The deck of the cylinder block is identified as the top portion of the bore where the cylinder heads bolt on. It is common for this surface to develop irregularities over time and heat cycling. These irregularities can lead to a loss of compression, coolant leaks, and head gasket failure. The term "decking" refers to the cutting and leveling of this critical surface. This is done to create an absolutely flat surface for the head gasket and cylinder head to mount upon. The flat surface must also be parallel to the centerline of the crankshaft, and at the correct angle relative to the bores. This procedure is also used to ensure the surface of the deck is the same distance from the crankshaft centerline on each bore. It may also be a method of adjusting compression ratio or decreasing the squish area. When material is removed from the block on a "V" design engine, both cylinder heads will be closer to the crankshaft, which can cause intake manifold fit problems. This can lead to other forms of corrective machining that will be covered later in the series.