007husky

What is the diference betwen an 8 inch harmonic balancer and a 6.75 one ?

My current balancer is missing chunks of ruber, parts of it is out , is at 8.2 inches or 8 somethign.

Is this stock ?
should i get a 6.75 one ?

Thanks !

PS: so if the balancer is not original, and the original timing mark was for a 6.75 ... would it take my timing about 10 degrees short, if timed with the original mark ?
and if so, is there any change than having the timing wrong, could create shaking avolve 3k rpms ?

FB007

1.25 inches.

You can use either one. Each uses it's own pointer.

kunkle

My current balancer is missing chunks of ruber, parts of it is out , is at 8.2 inches or 8 somethign.

and if so, is there any change than having the timing wrong,

Timing won't give you the shakes

could create shaking avolve 3k rpms ?[/QUOTE]

Let's see.....balancer missing "chunks and parts" and shakes above 3k rpm. I'm gonna go out on a limb here and bet the engine is gonna run a lot smoother with a balancer that's in one piece.

7T1vette

The different sized harmonic balancers are to be mated with specific engines. Their purpose is to cancel out the natural resonance vibrations that occur in any internal combustion engine. Some engines resonate at different frequencies and their amplitude is different than what other engines produce. While you may not notice significant differences between their use on some engines, your 'best' choice is to use what was specified for your engine. If you modify your engine you may [or may not] need to change the 'damper' to one that better matches it. It is not just a matter of using a larger damper for some engines than others.

007husky

Let's see.....balancer missing "chunks and parts" and shakes above 3k rpm. I'm gonna go out on a limb here and bet the engine is gonna run a lot smoother with a balancer that's in one piece. [/QUOTE]

I really hope so ! becouse i ve come to the balancer, clutch n plate or some internal unvalance and i dont want to touch the last 2 !

007husky

The trick is to know what they did to the engine or if the guy just found an 8 inch dampener and slaped it in there just becouse is what he had laying around.

Now i m wondering if i should get stock 6.75 or another 8.

stock76

You may find the information you need here; http://www.atiracing.com/products/dampers/index.htm or here; http://www.pro-race.com/faq.htm. If you aren't sure of the sizing necessary I'm sure either of these could help you if you call them.

If your damper is original to the car and you want to have it rebuilt this company can do it; http://www.damperdoctor.com/.

If your damper is missing chunks of rubber, the outer ring will probably slip soon, if it hasn't already, and you won't be able to set your timing. If the elastomeric ring fails completely the damper could come apart and take out your radiator or worse.

You'll need a removal tool and the install tool too.

FB007

I find this highly unlikely. I also belive that if GM did some sort of "average" reading for a decision, in a modified engine, the point would be moot.
Do you know of any articles to substantiate your claim?

RunningMan373

L48s used the 6.75" one, L82s used the 8" one. if your stock timing tab works with your present 8" one, that was probably stock to your engine. http://www.summitracing.com/parts/SUM-161358/

7T1vette

FB007...
While I can't answer your question directly, the webpage listed give you a look at how engines are analyzed to determine frequencies and amplitudes of vibration for a specific engine. That information is then used to design or choose a balancer that can absorb those amounts & frequencies of vibration.

http://www.dalemfg.com/dale_026.htm

If significant changes to the design of an engine are made...such as the amount of power it produces, the mass of rotating parts, the rpm range it is capable of achieving, modification of exhaust systems, etc....harmonic frequencies/amplitudes within the engine will be altered. I was just giving the poster a "heads up" that the balancer needs to matched to the vibration 'signature' of an engine, and that size is only one factor to consider in its selection.

007husky

Thanks !

I really hope this makes the vibrations./shakes go away.