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5. A cylinder honing machine is used to give the cylinder bore a final size and finish. A boring bar is used as a rough cut, but a honing machine will finish the cylinder bore the last few thousandths of an inch. Lots of honing oil is used in combination with a stroking motion to put a nice cross-hatch pattern in the cylinder, which helps with ring seal and oil control. This block is being honed with a torque plate. The plate is bolted to the block to simulate the stresses put on the block by the cylinder head. If not used, then you may have a different shaped bore when the engine is actually running, which could cause irregular wear patterns.