<VV> Re: [FC] [VV] Harmonic balancers....

[Roger Gault]

When I designed my 3.6L with the 1/2" additional stroke I "calculated" a new
natural frequency and had David L. at Dale Mfg. build me one with slightly
thicker rubber to match that frequency.

I am considerably disturbed to find that I cannot find any of my notes on
this, including any e-mails to/from David.  In particular, I cannot find my
natural frequency calculations (which were closer to guesses) - and, I'm
completely blank on the subject.  The only thing I remember is that the
damping frequency is inversely proportional to the cube of the rubber
thickness, so it doesn't take much change.

I think doing this change is pretty important on my engine, which is street
driven.  The resonance point of interest is at 4400 rpm on the stock crank.
Running a 3.55:1 rear end, that's only about 88 mph.  If the resonance drops
10% because of all the added stroke length (and in my case bigger pistons
and longer rods), that's getting uncomfortably close to highway speeds.  If
you're racing, you'd probably spend less time near this rpm, but the loads
are going to be higher.

Roger

PS:  It is conceivable that I just set the HB frequency to around 3500 rpm,
where my engine spends most of it's time, on the theory that I'd just try to
damp the driving frequency.  I can't believe I've forgotten all this in only
2.5 years.  What an idiot.


----- Original Message ----- 
From: <BobHelt at aol.com>
To: <ral1963 at comcast.net>; <noahsarkinc at earthlink.net>;
<krupross at sunwave.net>; <corvanatics at corvair.org>
Cc: <virtualvairs at corvair.org>
Sent: Saturday, June 30, 2007 1:22 PM
Subject: Re: <VV> Re: [FC] [VV] Harmonic balancers....


<snip>

> Most likely you will require a new HD based on the new crankshaft. The
stock
> HD is likely insufficient to protect the stroked 8409 crank.
>
> Regards,
> Bob Helt