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adjustable cam timing

To: Scions of Lucas <british-cars@autox.team.net>
Subject: adjustable cam timing
From: Greg Meboe <meboe@wsuaix.csc.wsu.edu>
Date: Fri, 12 Aug 1994 11:46:59 -31702 (PDT)
        Fellow SOL'ers, 
  This discussion about adjustable cam timing has got me rethinking an
old modification that I had planned, but then put on the back burner.
  If it would be desirable to have different cam timing setups for 
different types of events, then there should be a way to quickly change cam 
timing, similar to the way we can change ignition timing for different 
octane levels.
  Here's how it would work.  (I'm not Marcus so I won't even attempt a 
cool ASCII drawing.)  On the tense side of the chain, (driver's side), 
install a very small idler sprocket in the middle of the chain's travel 
between the crank and cam sprockets.  This sprocket would 'push' into the 
chain from the outside, effectively advancing the relationship of the cam 
sprocket to the crank sprocket.  Adjustment would be provided by an Allen 
stud, threading into the side of the timing chain cover.  The Allen stud 
would be held fast by an outside nut.  
  The slack taken up by the adjuster would be compensated for by the tension
spring on the 'loose' side of the chain, as currently exists.
  'Zero' could be achieved at the center of the adjuster's travel by 
using an offset key, or Zero could be set wherever convenient for the 
particular engine.  
        My question: has anyone seen this idea, or thought of it themselves?
I think this would be an effective modification for easily changing cam 
timing, or it would at least add enough complexity to cause it to become 
unreliable, like the rest of the car.

    What do you think?
                              Greg Meboe    meboe@wsuvm1.csc.wsu.edu



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