Harmonic Damper Required?
 

On our EG33's, is a harmonic crank damper required, or can we get away with using a simple aluminum crank pulley? On all other cars I've owned, I've always run high quality harmonic dampers from ATI. I'm just new to these Flat 6 engines, and have read how they are inherently balanced. Just wondering if this eliminates the need for a harmonic damper?

Re: Harmonic Damper Required?
 

You can just use a 1 piece pulley.

Re: Harmonic Damper Required?
 

The point of the dampner is to dampen engine vibration. If that doesn't concern you, you can replace it with a lightweight one piece unit. Don't expect any measurable performance increase, though.

Re: Harmonic Damper Required?
 

I was forwarded to this site. Its a good read on the Flat 6 Corvair harmonic balancer requirements.

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

Re: Harmonic Damper Required?
 

Its the torsional harmonics that move up and down the shaft, that can cause it to crack. If the engine ran most of the time at the same rpm, and there was a strong torsional offset at those RPM it will break.

The harmonic balancer is used to dampen or reduce these strong torsional offsets.

As the Corvair article also mentions is the affects these torsional offsets do the crank timing for spark, and the valve timing for the rear cylinders.

Harvey.

Re: Harmonic Damper Required?
 

It is suggested that the torsional vibrations involved are transmitted to the camshafts and valve gear. All of this is driven by a long flexible belt and has inherent self induced torsional loading problems, far exceeding anything possibly transferred from the crankshaft. There will not be any attributable effect on ignition, or valve timing, much less that confined to the rear cylinders.

A very strange document allegedly from GM with attached text, which refers particularly to making up a special grade of rubber for the Corvair. The publisher is Dale Manufacturing, Salem, Oregon. This data should be treated as simply advertising blurb, which demonstrates how fallible this stuff can be, and is particularly unsuitable as a learning text.

There is no mention of a very important factor involved, i.e. the load driven by the pulley via a belt, which is in itself an efficient flexible coupling. The weight of the outer portion of the pulley is insignificant as a torsional load, when compared with the total reciprocating weight driving the centre section. The driven parasitic accessories, therefore form the required major torsional resistance.