The round holes machined into the block for the pistons travel up and down in are called:

The round holes machined into the block for the pistons travel up and down in are called:

• A. Valve seats
• B. Cam tunnels
• C. Cylinder Bores
• D. Piston pin bosses

Answer: (C)

Cylinder bores are the round holes in the engine block that the pistons move up and down in. They form the cylindrical walls that contain the piston as it compresses the air-fuel charge and converts it into mechanical work. The bore size and condition affect compression, oil sealing, and overall engine displacement, and some engines use sleeves or liners inside the bore. Valves don’t sit in the block holes for pistons; they seal in the cylinder head. Those seats are where intake and exhaust valves close. Cam tunnels are passages that route the camshaft or timing components, not the piston paths. Piston pin bosses are features on the piston itself where the wrist pin attaches, not holes in the block.

Cylinder bores are the round holes in the engine block that the pistons move up and down in. They form the cylindrical walls that contain the piston as it compresses the air-fuel charge and converts it into mechanical work. The bore size and condition affect compression, oil sealing, and overall engine displacement, and some engines use sleeves or liners inside the bore.

Valves don’t sit in the block holes for pistons; they seal in the cylinder head. Those seats are where intake and exhaust valves close. Cam tunnels are passages that route the camshaft or timing components, not the piston paths. Piston pin bosses are features on the piston itself where the wrist pin attaches, not holes in the block.