I had a long post written about dyno testing and timing advance, and my web server dropped offline and ate it! Basically, I duplicated the findings my father got with chassis dyno runs of a dirt track racer with a flathead V8 and alcohol in the early 1950's with a series of water brake bellhousing dyno pulls on small block Chevy race engines 50-something years later. Both series of tests proved that one degree too much timing advance at full throttle robs as much power as 4-5 degrees of late timing at the same engine RPM and load. Once the "sweet spot" of maximum spark advance is found, any further advanced is trying to run the engine backwards.
Very cool that you have data (and history!) like that.
