About 8 hours to be exact. I had a almost new set of BB's that I pulled from a blown E350 a while back, My truck had fairly new injectors that I had already pressure matched but I decided to set these up.. I set them all at 1950 They are no more than 5 lbs either way, It was really tedious and very time consuming.. But my truck has never idled smoother, Feel's like it may have picked up a few horses.. But the smoothness throughout the powerband is very noticeable. And yes I did reset the timing afterwards.. The last set was set between 1825 and 1875. To me it was definitely worth the time.