I´d all but guarantee he was off the clutch within 20 ft. You´re talking a final drive of 10.14:1, assuming a 3.73 R&P, with 33´s. That´s what caused it to slip. Not having the power it takes to truly slip one is the reason it eventually grabbed. Had it happen to me a few times when I was going through growing pains of finding the right gear/clutch combo without going overkill years ago. My final was 10.76:1 which is still a far cry from what he was trying to run. He tried to run hero gear and it didn´t work out. He obviously learned his lesson since he´s stepping down two gears for this next run. End of story. Now let us know how it turns out with a little RPM down the track and no more slipping the clutch, ...if there´s enough left to get you off the line.