Porsche 356 Spark Plugs

How to inspect, gap, and install spark plugs on a 356 engine — and what they tell you when you pull them.

A spark plug change is a ten-minute job. But pulling four plugs and reading them in cylinder order gives you more information about the condition of each cylinder than almost any other ten minutes you can spend on the engine. Colors and deposits tell you whether a cylinder is running rich or lean, burning oil, or misfiring — and which one. That diagnostic value is the main reason to pull plugs at every oil change, not just when they need replacing.

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