Spark plugs ignite the air/fuel mixture in your engine’s cylinders. A correctly gapped spark plug is crucial for optimal engine performance and fuel efficiency. This guide outlines how to accurately close the gap on a spark plug.
Measuring the Spark Plug Gap
Before adjusting, you need to know the current gap. This requires a gap gauge or feeler gauge.
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Clean the Spark Plug: Ensure the spark plug is clean, especially the contact points. Use a non-abrasive cleaner if necessary. Avoid harsh materials that could damage the plug.
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Use the Gauge: Insert the appropriately sized blade of your gap gauge or feeler gauge between the spark plug’s electrodes. The gauge should slide through with slight resistance. Note the measurement.
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Consult Your Manual: Compare your measurement to the recommended gap specified in your vehicle’s owner’s manual. This is crucial as gap specifications vary between engines.
Adjusting the Spark Plug Gap
If the gap doesn’t match the recommended setting, it needs adjustment.
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Select the Correct Gauge: Choose the gauge blade that matches the desired gap. This serves as your guide during the adjustment process.
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Adjusting the Gap: Carefully bend the ground electrode (the side electrode) using a spark plug gapping tool. Bend it inwards to narrow the gap and outwards to widen it. Apply gentle pressure to avoid damaging the plug. Important: Avoid contact with the center electrode, especially on plugs with precious metal tips (iridium or platinum) as they are fragile.
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Re-Measure and Repeat: After each adjustment, re-measure the gap. Repeat the process until the correct gap is achieved. The feeler gauge should slide through with slight drag.
Verifying the Gap
Final verification ensures accuracy.
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Final Check: Slide the correct feeler gauge blade between the electrodes one last time. It should fit snugly without excessive force.
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Consequences of Incorrect Gap: An incorrect gap can lead to misfires, reduced engine power, poor fuel economy, and increased emissions. Ensuring the correct gap is vital for proper engine function.
