Virtually all NGK spark plugs are set to the correct gap for the catalogue applications at the point of manufacture'. Reactions: losh1971, Tonner Matt and immortality. Excessive spark plug gap results when the voltage has too far to travel. All engine manufacturers publish specifications for spark plug gap in owner's manuals and online. What is my lawn mower spark plug gap? Spark plugs with the gap set too small on them can make the motor run poorly. Getting the best gap between the points is essential for proper engine performance and reliability. If you have no spark and your trigger tests ok, your stator tests ok and you have tried a new set of coils then we’re possibly looking at a bad CDI box. Spark plug gap too small? If so you can lift the side electrode with a pliers. Does the OE require iridium plugs? The next step is to measure the spark plug gap. A spark plug gap is the distance between the end of the electrode and the base of the spark plug. Corroded spark plugs can often be cleaned. A narrow gap may give too small and weak a spark to effectively ignite the fuel-air mixture, but the plug will almost always fire on each cycle. Check the gap on all spark plugs, even ones that claim to be pre-gapped. too small might run oddly, but too large will fail to spark at high load, which does really interesting(bad) things to your secondary ignition, along with falsely triggering the knock sensor most of the time. Do all spark plugs … Increase or decrease the size of the gap as needed based on engine manufacturer recommendations. A fully-functioning spark plug helps burn fuel efficiently in the combustion cycle. Replacing the spark plugs will do the trick as well. The specified spark plug gap is 1.0mm. Just a suggestion to inspect the spark plug and verify that the center electrode is not making contact with the side electrode as they need to have a small gap in between. Set the points too wide and the spark plugs don't get enough juice. Set them too close and the engine works fine for a few miles… until the points are burnt beyond use. Discussion Starter • #1 • Jan 7, 2011. will a spark plug gap that is too narrow cause the engine to misfire? If the tool does not touch the electrodes at the appropriate measurement, the gap is too large. It may be convenient to have an extra spark plug handy so you can try replacing the plug altogether to be sure if a faulty spark plug is causing the engine to misfire. Understand how the gap affects engine performance. If they’re too loose, you may be able to turn it with your fingers. But that’s just some basic fitment info, many companies offer different types of plugs, so you’ll have to do some research to see if you’ll have any benefits beyond a stock plug. When spark plugs are replaced, the gap is checked and altered if necessary. The surest way is to inspect and handle them directly, as discussed in depth in our guide to spark plug diagnosis. The spark plugs fire up your cylinders, and they can get worn over time. However, when the garage fitted new plugs (champion copper core/electrode), they didn't adjust their gap and left them at 0.8mm. Use a ramp-style gauge when necessary. If the gap is too large, the plug may not fire at all. Too tight, and it won’t budge at all, even with a wrench. It is important to know the least amount to gap the spark plugs as well as the greatest. Too small, and they can get lodged into the seams of the spark plug." Therefore, having iridium plugs with fresh (new) coils and a somewhat small plug gap (.039) is more than adequate for a stock engine. Spark plugs are often very cheap and, in most cases, easy to replace. Decreasing the gap can make it vulnerable to incomplete burn or misfire. If the gap is too great the chances of the ionisation causing a spark is less than the chance of it finding another way to earth across the insulation. If the gap is too wide the ignition system components are required to work harder to jump across the extended gap leading to spark plug, ignition coil, and control module failures. When a engine has forced induction, aka *(turbocharger,supercharger or blower) it increases the cylinder pressure and can cause the spark to blow out when the spark plug gap is too big. The gap is pre-determined by the manufacturer and it is measured in millimeters.