Fluid-Damper ??

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pastortom1

pastortom1

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On a new 273 rebuild (.30 over, very mild cam), the motor came back with a slight imbalance..... It COULD be that they used a new converter on my 904 with a counterweight....I have NOT verified this yet, but will shortly.....

My question is this: If the converter is neutral, and they used the stock balancer (also neutral), will a "Fluid-Dampr" take care of any remaining vibration due to a slight imbalance problem? (the vibration is evident at 'idle'....this is not a tranny to rear problem).
 
imbalance will not be corrected by a balancer. The weights are different and the harmonics would be what your trying to dampen with the fluid. There will be more harmonics then the fluid damper could handle - IMO
 
I believe the 273 to be internally balanced?,so no need for the weight on the 904 convertor(just grind it off)I,d just get a dampner for internal balanced engine.Cheaper than a pricey Fuid dampner.JMO.
 
I don't think so. It may help but the damper is made to take the harmonics out not sure it can cure an imbalance. I'm no xpert tho so I will be watching this post
 
I think you have the concept of a harmonic damper mixed up... Its purpose is to dampen torsional impulses on the crank caused by the forces of combustion on the pistons/rods; it sort of 'soaks up' the harsh rotational impact of the pistons/rods on the crank during the power stroke. Vibrations caused by imbalance of the crank counterweights and reciprocating assembly are something totally different and can only be fixed by properly balancing the internals or adding the appropriate counterweights to the damper/flexplate/converter.
 
Tried it didn't work. Thought I to could get away with it on a coustomers car when couldn't find a 360 balancer. You can cut the weights off the converter in the car with just removing the inspection cover. Be careful if you use a chisel .I did it already and tore a hole in the converter.
 
I've seen a few imbalance issues and none were ever present at idle. Not saying it can't be, just that it'd be odd. Does it vibrate at any other rpm? If not I doubt it's a imbalance problem. Maybe something as simple as a carb needing adjusted or a vacuum leak.
 
You can "idle" a car at 5000 rpm if you want to...........

The vibration is present when the car is not moving.

The question was, will a fluid damper HELP a noticeable vibration in a motor where the current balancer and converter are CORRECT for that motor.

We have one answer from his experience.......He states emphatically, "no".

Anyone else from experience? Tried this before?
 
While my answer wasnt from experience of trying to band aid a problem it was from extensive research on dampers I did when looking for one for my stroker motor. Read pages of literature on harmonics till I understood it. My best friends a machinist and we have had many discussions on motor vibrations on motors customers bring in. And idle is not 5k,it is generally the lowest rpm a motor will run cleanly. So let me change my answer to no. If everythings correct bob weight must be off and will need correcting to fix the problem. Did you rebalance for the new pistons or weigh them against one another?
 
I didn't rebuild the motor, and from what I can gather from the builder (which is sparse) he as much as admits that care was not taken to internally balance the 273, which it should have.

So, we have an internally balanced 273 that may or may not have been properly balanced........I have NO idea what crank he used either, or if he could have used an incorrect crank........he stated he had to look far and wide to find one for the 273.........

A Fluid-Damper came to mind since the internal gel seeks it's own balance, so to speak, as the motor rotates......it compensates against harmonics......My question arises since I don't know if such a Damper would HELP bring down the current harmonic vibrations.
 
pastortom1 said:
You can "idle" a car at 5000 rpm if you want to...........

Who in their right mind would idle a street car at 5000 rpm??
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The vibration is present when the car is not moving.

What makes you positive it's an out of balance issue? A misfire, whether due to an ignition or carburetor problem can make an engine vibrate!
Click to expand...

The question was, will a fluid damper HELP a noticeable vibration in a motor where the current balancer and converter are CORRECT for that motor.

We have one answer from his experience.......He states emphatically, "no".

Anyone else from experience? Tried this before?
Click to expand...

I haven't tried it but I'm sure that if an engine is out of balance a band-aid fix such as installing a fluid damper isn't going to fix it. Sorry I ruffled your feathers by trying to help. It won't happen again.
 
Fishy, I have no idea what you're talking about.......Neither you or anyone else responding "ruffled my feathers"...........From your last post it might seem like your feathers were afluff for some reason. We know it's a balance issue..........we've been over every other system on the car a dozen times and 24 on Sunday. The motor VIBRATES at varied RPM's, exactly as one does when the wrong balancer or converter is used.

I tried to state the question plain and simple.

As for the band-aid statement, that's the point isn't it? I asked whether or not such a device would HELP.......Point being, I DON'T KNOW.......I don't know if it's feasible, or if it's a "band-aid" as you call it.

When a counterweight is used on a balancer for external balance and the same on a converter, is that a band-aid for a motor that will vibrate without 'em? THAT point being that the weights FIX the problem (or design).

A Fluid-Damper seeks a "balance" for harmonics. Whether or not it would help in THIS situation was the question.
 
Anyone else from experience? Tried this before?
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The simple answer is NO, the fluid dampened will not help with vibration. harmonics, yes, vibration NO.

IF the vibration is in the internals of the 273, you COULD balance the converter and dampener to compensate, in other words, external balance an internal balanced motor.....

Small experience last summer.

My boat motor. Built a LA318, from the best junk in the garage, took the 360 flywheel to a machine shop to get it balanced, and they didn't balance it and said it was at zero.

The second the 318 was fired, the tools were moving across the deck. It was BAD. I suspect a weighted converter in a car would do the same thing.

But the simple answer.....

A Fluid-Damper seeks a "balance" for harmonics. Whether or not it would help in THIS situation was the question.
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Not a chance.
 
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