i need to know if a hotter plug or colder plug will help with performance on a stock machine and the parts stor only has ac delcos so how would i read the numbers to dtermine wich is hotter or colder

 

Frequently Asked Questions http://www.ngksparkplugs.com/techinf...200&country=US

Q: How often should I replace my spark plugs?
A: Unfortunately, there is no single answer to this question. As spark plugs grow older, they lose their sharp edges as material from the center and ground electrodes is slowly eroded away. As the gap between these two points grows, the voltage required to bridge the gap increases proportionately. Even the best ignition systems will be strained to supply enough voltage to completely burn the fuel. It is at this point, when fuel is being left unburned, that the time has come to change spark plugs.
Replacing worn out spark plugs with new ones (with sharp new edges) effectively restores the ignition system's efficiency. Misfires are reduced, power is restored, economy of operation is enhanced and emissions are reduced.
The best guide is the manufacturer's recommendation for your vehicle, as this particular service varies from brand to brand and model to model. In the absence of this information or in conjunction with it, you can rely on the advice of a mechanic who is familiar with your type of vehicle. In the best of all worlds, this would be a mechanic who is also familiar with the vehicle you own. If you find a good mechanic, whether dealer or independent, stick with him. The better he knows your personal vehicle, the better he will be able to diagnose and service it. The end result is very much like a doctor-patient relationship and, in the long run, you will have a healthier vehicle.
Q: How do I choose the right spark plug?
A: There are several factors - such as thread reach, thread diameter, the insulator nose projection and whether the spark plug incorporates a gasket or is of the conical type - to consider when choosing the correct spark plug for your needs. If you have a stock factory vehicle, just click here to use the Part Finder and follow the prompts to find the appropriate plug for your needs. You can also ask specific questions here.
In most cases, it is not until the engine is modified, or the compression is raised significantly, that stock ignition systems and spark plugs begin to show signs of being inadequate. At this point, a variety of factors determine which spark plug will be best suited for a particular configuration. In these modified engines, specific electrode/tip combinations, electrode materials and colder heat ranges can provide measurable gains in power. If your vehicle has had extensive modifications, it would be best to seek the advice of the manufacturer of your vehicle, the aftermarket supplier who manufactured your modifications, or your mechanic.
Q: How do I "read" a spark plug?
A: Being able to "read" a spark plug can be a valuable tuning aid. By examining the insulator firing nose color, an experienced engine tuner can determine a great deal about the engine's overall operating condition.
In general, a light tan/gray color tells you that the spark plug is operating at optimum temperature and that the engine is in good condition. Dark coloring, such as heavy black wet or dry deposits can indicate an overly-rich condition, too cold a heat range spark plug, a possible vacuum leak, low compression, overly retarded timing or too large a plug gap.
If the deposits are wet, it can be an indication of a breached head gasket, poor oil control from ring or valve train problems or an extremely rich condition - depending on the nature of the liquid present at the firing tip.
Signs of fouling or excessive heat must be traced quickly to prevent further deterioration of performance and possible engine damage.
Examples of common problems that effect the firing nose of the plug >>
Q: What is a "fouled" spark plug?
A: A spark plug is considered fouled when the insulator nose at the firing tip becomes coated with a foreign substance such as fuel, oil or carbon. This coating makes it easier for the voltage to follow along the insulator nose, leach back down into the metal shell and ground out rather than bridging the gap and firing normally.
Many factors can contribute to spark plug fouling. The air/fuel ratio may be too rich as a result of incorrect carburetor adjustment or a poorly performing fuel injection system. Worn piston rings or valve seals may allow too much oil to leak into the combustion chamber, leading to oil fouling. The ignition system may not be performing properly. Prolonged idling or continuous low-speed driving may keep the spark plug from reaching its optimum operating temperature. Using too cold a spark plug can lead to the same problem. Finally, a dirty air cleaner can create a too-rich condition which can lead to fouling.
Fuel, oil and carbon fouling can all be the result of different causes but, once a spark plug is fouled, it will not provide adequate voltage to the firing tip and that cylinder will not fire properly. In many cases, the spark plug cannot be cleaned sufficiently to restore normal operation. Therefore, it is recommended that a plug be replaced once it is fouled.

