How do I know which harmonic balancer I need ?

[Purepony]

Dodge 360 engine that was rebuilt. I believe they used the balancer of a 318 and it tends to vibrate at about 3200-3400 rpms while in neutral. Feel it while driving too.

how can I tell if they used a 318 balancer ? And which balancer would I need for a 360 dodge I believe 1978

thanks all

 

[4mulas]

360’s are externally balanced unless someone has rebuilt the engine making it internally balanced which isn’t likely on a stock rebuild. That said the harmonic damper on the 360 should have a visible portion of it it either removed or cast into it that makes it look offset and not the same all the way around.

A 318 one would look pretty much the same all the way around with maybe a few small holes drilled in it for balance purposes.

Does this make sense to you?

Sometimes if the torque converter is poorly balanced it can give the vibrations you speak if too.

 

[Purepony]

360’s are externally balanced unless someone has rebuilt the engine making it internally balanced which isn’t likely on a stock rebuild. That said the harmonic damper on the 360 should have a visible portion of it it either removed or cast into it that makes it look offset and not the same all the way around.

A 318 one would look pretty much the same all the way around with maybe a few small holes drilled in it for balance purposes.

Does this make sense to you?

Sometimes if the torque converter is poorly balanced it can give the vibrations you speak if too.

that the other problem it was rebuilt and I don’t think stock because it’s a 366

I really believe they used the balancer off my old 318. If I post a pic would you be able to see if it’s a 318 balancer?

I don’t have a converter it’s a 4 speed and it did this vibration even when I had the 904 auto

 

[4mulas]

A bored out but otherwise normal rebuild is considered a stock rebuild. I was referencing if the crank and was motor was changed/and internally balanced

Sure take some pictures and post . May be hard to tell as sometimes not both sides of the balancer will be e same

 

[Purepony]

A bored out but otherwise normal rebuild is considered a stock rebuild. I was referencing if the crank and was motor was changed/and internally balanced

Sure take some pictures and post . May be hard to tell as sometimes not both sides of the balancer will be e same

Yeah these guys just Slapped the engine together as quick as they could so I’m sure they probably used the 318 balancer

I’ll get some pics hopefully that will help.
I’m tempted to remove the balancer and check to see if it needs to be re sleeved
But let me get some pics first

thanks

 

[Curiousyellow71]

If its vibrating pull the flex plate cover off and see if you have the weights for a 360 on your torque convertor.
It's the most common thing to get off. I would look there first.

 

[Wietse]

its vibrating pull the flex plate cover off and see if you have the weights for a 360 on your torque convertor.
It's the most common thing to get off. I would look there first.

He just mentioned it has a 4 speed manual behind it now.
But as the OP says he had the same vibration when he used a 904 auto.

@Purepony: When you replaced the 904 trans, did you find a flexplate with a half moon shaped section cut out? Those supposed to be used on the external balanced 360's.
If that was there you have a big chance indeed the vibration is only caused by the harmonic balancer, since swapping flex plate to flywheel did not solve the vibration issue.
I am not sure if you used any specific flywheel for your application though, i would assume a flywheel for a 360 also supposed to be "balanced" for external balanced engines.
From what i found on Summit is that the flywheels are used for both applications and come with a removable weight that can be used/removed as required for internal & external balanced engines.
You really need to know what is there now to get rid of this unbalance, these vibrations can be very destructive for your engine depending on the severity.

 

[Curiousyellow71]

He just mentioned it has a 4 speed manual behind it now.
But as the OP says he had the same vibration when he used a 904 auto.

@Purepony: When you replaced the 904 trans, did you find a flexplate with a half moon shaped section cut out? Those supposed to be used on the external balanced 360's.
If that was there you have a big chance indeed the vibration is only caused by the harmonic balancer, since swapping flex plate to flywheel did not solve the vibration issue.
I am not sure if you used any specific flywheel for your application though, i would assume a flywheel for a 360 also supposed to be "balanced" for external balanced engines.
From what i found on Summit is that the flywheels are used for both applications and come with a removable weight that can be used/removed as required for internal & external balanced engines.
You really need to know what is there now to get rid of this unbalance, these vibrations can be very destructive for your engine depending on the severity.

Thanks... I missed that.
A oem flywheel to balance for a 360 has 3 large holes holes that don't go through visible from the front side...I believe. They did that as opposed to hanging a weight.
More then likely the previous 904 was meant to be behind a internally balanced 318. It would vibrate behind a 360 unless it had a aftermarket 360 convertor or the flexplate Wietse descibed.

 

[Purepony]

He just mentioned it has a 4 speed manual behind it now.
But as the OP says he had the same vibration when he used a 904 auto.

@Purepony: When you replaced the 904 trans, did you find a flexplate with a half moon shaped section cut out? Those supposed to be used on the external balanced 360's.
If that was there you have a big chance indeed the vibration is only caused by the harmonic balancer, since swapping flex plate to flywheel did not solve the vibration issue.
I am not sure if you used any specific flywheel for your application though, i would assume a flywheel for a 360 also supposed to be "balanced" for external balanced engines.
From what i found on Summit is that the flywheels are used for both applications and come with a removable weight that can be used/removed as required for internal & external balanced engines.
You really need to know what is there now to get rid of this unbalance, these vibrations can be very destructive for your engine depending on the severity.

If I remember correctly it was a cross shaped flex plate

I did use the correct 360 flywheel for the 833 because it had a weight option and I had another vibration after I installed it. I called the guy who sold it to me abd told me to get he weight, so I did and the other vibration went away, so now I’m left with the original vibration

 

[Wietse]

If I remember correctly it was a cross shaped flex plate

Likely the original setup from the 318.
I would try to get the proper balancer and check again, seems like you got the flywheel end sorted out then.

 

[Purepony]

Likely the original setup from the 318.
I would try to get the proper balancer and check again, seems like you got the flywheel end sorted out then.

I’m gonna post some pics of the balancer in a bit

 

[Wietse]

Below link shows a balancer that comes with several counter weights that can be used on various engines.
Depending on the application you need to select the right counter weight and bolt it on.
Your balancer, if correct, should have some sort of counter weight installed.
Likely it will be on the back side and cannot be seen without removing it.

https://www.summitracing.com/parts/pqx-2331841/make/dodge

But a picture might be helpful, see if you could find a brand/part number and maybe it is possible to find it is suitable for your engine or not.