Should I gap my NGK iridium spark plugs?
In most cases, NGK iridium spark plugs are pre-gapped at the factory and should not be regapped. The correct gap depends on your engine, so you should follow the gap specified by the vehicle manufacturer or NGK for your exact plug model. If you cannot locate the spec, check the packaging or NGK’s official guidance. This article explains when gapping is necessary and how to do it safely if required.
Do NGK iridium plugs require gapping?
Before you decide whether to gap, it helps to understand if your plug model is designed to be shipped pre-gapped and whether your engine actually requires a different gap. The guidance from NGK and many auto manufacturers is to use the gap specified for your particular application and to avoid re-gapping unless explicitly directed. This section outlines the practical considerations.
- Check the plug packaging or the NGK product page for your exact model to confirm whether the plug is pre-gapped and what the intended gap is for your engine.
- Do not gap a plug that is labeled as "pre-gapped" or "no re-gapping required" unless the manufacturer explicitly instructs you to do so.
- If the engine manufacturer or NGK specifies a different gap for your application, adjust to that exact value using proper tools and care.
- Avoid gap adjustments on damaged or worn plugs, as regapping can compromise the electrode and sealing surfaces.
- If you are unsure or cannot locate the correct gap specification, replace the plug with a new one that matches the engine’s spec instead of attempting to re-gap.
Before starting the list, note that these guidelines help you decide if you should gap and what to check before touching the plug.
In summary, always start with the official gap specification for your plug and vehicle. If the plug is marketed as pre-gapped or if the manufacturer does not require gapping, do not attempt to change the gap.
How to gap an NGK iridium plug safely (if allowed by the spec)
If your specific NGK iridium plug or engine requires a gap beyond the factory setting, use these steps carefully to avoid damaging the plug or the engine.
- Confirm the target gap from the owner’s manual, vehicle service documentation, or NGK’s product page for your exact plug model.
- Gather proper tools: a spark plug gauge (feeler gauge), a soft brush or cloth for cleaning, and a torque wrench or spark plug socket for installation.
- Inspect the plug before gapping: look for cracks, chipped electrodes, or carbon buildup. Do not gap a damaged plug; replace it.
- Gapping process (if approved by the spec): hold the plug by the base and lightly bend the outer ground electrode to achieve the desired gap, using the gauge to measure accurately. Avoid applying force to the center electrode or prying aggressively on delicate parts.
- Re-check the gap after adjustment and ensure it is within the specified tolerance. Inspect the plug for any signs of stray metal shavings or damage.
- Install the plug using the manufacturer’s torque specification and, if recommended, use anti-seize compound on the threads. Recheck torque after installation if your service procedure requires it.
Following these steps helps minimize the risk of misfires, damaged electrodes, or poor sealing. If you are not confident in gapping or if the spec is unclear, seek professional assistance rather than risking engine damage.
Summary
Bottom line: for most NGK iridium plugs, you should not gap them unless the engine manufacturer or NGK explicitly requires a different gap. Always verify the exact gap specification for your plug model and engine from the packaging, NGK’s official site, or the owner’s manual. If in doubt, replace with a correctly gapped plug rather than attempting an unapproved adjustment. Proper installation and adherence to the specified gap help ensure optimal combustion and plug life.
