[Land-speed] Bad vibes

[Rich Fox]

My and other GMC inline six cylinder engines were pretty good at doing the
same thing. Mine seemed to want to weld to the flywheel at the drags. Not at
Bonneville. I could only guess that the rate of acceleration somehow caused
the crank to flex more that when the RPM came up more slowly on the salt.
From: Neil Albaugh <neil at dbelltech.com>
To: LSR LSR
<land-speed at autox.team.net>; Don McMeekin <landspeed at columbus.rr.com>
Sent:
Monday, May 30, 2011 9:22 PM
Subject: Re: [Land-speed] Bad vibes

Don;

Back
when JW/Gulf Racing was running the Ford GT40 Le Mans program, they used a
Cosworth V8 with a 180 degree crank. The first few laps at a test track were
run and the driver brought the car into the pit. In answer to the question
"How many RPM were you turning?", the driver simply pointed to the tach-- the
needle has shaken loose and was lying at the bottom of the glass. All the
other instruments were in the same sorry state. The vibration was so severe
that something broke almost every time the car was run.

An in-line 6 is
inherently in balance but an in-line 4 is not. You have your work cut out for
you.

Regards, Neil  Tucson, AZ
--------------------------------------------------
From: "Don McMeekin"
<landspeed at columbus.rr.com>
Sent: Monday, May 30, 2011 8:03 PM
To: "LSR LSR"
<land-speed at autox.team.net>
Subject: [Land-speed] Bad vibes

> Anyone silly
enough to cut an engine in half should probably expect  to encounter some
"unusual" problems along the way. During a recent  dyno pull, our half Windsor
(3 liter inline four) sheared off all six  Locktite secured 7/16" ARP flywheel
bolts, and almost welded the  flywheel to the crank. Seems that we have a
harmonic vibration  problem that has created more force than our system can
tolerate.  So.......... we probably need to strengthen the parts and reduce
the  "bad vibes".
> 
> The most obvious action would be to strengthen the
parts by  increasing the bolt diameter, adding some dowels, and making sure 
that everything fits. Reducing the the force could be a little more 
difficult.  The balancer (cheapo fluid type) is clearly not up to the  task
and should to be upgraded to something more in tune with this  engine's
harmonic characteristics.  I really don't have any  experience in this area
and would  greatly appreciate any thoughts  that list members would care to
share.
> 
>                  Thanks, Don
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