Effects: Misfiring, loss of power, and potential engine damage. Your engine builder should be able to guide you in the right direction, but it's not hard to find out for yourself. When testing, be careful not to start with a hot plug. However, if the spark plug stays too hot, it becomes a sort of "glow plug" and can ignite the fuel mixture prematurely. At this temperature range, the plug becomes self cleaning and burns off any carbon buildup. Ash BuildupHeavy ash buildup on the insulator nose can clog the gap between the center electrode and the ground electrode. We have found that NGK makes the best plugs for Hondas, and we use them exclusively. 2002-2005 Subaru WRX Heads: Iridiums: Stock heat range: NGK – PFR6G You generally want to use a plug that's as hot as possible without causing detonation. This is commonly felt as a misfire during wide open throttle, and can be cured by gapping down. Spark plugs of a heat range "too cold" can appear black and "sooty," while spark plugs of a heat range "too hot" will cause detonation and the center electrode can look white, brittle, and/or pitted. If you read many automotive magazines, you've probably already seen an entire article devoted to plug indexing and how important it is in making power. Possibly change the brand of engine oil. Effects: Misfiring, particularly during acceleration (because the ignition voltage is no longer sufficient for the large electrode gap). Move up one heat range at a time until the plug stops fouling and is covered in a thin gray covering after a long run. Cause: Overheating caused by auto-ignition, for instance the ignition being too far advanced, combustion deposits in the combustion chamber, defective ignition distributor, or poor-quality fuel. We offer a service to pre-gap your plugs to 0.9mm which is recommended for tuned applications. Available in 14mm and 12mm plug thread sizes. Check the plugs to make sure they're not worn and the gap is correct. To change the gap just tap the plug on a hard surface, the cement driveway, etc. When more air is between the spark plug electrodes, it requires more voltage to jump the gap. If the misfire increases and/or you see little "lighting flashes" around the plug wires, the wires should be replaced or upgraded. Remove the spark plug-wire cap from the plug by hand. Loosen and remove the spark plug from the cylinder head with a spark plug wrench. Decades of testing have proven: if the ignition system is sufficient and working properly, gains from the latest whiz-bang spark plugs, fat wires, and high-powered ignition systems will be minimal. The sexy aspects of modifying cars are focused on the first two elements: Double Pumper carburetors, sophisticated fuel injection systems, whistling turbochargers, and massive blowers all work to cram more fuel and oxygen into our engines. Lead FoulingInsulator nose covered in places with brown/yellow glazing, which can have a greenish color. The heat of combustion warms the spark plug tip, and a plug with a long, insulated path back to the cylinder head has a hotter center electrode than that of a shorter, more direct path. Use a spark plug socket (13/16″) and ratchet to remove the spark plug and inspect the ceramic insulator. Cause: The spark plug extended too far into the combustion chamber and made contact with the piston. 100HP Over Stock = 1 Step Colder Plugs. A new Polaris Snowmobile Performance spark Plug is an easy-to-install part and will make your Sled better than before. More Boost = Less Gap. Effects: At high loads, the glazing becomes conductive and causes misfiring. We'll show you examples to better understand what's going on with your plugs. This is important in older, stock engines because it helps make up for inefficient combustion chamber and port designs. Not only can the correct plug choice help your engine run efficiently, spark plugs are also a fantastic diagnostic tool. Racing plugs have been the best way to make the engine more efficient, and this revolutionary Sled High intention spark plug is no different. If you start with a set of plugs that are too hot, you can potentially melt an electrode and drop plug fragments into the cylinder, which can hang a valve open or score the cylinder walls. A hot plug uses a large insulator nose area to absorb heat from the combustion process and hold it, while a cold plug has a smaller insulator area and is designed to dissipate the heat absorbed from combustion into the head and cooling system. A worn spark plug not only wastes fuel but also strains the whole ignition system because the expanded gap (due to erosion) requires higher voltages. You want a full turn of light soot color on the base ring!!! Your information will be