Final answer:
Excessive bearing clearance is the least likely cause of cam bind because it allows more room for the camshaft to move, unlike the other conditions that disrupt its smooth rotation.
Step-by-step explanation:
The question posed pertains to issues that can lead to cam bind, which is a condition in engine mechanics where the camshaft has difficulty turning within its housing. The least likely cause of cam bind out of the options provided would be excessive bearing clearance. When there is excessive clearance, the camshaft would have more room to move, not less, which would typically prevent binding. The other three issues mentioned – excessive runout, improperly installed cam bearings, and bore misalignment – could more realistically result in the camshaft binding because they each represent conditions that disrupt the smooth rotation of the camshaft within the engine block.