The crank angle sensor runs off the crank pulley, and its starting to slip (my base timing changes slowly after time). While not exactly the same, picture teeth on the outside of the blue disc in this picture:
The teeth are rotating in relation to the crank.
So I pop on Flyin Miata for something else, and run across this:
http://www.flyinmiata.com/index.php?dep ... %201991-95
Now at this point in my automotive career, I've seen the straight underdrive billet pulleys (undamped), and also know that damn near all OEMs have a pulley with a damper in it, so there must be a reason. I also wondered why a higher horsepower engine would require a better damper (not including a supercharger- something that puts more load on the crank pulley). I thought "the crank pulley shouldn't care... it just sees spin. It shouldn't care if its in neutral or 6th gear".
This handy-dandy article explains things really well:
http://www.atiracing.com/products/dampers/101/index.htm
and http://www.atiracing.com/products/dampe ... _dinan.htm
Essentially, under higher horsepower applications, the crank becomes a torsion spring. It "twists" elastically, and the crank pulley helps to dampen those spring oscillations.