collected and used in accordance with our  Privacy Policy. Remedy: Fit new spark plugs. I've read on this forum to not re-gap the the new plugs unless they got moved during shipping. If you want to tune for max. Melted ElectrodeCenter electrode is melted and ground electrode is severely damaged. Regardless of what it is or where it came from, there is going to be carbon buildup in the combustion chamber over time. If it's too cold, carbon will be allowed to build up until it fouls the plug. Here's a trick: in a dark place, open the hood with the engine running. Recall that air is an insulator (doesn't conduct electricity well). Your choice in plug selection features different “heat range” spark plugs. The spark plug heat range may also be too low. Of course, it's not as easy as going to the parts store and picking up a set of plugs with 500 to 900 degrees C marked on the box. Spark plug gap depends on if you are using electronic ignition or not, the engine, etc. Spark Plug Gap – .024-.028. Remedy: Adjust air/fuel mixture. The ability to read your plugs can be a valuable asset when evaluating the health of your racing engine. On shorter, more technical tracks, you will need to gear with a rear sprocket large enough to rev just above 16,000. But without spark to ignite the mixture, nothing will happen. The thread I linked to recommends .040" if you've got a '74-down style head with the spark plug tubes. Poor starting characteristics. When tuning your BMW N55, S55, S63TU it is recommended to go with 1-step colder spark plugs. These substances do not burn as cleanly as the fuel and build up on surfaces in the chamber. Can also be from dirty air filter or using a spark plug that is too cold and cannot self clean. The porcelain is the insulator between the center electrode and the spark plug housing. Re: Anyone Know The Spark Plug Gap Jul 29 2020, 8:01am In 2007 Bulletin No. Coil On Plug – .022-.026. Remedy: Check the engine, ignition, and carburetor. Electricity will also take the path of least resistance, so if too much air is between the spark plug electrodes, the shortest path may be somewhere else—like between the spark plug wires, or the wires and the engine. The gap spacing of general spark plugs is between 0.6 and 1.3 mm. This is called detonation, or "pinging." Cause: Excessive amounts of substances other than the fuel involved in the combustion process. Misfire Diagnosis: Most ignition misfires get worse under load. Also, the spark plug gap should never exceed .055" unless pre-set by the manufacturer. The owner manual says Denso or NGK Iridium plugs. Cause: Plug exchange interval has been exceeded. Gasoline internal combustion engines need three fundamental things: fuel, oxygen, and spark. I nab a four-set of NGK Laser OE spec Iridium Plugs. The trusted spark plug in this platform would be the NGK Iridium IX plugs (part # 6510). Some engines will run fine at idle and light throttle, but will misfire badly under load. Spark plug gap refers to the gap between the spark plug center electrode and the grounding electrode. Spark Plug Gap. The spark plug gap adjustment should not be changed more than 3 times and should not exceed .008" in either direction. Here are a few tips to make sure your engine is getting the spark it needs. The recommended spark plug gap is designed to be adequate for cold starting and smooth driving on a car that is in need of an engine tune up. GEARING/RPM: Gear to achieve a top rpm 15,500 to just above 16,000. However, large spark plug gaps can be more trouble than they're worth. Check plug-to-piston clearance at TDC (top dead center). If replacing plugs doesn't solve the problem, check the spark plug wires, as they may be arcing to each other or electrical ground. Ironically, the car manufacturer's recommended spark plug gap is not optimal! BavAuto ignition coils & NGK spark plugs vs. OEM ignition coils & BOSCH spark plugs. Effects: Can lead to auto-ignition with loss of power and possible engine damage. See all 2 photos. Indexing plugs is a method of ensuring the open end of the ground electrode faces the center of the combustion chamber (the point of the ground electrode is pointed between the intake and exhaust valves). Mechanical ContactElectrode, insulator, and/or ground electrode show signs of mechanical damage. Mist the engine with water in a spray bottle. Also, you run the risk of sending the engine into detonation. Another cause may be that overheating has not taken place. If you are confident you can detect pre-ignition early, keep pushing until you detect the start of detonation and then back off one heat range. When you raise compression or add forced induction (a turbo system, nitrous, or supercharger