Variable Cam Stuff

[Gary Derian]

Another issue is that the torque on a cam is not consistent as it turns.  A
V-8 pushrod cam is not too bad but a cam for a DOHC 4 cyl  or V-6 really
jumps around as it turns.  A variable timing device needs to accommodate
that.  I think a simple friction or centrifugal device would not control
position well.
Gary Derian <gderian at cybergate.net>

-----Original Message-----
From: Frederic Breitwieser <frederic.breitwieser at xephic.dynip.com>
To: diy_efi at coulomb.eng.ohio-state.edu <diy_efi at coulomb.eng.ohio-state.edu>
Date: Wednesday, July 01, 1998 11:57 PM
Subject: Re: Variable Cam Stuff


>>I was thinking of using something similar to the centrepital advance
>>flyweights that are used on a mechanical distributer.  The biggest fly in
>>the ointment would be the large load that is on a camshaft.
>
>Howdy Ray.  I'm thinking aloud here, so don't take this as a fact.
>
>If you use centrifigual force to change the rotation of an object, you
>adjust its acceleration capability drastically.  Rotate a 10lb bowling ball
>upon an axis, then rotate a 2' wide 10lb dumbell, and you'll see what I
>mean.  The dumbell takes more effort to accelerate rotation (and more
>braking power to stop).
>
>That aside, if you have weights on your camshaft that can extend in and out
>towards the centerline of the rotational point of the camshaft, and you
>have equal weight all around, you won't load the camshaft bearings much, if
>at all (other than what gravity does).  As the weights extend, they'd be
>balanced by their sister weight 180 degrees out of phase.
>
>Just a thought.
>
>
>Frederic Breitwieser
>Bridgeport, CT 06606
>
>Homebrew Automotive Website:
>http://www.xephic.dynip.com/
>
>"When in doubt, use a bigger hammer"
>-