Harmonic balancer and torque converter ?

[71scamp78]

Recently got a car with a 360 la engine with J heads and some sort of cam nothing radical. Has Turbo Action manual valve body trans. I have a pretty good vibration if I rev it sitting at idle. Just thinking maybe engine could have wrong balancer or torque converter. The balancer on front is a BHG and I can see a large weight on the back of it so I'm thinking it's correct. I think the torque converter should have weights if so how many. Going to pull the dust shield tomorrow and see what I got. The engine mount isolators have some cracks but I don't think it would cause this vibration. Any pointers are appreciated

 

[PRH]

If it doesn’t already have one, the easy button for the 360 converter is a weighted flex plate and neutral converter.

 

[71scamp78]

If it doesn’t already have one, the easy button for the 360 converter is a weighted flex plate and neutral converter.

Once I take the inspection cover off will I be able to see the weights if they are on the flex plate. I'd imagine they would be on the converter side

 

[PRH]

It may not have a weight.
The newer weighted flex plates just have a section missing on the side opposite of where you’d put the weight.

 

[71scamp78]

I mean it's got to be one or the other causing a bad vibration. Don't know anything that could cause that revenge an engine in neutral..

 

[PRH]

Like this:

 

[71scamp78]

Checked it out this morning it has a flex plate just like that. Here is a picture of the balancer. Maybe just order a new balancer but hate to throw away money.

 

[PRH]

Did you happen to look and see if the converter also has a weight on it(opposite the cutout)?

 

[71scamp78]

No i didn't not i will when I get home. I'll post soon my findings

 

[71scamp78]

I did not see any weights on the converter

 

[cudamark]

That's one ugly looking balancer. The add-on weight doesn't even look like it's mounted straight. Who knows if getting a stock replacement will help any or not, should the engine have a custom balance job of some sort.

 

[junkyardhero]

that balancer looks bobo AF. super sus. i'd be replacing that with a known entity before chasing my *** on a whole host of other laundry list items.

 

[4spdragtop]

I see a new HB in your future.

 

[PRH]

This type of situation shows up periodically.
Engine presumably rebuilt at some point, has a vibration, is theoretically externally balanced, has aftermarket parts installed related to the balance, and no paperwork.
The issue with auto trans Mopars in that situation is you can’t just slide the converter back to isolate that as being the problem or not.

Was it actually ever balanced with that flex plate/damper? Who knows.
I think the next step for me would be a new damper.

If that doesn’t cure it, I think the next steps will be harder.

 

[cudamark]

Yeah, pulling the rotating assembly out for a re-balance is not fun, but, sometimes that's the only way to get rid of the vibration.

 

[LO23M8B]

As said about start with the balancer.

 

[cudamark]

As said about start with the balancer.

He just needs to decide which balancer to go with. A neutral one for an internally balanced engine, or one for an externally balanced 360.

 

[junkyardhero]

He just needs to decide which balancer to go with. A neutral one for an internally balanced engine, or one for an externally balanced 360.

problem solved:

7.25" Chrysler 318/340/360 Harmonic Street Damper

Small Block Chrysler/Mopar 318/340/360 7.25'' Diameter Nodular Iron This damper is supplied as a neutral balance damper and comes with three bolt-in counterweights. This allows this one part number to fit four different small block Chrysler engines. The damper without any weight fits internally...

professional-products.com

 

[LO23M8B]

Maybe someone near him has one laying around that he could try. I think I'd try the 360 one first.

 

[LO23M8B]

problem solved:

7.25" Chrysler 318/340/360 Harmonic Street Damper

Small Block Chrysler/Mopar 318/340/360 7.25'' Diameter Nodular Iron This damper is supplied as a neutral balance damper and comes with three bolt-in counterweights. This allows this one part number to fit four different small block Chrysler engines. The damper without any weight fits internally...

professional-products.com

There you go.

 

[71scamp78]

that balancer looks bobo AF. super sus. i'd be replacing that with a known entity before chasing my *** on a whole host of other laundry list items.

Yeah think I'll buy a cheap stock one and see if that does it. Hate to pull trans if not needed

 

[junkyardhero]

Yeah think I'll buy a cheap stock one and see if that does it. Hate to pull trans if not needed

hear me out... anything worth a **** is gonna be about the same price. and at a chirp over 100 you get free shipping from the top of the mountain parts conglomerate online presence. the bonus here (besides the free shipping) is that you don't know what it's balanced to, so this having many modes may solve your problem if it's decidedly not the correct stock balance.

 

[71scamp78]

I got one with removable weights from summit

 

[71scamp78]

Well tried the new balancer today and it still has vibration but maybe ever so slightly less idk. took weight off and tried it and it was definitely worse. Not much left besides pulling the trans now ughhh

 

[PRH]

If you’re removing the flex plate, there should be a part number on it…….. then you can verify if it’s the correct one for a 360.
If it is, my suggestion would be see if there’s a converter company within a reasonable driving distance that has the capabilities of balancing(or checking the balance of) a converter.
Or you could try a different one.