kit), you must lower the gap (reduce gap about .004" for every 50 hp you add on an V-8 engine, for a Harley-Davidson V-2 engine every 12.5 hp you add). Higher combustion temperatures from boost or increased compression sometimes call for a "colder heat range" spark plug, as the risk of fouling is a reduced under these conditions. Jetting: Jetting = the air/fuel mixture ratio shows up on the base ring (the last thread ring, it has the strap welded to it). This is important because no internal combustion engine is perfectly efficient. Bosch USA has put together an excellent photo library of different plugs that have operated in various engine conditions. So it’s time to change the plugs on my 02 Camry 4-cylinger. Cause: Overheating caused by auto-ignition, for instance the ignition being too far advanced, combustion deposits in the combustion chamber, defective ignition distributor, or poor-quality fuel. Check and Set Spark Plug Gap: The air-fuel mixture is ignited when a spark "jumps" the gap between the spark plug electrodes. More Boost = Less Gap. Spark plugs normally come without the gap set. Understanding this phenomenon is important when diagnosing misfires. Center Electrode Covered with Melted DepositsMelted deposits on center electrode. The center electrode ends in a gold or palladiu… Glazing results from high engine loading after extended part-load operation. When the plug gap is set too wide, the tendency is for the spark to be unable to jump the gap–and thus gets blown out or drown in the fuel mixture. The ability to "read" a set of plugs is an old-school skill, but it is still invaluable at the track. To adjust the gap, thread the spark plug into the gapper tool and measure the existing gap with a feeler gauge. One tuning factor inherent in spark plugs that is largely misunderstood is what's known as a plug's heat range. Check chart below for compatibility on other models. If installing a bolt on supercharger kit or turbo kit and using pump gas, the NGK Iridium BKR8EIX plugs are needed. Cause: Lead additives in fuel. Why? You can use a tiny screwdriver to carefully scrape the side electrodes clean but do not scrape the center electrode as it’s easy to crack or break the ceramic insulator part. The spark plug has several sections to read to determine the engine tune-up: the porcelain, the housing ring around the porcelain, the strap or outer electrode, the center electrode shape, and the threads. By clicking Sign Up, you agree to the  Terms of Use. Believe it or not, that may be true with a '55 Chevy but less so with a modern racing engine. GAP-preset at 0.024" (0.6mm) Iridium alloy has extremely high melting point, perfect for today's high-tech, high-performance engines ... +1 Colder plugs are intended for cars with extreme performance engine mods, Stage 3 Manic Tunes and sustained high RPM track driving running 100+ octane fuel. The structure of the ash is loose or cinder-like. Maintaining proper spark plug gap is especially important with boosted or high-compression engines, as the additional pressure inside the combustion chamber squeezes more air molecules between the spark plug electrodes—effectively increasing the spark plug "gap.". original part BKR6E-11 (1.1mm gap) can be replaced by BKR6E which has a preset gap of approx 0.8mm) - this is preferable to adjusting a larger gap which can put the electrodes out of true and also weaken the ground electrode. The buildup is usually from oil in the combustion chamber or fuel additives. Worn oil rings will allow oil into the combustion chamber. One tuning factor inherent in spark plugs that is largely misunderstood is what's known as a plug's heat range. Cause: Incorrect mixture setting on carburetor, causing rich condition. A plug that is too hot will pre-ignite the air/fuel charge before the plug actually fires. NGK SPARK PLUG SAAB 4 CYLINDER quantity. We've found the NGK SILZKBR8D8S (97506) in the picture attached working great when gapped to appropriate spec. The spark plugs are manufactured for VW/Audi by NGK. The Latest "M-Revision" RS7 plug is one heat range colder than the original plug in the 1.8T / 2.0T engines, and both center and ground electrodes have an Iridium coating. Insulator tip blistered, spongy, or soft. 100HP Over Stock = 1 Step Colder Plugs. When that carbon sticks to the surface of the valves or the piston top, it is no big deal, but a spark plug is much more fragile, and buildup can cause fouling. The spark plug also has a steel jacket, which allows the threaded end of the plug to be torqued into the cylinder head. The o. manual says a .043 gap so I check them with my feeler guage and note they are off - just a tad; I adjust the gap a bit farther being careful