Testing the HiRev 7500

Bill Jones posted some of his tests of timing retard in this thread.
He's calling it hysterisis. The phenomenon is the same even if at that point he didn't know the full cause.
https://www.speed-talk.com/forum/viewtopic.php?f=1&t=22331
And here in the middle of hte page he describes how the factory (GM) compensated for slew in the distributor.
https://www.speed-talk.com/forum/viewtopic.php?t=22643&start=15
More discussions on slew.
https://www.speed-talk.com/forum/viewtopic.php?t=14367
and this one with some of the 'retard built in' history bubbling into the light.
https://www.speed-talk.com/forum/viewtopic.php?t=36678