After servicing spark plugs from an opposed engine, how should they be reinstalled?

The best approach to reinstalling spark plugs after servicing them from an opposed engine is to place them back in the original position that they were removed from. Each spark plug in an engine is designed to fit into its specific cylinder, and reinstalling them incorrectly could lead to uneven engine performance or potential damage.

Reinstalling a spark plug in the same position it was originally located ensures that there is consistent wear and a proper fit, preventing potential ignition issues. The orientation and position of spark plugs can also influence combustion efficiency and engine timing, making it critical to maintain the original configuration.

Choosing to install spark plugs based on firing order or switching them bottom to top could disrupt the synchronization needed for optimal engine operation, while a size preference is irrelevant as the plugs are uniquely designed for their respective positions in the engine. Therefore, reinstalling them in the original position is paramount for maintaining the reliability and functionality of the engine.