harmonic balancer question

[gmcman]

This may be a noob question or a stupid one but I was wondering if anyone could explain what and how a harmonic balancer does? Is it just a flywheel for momemtum or does it absorb some shock from each power stroke to smooth power output?? Or what? I have read some other threads and discovered you can not swap balancers from other size engines or something like that.I have never fully understood this device and was hoping someone could explain this to me. Thanks so much!!

 

[lectric80]

Basically they are a tuned vibration dampener. As each power stroke occurs, the crank twists producing a harmonic vibration, the dampener cancels that out by twisting a large metal weight on a rubber dampener.

They cannot be moved between engines because they are really tuned and designed for the vibrations in the specific engine they are mounted on. So, a balancer designed to handle a 350 is going to react to harmonics for a 350. A 400 would have different harmonics, so it's balancer has to be tuned for it.

 

[MaxPF]

You can get a good explanation here.