Best spark plug gap for MPG
#1
07-21-2011, 08:00 AM
Best spark plug gap for MPG
I found this article a few years ago and would like to discuss the best spark plug gap for fuel efficiency.
"Get NGK V-power plugs and set the spark plug gap to 0.030 for best results. Or close your wide factory gap by .020-.030. Use dielectric grease on your plugs and in the plug wire boots and on the metal contacts. Silicone spray is okay but the grease is better because the next time you remove the boots, it is possible to rip the cables and damage the wires to introduce a missing condition in the ignition. It is also a good idea to put anti-seize on the plug threads. Champion and AC plugs have tremendous resistance levels that simply waste spark energy. Measure the resistance for yourself. Please use compressed air to blow out dirt from around the plugs BEFORE you remove them. Otherwise dirt falls into the cylinders and causes rapid ring wear. I use fish hook extractor pliers to grab my plugs in and out of a deep hole. Be sure your plug cables are like new by viewing the ignition system on a scope if possible. Replace cables if older than five years with NGK or Federal wires. With a tighter gap, voltage is less but amperage is much greater. Amps mean HEAT and that is what fires the air-fuel mixture, not voltage. The more heat, the better the ignition and mileage. Ordinary wires should be replaced every 50,000 miles. It is best to use NGK V-power or get Bosch Super spark plugs as they have the proper (lower) resistance levels. Some AutoLite plugs have a lower resistance and are okay. But ALWAYS check the plug resistance to be sure it does not exceed 7000 ohms. Please ignore most mechanics opinions about plugs. For instance we avoid platinum and iridium plugs because people tell us their cars do not run as well. We pay close attention to what people tell us about their actual results. Remember mileage and power go together."
From wikipedia:
"The gap adjustment can be fairly critical, and if it is maladjusted the engine may run badly, or not at all. A narrow gap may give too small and weak a spark to effectively ignite the fuel-air mixture, while a gap that is too wide might prevent a spark from firing at all. Either way, a spark which only intermittently fails to ignite the fuel-air mixture may not be noticeable directly, but will show up as a reduction in the engine's power and fuel efficiency.
With a narrow gap, the spark might be too weak/small to ignite fuel, but the plug will almost always fire on each cycle; a plug with a wide gap might not fire, or missfire at high speeds, but will usually have a spark is strong for a clean burn. A properly gapped plug will be wide enough to burn hot, but not so wide that it skips or misses at high speeds, causing that cylinder to drag, or the engine to begin to rattle."
"Get NGK V-power plugs and set the spark plug gap to 0.030 for best results. Or close your wide factory gap by .020-.030. Use dielectric grease on your plugs and in the plug wire boots and on the metal contacts. Silicone spray is okay but the grease is better because the next time you remove the boots, it is possible to rip the cables and damage the wires to introduce a missing condition in the ignition. It is also a good idea to put anti-seize on the plug threads. Champion and AC plugs have tremendous resistance levels that simply waste spark energy. Measure the resistance for yourself. Please use compressed air to blow out dirt from around the plugs BEFORE you remove them. Otherwise dirt falls into the cylinders and causes rapid ring wear. I use fish hook extractor pliers to grab my plugs in and out of a deep hole. Be sure your plug cables are like new by viewing the ignition system on a scope if possible. Replace cables if older than five years with NGK or Federal wires. With a tighter gap, voltage is less but amperage is much greater. Amps mean HEAT and that is what fires the air-fuel mixture, not voltage. The more heat, the better the ignition and mileage. Ordinary wires should be replaced every 50,000 miles. It is best to use NGK V-power or get Bosch Super spark plugs as they have the proper (lower) resistance levels. Some AutoLite plugs have a lower resistance and are okay. But ALWAYS check the plug resistance to be sure it does not exceed 7000 ohms. Please ignore most mechanics opinions about plugs. For instance we avoid platinum and iridium plugs because people tell us their cars do not run as well. We pay close attention to what people tell us about their actual results. Remember mileage and power go together."
From wikipedia:
"The gap adjustment can be fairly critical, and if it is maladjusted the engine may run badly, or not at all. A narrow gap may give too small and weak a spark to effectively ignite the fuel-air mixture, while a gap that is too wide might prevent a spark from firing at all. Either way, a spark which only intermittently fails to ignite the fuel-air mixture may not be noticeable directly, but will show up as a reduction in the engine's power and fuel efficiency.
With a narrow gap, the spark might be too weak/small to ignite fuel, but the plug will almost always fire on each cycle; a plug with a wide gap might not fire, or missfire at high speeds, but will usually have a spark is strong for a clean burn. A properly gapped plug will be wide enough to burn hot, but not so wide that it skips or misses at high speeds, causing that cylinder to drag, or the engine to begin to rattle."
#2
07-21-2011, 12:20 PM
I have found that the engineers who built the car usually are dead on in the tune up specs. I have always used NGK in my Hondas, Toyotas and Honda motorcycles as a rule. If the spec calls for 0.030, that is what I gap the plugs at. MPG is more relative to traffic/driving habits than other factors in this instance. A heavy foot will affect mileage more than anything in the tuning of the engine.
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