Variable cam timing

[jfaubion]

>ehernan3 at ford.com (Edward Hernandez (R)) Wrote: | 
     
>I remember a mechanical type described in Motor Trend a while back.  The 
>chain end of the camshaft was threaded, and the sprocket screwed onto the 
>thread.  There was an oil driven piston that pressed against the sprocket.  
>As the piston moved the sprocket back and forth, it caused the camshaft to 
>be advanced or retarded via the threads.  It was a very coarse thread.

<SNIP>

This would change only the timing, not the shape of the lobe. Controlling 
the lift and duration of the valve would change the performance much more 
dramatically. Why not use a solenoid valve to bleed off pressure from 
hydraulic lifters? The cam could be ground much more radical and the 
computer could easily bleed off the difference.

My real preference would be solenoid actuation of the valves but I believe 
that to be a few years away. Does anyone know of any projects doing this? 

John Faubion
jfaubion at cs-smtp.tyndall.af.mil