Q: Can old spark plugs be cleaned
A: Yes, you can clean spark plugs. However, it is good to remember that spark plugs are a wearable item, so it's important to make sure you check to see if it's worth cleaning before you go through the following steps.
If the firing end is wet, make sure you clean the spark plug with
a quick drying cleaner. (Examples: contact cleaner or brake cleaner).
Sand blast the spark plug using low air pressure
and use a dry compound.
Completely blow all the sand from the spark plug.
Using a wire brush clean the threads and re-gap.
NOTE: Insufficient cleaning of the spark plug may lead to spark plug failure in a very short period of time. Clean the spark plug thoroughly to avoid problems later. Remember, if a spark plug is fouling it's usually a result of engine side factors or incorrect heat range selection.
Q: How much of a performance improvement can I expect from changing plugs?
A: A common misconception is that changing spark plugs will result in a large power increase. In most cases, removing even seriously worn out spark plugs will only result in very modest power gains, typically about 1-2% of total engine output. This could be even less for computer-controlled vehicles, primarily because most newer vehicles have more powerful ignition systems and the vehicle's computer can make adjustments so that vehicle operation seems smoother and more seamless.
Many people think that simply supplying more spark to the firing tip can and will combust more fuel. What they don't understand is that most newer cars' engines are so efficient that they are already burning all of the available fuel. Simply adding more spark voltage can't burn more fuel because there is no more fuel to burn.
When a stock or near-stock engine is given a fresh set of spark plugs, peak efficiency is restored. The power gains that come from this restored state of tune are usually minimal. Any company that tells you that their spark plug will provide significant gains in power in a stock or near-stock engine is making blanket statements that may not be supportable.
Q: Are special plugs always necessary on a modified engine?
A: It depends on the modifications. The term "modified" refers to those engines that have received bolt-on improvements that may or may not raise the engine's total compression ratio. These can include turbocharging, supercharging, nitrous oxide injection, the use of smaller-chambered cylinder heads, modified piston configurations, free-flowing cylinder heads, change of induction components and/or the use of different fuel types and octane. These kinds of modifications generally require a change from stock spark plugs.
Modifications that will typically not require specialized plugs (in most cases the factory installed plug will be more than adequate) include adding a free-flowing air filter, headers, mufflers and rear-end gears. Basically, any modification that does not alter the overall compression ratio will not usually necessitate changing plug types or heat ranges. Such minor modifications will not significantly increase the amount of heat in the combustion chamber, hence, a plug change is probably not warranted.
However, when compression is raised, along with the added power comes added heat. Since spark plugs must remove heat and a modified engine makes more heat, the spark plug must remove more heat. A colder heat range spark plug must be selected and plug gaps should be adjusted smaller to ensure proper ignitability in this denser air/fuel mixture.
Typically, for every 75-100 hp you add, you should go one step colder on the spark plug's heat range. A hotter heat range is not usually recommended except when severe oil or fuel fouling is occurring.
Submit any questions you may have regarding special modifications or fuel usage here.
Q: Why are there different heat ranges?
A: It is a common misconception that spark plugs create heat. They don't. A heat range refers to how much heat a spark plug is capable of removing from the combustion chamber.
Selecting a spark plug with the proper heat range will insure that the tip will maintain a temperature high enough to prevent fouling yet be cool enough to prevent pre-ignition. While there are many things that can cause pre-ignition, selecting a spark plug in the proper heat range will ensure that the spark plug itself is not a hot spot source. More information about heat ranges can be found here. heat range http://www.ngksparkplugs.com/techinf...tnumberkey.pdf
Q: Does compression ratio affect firing end temperature?
A: Yes, the by-product of increased compression is the elevation in cylinder temperatures. This is why it is recommended to choose a spark plug suitable for your application. NGK Spark Plugs recommends dropping heat ranges and altering Air/Fuel mixtures and timing as needed. It is very important to dissipate the excess heat from the combustion chamber in order to prevent pre-ignition.
Q: What is pre-ignition?
A: Pre-ignition is defined as the ignition of the air/fuel mixture before desired ignition timing.
Q: What is detonation?
A: Detonation is a spark plugs worst enemy. It can break insulators and ground electrodes. Spark plug temperatures can reach in excess of 3000 °F.
Detonation, in simple terms, is a violent uncontrolled burn of the air/fuel mixture, which occurs when excessive heat and cylinder pressure causes the air/fuel mixture to spontaneously ignite.
Q: What do the numbers and letters in a part number represent?
A: The various numbers and letters in a spark plug code or identification number basically identify the features and functions of a particular plug. Included would be information such as plug type, heat rating, construction, thread diameter, thread reach and firing end construction.
Click on the link below to download a guide that will help you decipher the various NGK alpha-numeric combinations. You will need to open it with Adobe Acrobat Reader. If you do not already have Acrobat Reader installed on your computer, we've provided a link to the free download area for your convenience.