I copied this link from an e-mail Jerdog sent to me that I thought was pretty interesting. Also, upon more research i have found that many engine builders have been complaining about how loose the chains have been fitting lately as opposed to years ago. I remember when I was putting timing chains on back in the day they were always very tight. Apparently that hasn't been the case as of late.
This is a pic of the Hy-Vo chain used in the NASCAR engines that are not running belt drives. I am currently trying to see if they make one for Chevy applications.