What is my lawn mower spark plug gap? Gap new as well as old spark plugs… Symptoms: Rounded electrodes with a small amount of deposits of the firing end. In most cases your Iridium Power plugs do not need to be gapped. A spark plug is a fairly simple device. Adjusting the distance between the two electrodes is called gapping your spark plugs. However, if the spark plug gap is too large, the spark is unlikely to consistently "jump" across the long distance between electrodes, thus leading to a rough-running engine or one that doesn't run at all. Normal colour. Even with small variations in the factory set gap the ultra-efficient firing power design will compensate for those small variations. Most of … If too large spark won't be able to jump gap … The electricity must be at a very high voltage in order to travel across the gap and create a good spark. The spark plug must be in good condition and must be properly gapped for proper engine performance. Appearance & Symptoms: A plug with a combination of erosion, corrosion, and oxidation will have pitted and rough electrodes and may even have a green cast if the oxidation is heavy. Too small of a gap and the electrodes themselves will have an increased likelihood of quenching the very small initial burn, known as the flame kernel. Causes hard starting in damp or cold weather and poor fuel economy. If the gap is too small, the spark will likely be too weak and cause the engine to run poorly or with poor efficiency. If the gap is too small, the mower may not be able to spark at all. This can result in engine hesitation. If the gap is too small, ... a Haynes Manual which will have this diagram in it as well as the correct spark plug gap and you may also find a spark plug gap tool too. Follow the recommended maintenance schedule. The spark plug is quite simple in theory: It forces electricity to arc across a gap, just like a bolt of lightning. To increase the gap, gently bend the ground electrode towards the center electrode. The gap must be a specific width if the gap is too small the spark doesn’t have enough space to generate the power needed to ignite the fuel. To gap a spark plug, use a coin-style or blade-style gap tool to measure the gap between the electrode tips. A gap that is too small will cause a low firing voltage resulting in incomplete combustion. The size of the gap affects the spark plug's firing temperature which in turn is related to the combustion of air and fuel in the engine. You need a feeler gauge to gap your spark plugs properly. If the gauge has a lot of room to wiggle around, your old plug may have worn down its center electrode, causing a gap that’s too large. These conditions can result in increased, improper spark plug gap and yield poorer performance. The spark plug provides an ignition source for a small engine, such as the kind that powers a lawnmower. That is only .04 just be sure you know proper way to use gap gauge so you get them set right or car won't fire properly. Noticed that the rebuilders (who had put in new plugs) left the WR7DC Bosch plugs with too wide a gap (.036", which is how they come out of the box) instead of regapping to the correct 0.028-0.032" gap. It can also cause a loss of top-end power. Unfortunately, that plug may have hundreds of applications from automobiles to golf carts. Spark plugs MUST be gapped before installing in the engine. An engine that hesitates, or stumbles, upon acceleration is often the result of incorrectly gapped spark plugs. Appearance & Symptoms: A plug with a combination of erosion, corrosion, and oxidation will have pitted and rough electrodes and may even have a green cast if the oxidation is heavy. Setting the gap for your particular engine is important as insufficient spark plug gap can cause pre-ignition, detonation and even engine damage. A wet spark plug can indicate water in the fuel while a white residue on the plug can point to a plug that is too hot. The act of setting this distance correctly is commonly referred to as "gapping" your plugs. Worn Symptoms: Rounded electrodes with a small amount of deposits of the firing end. If you can't fit it between the electrodes, the gap is too small … Recommendations: When new spark plugs are installed, replace with plugs of the same heat range. If the tool passes through the gap without touching the electrodes at the appropriate measure, your gap is too wide. Too narrow a plug gap can cause a RICH running condition, incomplete burn of fuel, and potentially carbon buildup. Even iridium plugs! Worst case, this would result in a complete misfire. To gap a spark plug, use a coin-style or blade-style gap tool to measure the gap between the electrode tips. What do spark plugs do. A normal spark plug will appear dry with a grayish color. Ignition cables deliver high-voltage current from the ignition coil to the spark plugs on older engines fitted with distributors. Step 4: Adjust the spark plug gap. Just got through replacing spark plugs for the first time since top end rebuilt two years ago. You’ll need to go to the manufacturer’s website or read the manual to see the exact gap of your lawnmowers spark plug. Although the engine will still run if one of the wires between the distributor and the plugs produces an intermittent fault, it will deliver less power or die altogether if the wire leading from the coil to the center of the distributor goes bad.