The photo above shows an unmolested 340 small block. As pointed out by the arrows, some of the lifter bores are chamfered, or counter-bored. We do not know why Mother Mopar chose to do this. As you can see they are randomly bored to differing depths. The problem with this is that when you want to retrofit your block to a hydraulic roller cam the lifters that you need to use may come up high enough that the oil groove around the outer perimeter of lifter becomes exposed into this chamfer. This is not acceptable with most lifters. Our lifters address that problem by lowering the oil band.

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