What is the acceptable timing deviation for a vehicle with a specification of 12°BTDC?

For a vehicle with a specification of 12° BTDC (Before Top Dead Center), the acceptable timing deviation is typically set to ensure optimal engine performance and emissions control. The correct response indicates that the ignition timing must be within +/- 3° from the OEM (Original Equipment Manufacturer) specifications.

Staying within this tighter tolerance helps maintain the engine’s efficiency and minimizes harmful emissions, as ignition timing that is too far from the specified range can lead to issues such as reduced fuel economy, engine misfires, or increased pollutants.

In contrast, the other potential answers suggest broader tolerances or exact specifications that are not aligned with standard industry practices. Maintaining such precise control over timing is crucial for performance and compliance with emission standards, thereby justifying why a deviation of +/- 3° is essential for vehicles with a specification of 12° BTDC.