
master

Registered: 01/25/04
Posts: 4251
Loc: fredericksburg,va
Originally Posted By RTSrunner
Originally Posted By FC7Challenger
I bought a challenger with a 360ci/380hp crate motor. I am in the process of swapping the 727 to a a518. When I pulled the trans out,I notice it had a standard non balanced flex plate and a non balanced torque convertor. With all the research I have done, this motor should need a weighted flex plate.
I have had the car for over 12 years, spun it well over 6000rpm lots and never felt an unbalanced feeling ever. I am told if it isn't correct, you will know!
Does this make sense to anyone? can the 360 be internally balanced?
any thoughts or advise would be appreciated, thx....
here's the flex plate and balancer.........


That's not a "Magnum" flexplate on your engine,it would be more of a circular unit with a balance weight on it.The Magnum also uses less balance weight than the LA 360 engine. The LA engine has the balance weight welded on the torque converter.Odd that it doesn't vibrate or show any measurable wear.

I just removed the trans from an 01 5.9 magnum and the flex-plate has the senser pickup flange-holes around the edge. Converter has no weights and no weighting on the flexplate that I could see either. I do have the right B&M flexplate on my 05-5.9 hanging on the engine stand. I know the pistons are different in the 360-380 hp engine, maybe why a regular plate is used. I'll try to weight the difference between the stock and 380 piston.

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#2461290 - 03/04/18 10:51 PM Re: 360 Magnum balance question... [Re: cudaman1969]
RTSrunner Offline
pro stock

Registered: 11/03/03
Posts: 1323
Loc: Pittsburgh,PA


I just removed the trans from an 01 5.9 magnum and the flex-plate has the senser pickup flange-holes around the edge. Converter has no weights and no weighting on the flexplate that I could see either. I do have the right B&M flexplate on my 05-5.9 hanging on the engine stand. I know the pistons are different in the 360-380 hp engine, maybe why a regular plate is used. I'll try to weight the difference between the stock and 380 piston. [/quote]

I guess the crate motor could have a different balance factor,odd that the crank balancer is for external balance and a zero flexplate.As someone said it could be partialy internal balance.

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#2461473 - 03/05/18 11:16 AM Re: 360 Magnum balance question... [Re: RTSrunner]
cudaman1969 Offline
master

Registered: 01/25/04
Posts: 4251
Loc: fredericksburg,va
Originally Posted By RTSrunner


I just removed the trans from an 01 5.9 magnum and the flex-plate has the senser pickup flange-holes around the edge. Converter has no weights and no weighting on the flexplate that I could see either. I do have the right B&M flexplate on my 05-5.9 hanging on the engine stand. I know the pistons are different in the 360-380 hp engine, maybe why a regular plate is used. I'll try to weight the difference between the stock and 380 piston.


I guess the crate motor could have a different balance factor,odd that the crank balancer is for external balance and a zero flexplate.As someone said it could be partialy internal balance. [/quote]
Meant to add the stock piston are dished and the 380 is flattop with those coated inserts on the skirt.

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