Engine construction
The base of an engine is engine block, that contains crankshaft, pistons and connecting rods.
On top of engine block is cylinder head or heads, usually if it is bigger engine than 4 cylinders. Cylinder heads contain valve mechanism. Engine block is the body for an engine and all that is needed for engine to work is attached to it. Engine block can be a part of tractor's frame. Block and cylinder heads have both lubrication and cooling channels inside.
On top of engine block is cylinder head or heads, usually if it is bigger engine than 4 cylinders. Cylinder heads contain valve mechanism. Engine block is the body for an engine and all that is needed for engine to work is attached to it. Engine block can be a part of tractor's frame. Block and cylinder heads have both lubrication and cooling channels inside.