To pass inspection, the base ignition timing must be within:

When it comes to passing smog inspections, maintaining proper ignition timing is crucial for optimal engine performance and emissions control. The correct answer indicates that the base ignition timing must be within 3 degrees of the manufacturer's specifications. This tolerance level is critical because even slight deviations can lead to incomplete combustion, increased emissions, and potential failures in meeting smog standards.

Ignition timing that is set too far advanced or retarded can adversely affect engine efficiency. If the timing is too advanced, it can lead to knocking or pinging, which not only harms engine components but can also significantly increase hydrocarbons and nitrogen oxides in the emissions. Conversely, if the timing is too retarded, it can result in poor combustion, leading to an increase in carbon monoxide and unburned fuel emissions.

The specified range of 3 degrees allows for some mechanical variations and natural wear in engine components while still ensuring that the engine operates as intended. This range helps ensure compliance with emissions regulations while promoting engine efficiency and longevity. Understanding this tolerance is essential for technicians to effectively assess ignition timing during inspections and repairs.