With the RO7 block, the water jackets are completely redesigned compared to the classic small-block to help even out the temps from one cylinder to the next. Water flows into the cylinder head from the large hole at the 5 o'clock position at each cylinder. It then flows across the top of the combustion chambers before exiting the engine. The two large rectangular holes at the top of each cylinder also expose the water jackets, but the amount of water that can come out of these holes is restricted by the head gaskets. Also notice the extra holes for head studs. This not only helps improve head sealing but the holes also extend deeper into the block before the threads start to minimize cylinder bore distortion when the heads are torqued into place.