not to abrade the electrode surfaces. Remedy: Cleaning glaze off plugs is pointless. For more info, check out the Bosch Web site. It’ll bend a little bit with each tap so go gently. SPARK PLUG: NGK BPR9EIX (IF PERMITTED) NGK R6252K-105 (FOR USE AT SKUSA, WKA, USPKS) SPARK PLUG GAP: 0.03 IN OR .762 MM. Check the gap with a spark plug gap tool (cheap or free at most parts counters) and set this gap to.024 –.028. Pre-ignition leads to detonation (otherwise known as knocking), an extreme buildup of pressure in the combustion chamber that can cause severe engine damage. Excessive Wear on Ground ElectrodeGround electrode is worn down, resulting in excessive plug gap. HEI ignitions should be able to run a bit more gap - .045" or so, sometimes more if you have a really hot spark. Most tuners advise.025-inch to.030-inch gap under these conditions. Check air filter. By clicking Sign Up, you agree to the  Terms of Use. Effects: Misfiring, difficult cold starting. Your information will be collected and used in accordance with our  Privacy Policy. Indexing plugs in this situation may help produce an increase of several horsepower, but in a modern racing engine, it should not make much difference at all. Step 3: Fuel The culprit may be spark plugs that are badly worn or gapped improperly. Photos and information are courtesy of Bosch USA. Measure the gap, adjust it and repeat until you get accurate results. Effects: The spark plug does not fire. In this case, I wanted to set the gap to 0.020″, so I tightened the knob until the 0.020″ blade fit perfectly in between the gap. Gap preset at 0.9mm :- ($ 2.00) Gap not set – must be done at installation. The larger the spark plug gap is, the longer the arc will be generated when igniting. If the plug gets too hot, however, you have bigger problems. This increased voltage is hard on the rest of the ignition system (wires, coil, amplifier, and distributor cap and rotor). Remedy: Switch to spark plugs with less depth. Locate the spark plug (s) on the top of the engine and remove the cable, exposing the top of the plug. Fit new plugs. All Magnum tuning parts are tested individually before they ship out. For some plugs, equivalents with a smaller preset gap are available (e.g. All my gaps measured .044. Spark Plugs Double check what your tuner will want you to use, but in general, people will use one step colder plugs gapped down to a.026. One plug will run perfectly in one type of engine but be too hot or too cold in a different engine. Evo 7/8: Stock heat range: Fit new spark plugs. If you race a limited stock class that requires OEM cylinder heads and allows nothing more than cutting new seats, you might consider indexing the plugs. With the exception of power loss from a dead cylinder, this causes no damage to the engine. When you are tuning an engine, it's best to always start off with a cold set of plugs because the only damage you are going to do is to the plug, not your engine. If you race a class that allows modern aftermarket cylinder heads, indexing should not show much value. Because there are so many variables involved in racing engines that affect a spark plug's operating temperature, it's difficult to determine which plug will best fit a specific application without testing. Remedy: Check the engine, ignition, and carburetor. This assures that the flame front moves across the widest section of the combustion chamber before it reaches an obstruction in the form of the chamber wall. The ports and combustion chamber are designed better and are more efficient at burning the air/fuel charge. Excessive changing of the spark plug gap setting will result in weakening of the spark plug ground electrode and can lead to breakage. : 03-06-04-060A was put out that basically said for 99-04 Silverados and Sierras the spark plugs were changed to iridium from platinum and thus the gap was changed to .040 You can then adjust the mixture by tuning the mixture adjusting screw … Plug gap should be between 0.018~0.028" depending on the condition of the ignition coils. "Hotter heat range" plugs are less likely to "foul" because they stay hotter between combustion cycles and burn off any harmful deposits left behind. Effects: Misfiring, loss of power, and potential engine damage. Wes Duenkel Writer, Photographer. Changing the electrode gap is called a spark plug gapping. This precision tool is critical to properly and accurately gapping spark plugs. Spark Plug Gap Option *. It may also be a result of aggressive fuel and/or oil additives, unfavorable flow conditions in combustion chamber (possibly as a result of combustion deposits), or engine knock. The Colortune spark plug is screwed into the engine in place of the normal plug.