PitStopUSA.com - Cylinder Hone Tools

Torque plates are bolted to the block deck while honing to simulate the stress applied to the bores when the heads are installed. If a cylinder is bored without a plate, once the head is installed, the bore will no longer be round at the top. Almost all factories routinely do this, as well as most engine shops. But torque plates allow an engine to break in faster, use less oil, and produce a little more power due to better ring sealing.