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Grinding Stone

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The best way to overbore an engine isn’t by hand with an inexpensive tool, but we started this rebuild with budget in mind. The best way is to drop the block off at the machine shop and let ’em rip. The next best way would have been to use a coarse stone to knock the ridges down and then a finer stone to clean it all up once we were within 0.003-inch of our 3.780-inch goal. However, as of this writing, the Performance Tool abrasives are only available in 220-grit. We’d rather have had 150-grit or so to knock the ridges down and 300-grit or finer for the finish. We used Rapid Tap cutting oil to lubricate and cool the stones, but engine oil also works in a pinch. We turned the pre-load up at the beginning to knock the ridges down and dialed it back down later.