The factory Dauntless bore is 3.750 inches and by the time we had all the ridges ground down the number three cylinder was at 3.770 inches (thanks to the broken ring). So we decided to go with a 0.030-inch overbore. Using the bore gauge from the rebuilder’s kit we were able to come up with the measurement. After boring a cylinder, it is possible that the cylinder walls aren’t parallel. That can lead to all kinds of nastiness from oil blow-by to busted rings. Much like our old high-school shop teacher would say, “Measure twice, cut once.” Don’t just go whole-hog with the boring tool, take your time and measure. Also, don’t measure just one spot in the cylinder. Measure the top, bottom, and center as well as a couple of spots in between.