The 91 octane gas we used was the last five gallons in the station's tank - probably about the worst 91 octane you would ever find.

Since this is a 80-90% street engine I did a fair amount of "cruise" testing on the dyno with the vacuum advance hooked up. The engine is set to 2500-3000 rpm and about 100-150 ft lbs and run to check cruise condition A/F ratio (LM-1) and egts.

With the total advance + vacuum advance set to about 45 I didn't hear any knocking. At 55 total+ vacuum it seemed there was some light knocking.

It will be interesting to see how it runs in the car, unhooking the vacuum advance is always an option.