Variable cam timing

[Kenneth C. King]

On Mon, 6 May 1996, Bruno! wrote:
> Hi everyone,
> I've been thinking about the subject of variable cam timing, which seems
> to come and go on this group. The idea of electromagnetically actuated
> valves may be prohibitive in the amount of power it would use from the
> electrical system, what about a synchro-type system where the amount of
> slip between the driving motor (driven from the crank) and the driven
> motor (connected to the timing chain / cam gear itself) can be varied,
> giving a variable cam timing technique? it could be extended into having
> different timing for intake & exhaust, for dohc engines. 
greetings:
  what i have been thinking about sounds fairly doable.  add a link (to
lengthen) the timing chain.  add a pair of idlers (pushing in, one spring 
on both of them) and mount both of them on a movable base.  this base can
be moved by oil pressure, centripital (spin, like timing) or electrical.
  to get the variable timing, just  
slide the base to one side (making the         (cam)        (cam)
one idler take up all the slack) to get        |  /          \  |
more timing, and run it the other to          o| |o -idlers- o| |o
retard it.  normal operation might be          ()/            \()
in the middle... (start retarded, for         crank          crank
more torque down low, thru the middle
to advanced for high rpm horsepower).  note that the ascii drawing shows
the crank cog moving side to side.  i claim artistic license. :)
  so, what do y'all think?  how much advance/retard could one get, and how
would such a timing adjustment change what kind of grind one selected?
later,
kc
--
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