Article > Tech

Charging Up Ignition Part Sales

By Gary Goms

Consider all the SKUs your store has to carry just in spark plugs, and you can see how ignition system parts are fast becoming a complicated line to manage.

Selling ignition parts often becomes a confusing process, especially for a counterpro who must recommend a specific quality or quantity of ignition parts for specific applications. Too often, the ignition parts catalog doesnt cover the level of performance for which the part may be engineered or for which applications it may be specifically designed.

For example, most jobbers offer a second-line brand that is more price-competitive than their first-line store brand. Lets begin by asking ourselves to which level of performance the second-line brands may have been engineered.


Distributor caps and rotors offer a good point of comparison between second-line versus first-line brands because the qualitative differences can be easily seen when the parts are placed side-by-side. The first-line distributor cap is usually made out of a high-density material that has a very high level of dielectric strength to prevent a 40,000- to 60,000-volt ignition spark from arcing to a convenient ground on the distributor housing. Often, this density causes the first-line brand to actually feel heavier. If you look closely, the first-line distributor rotor may also feel heavier and have a beefier design than the second-line rotor.

Next, the first-line cap and rotor will usually be made with brass contacts, which are designed to last much longer than the second-line cap and rotor, which may have the cheaper, low-quality aluminum contacts. As for actual installation, the first-line brand usually has better fit and either meets or exceeds the original auto manufacturers performance specifications. The second-line cap and rotor may perform as well, but not last as long. In some cases, the second-line brand may fail prematurely under severe-use conditions.

The characteristics of first- and second-line spark plug wires play a big role in how you sell these particular products. First-line spark plug wires are designed to be direct replacements for the original equipment wires. In other words, the length of each wire, the mechanical strength of the connections and spark plug boots, the electrical resistance, the insulating properties, the resistance to oil, solvents and weathering, and the quality of the mechanical connectors duplicate original equipment wires.


As for installation, high-quality wires are easy to install because theyre supplied in OEM lengths and, since the mechanical strength of the connectors is OEM equivalent, the wires snap on and off the spark plug in a very positive manner. Better still, the wires can be removed 30,000 miles later without the boots or connector ends pulling off the wire itself. In contrast, second-line wires usually sacrifice or compromise at least several of the above properties in order to achieve a pricing point in the retail market.

So, how do you sell spark plug wires? First, ask your customer if the wires are difficult to install. Many minivan configurations, for example, may require up to three hours to change a set of spark plug wires. In these instances, the price of the first-line wires will pay for itself in "user-friendliness" to the installer. Second, if the vehicle has a remaining life expectancy of 50,000 miles or more, the first-line wire will render more value through its mechanical durability and relatively low electrical failure rate than will the second-line wires.

On the other hand, there is a very applicable market for second-line wires on older vehicles nearing the end of their normal service lives. They also work well in vehicles on which the wires are easily replaced, such as a 1980s model four-cylinder, front-wheel-drive compact.

Of course, using the second-line wires does include at least one caveat, which is their use on post-1996 OBD II vehicles. OBD II engine computers include a misfire monitor that turns on the Check Engine light if a cylinder misfire occurs that may endanger the catalytic converter.

Several auto manufacturers recommend changing spark plug wires at specific service intervals in order to prevent a catalyst-threatening misfire from occurring. While preventive-maintenance wire changing on these vehicles is most often recommended each 60,000 miles, the vehicle owners manual may specify slightly longer intervals. In any case, OEM-equivalent wires should be recommended to meet the OEMs service requirements on 1996 and later OBD II-equipped vehicles.

Since the variations on the modern spark plug are seemingly endless, its no wonder that the average counterpro has a hard time recommending spark plugs. So lets get back to basics.


First of all, the job of the spark plug is to ignite the air/fuel mixture in the combustion chamber by allowing a high-voltage spark to arc across an air gap that is about the thickness of a dime.

To do this efficiently over a long period of time, the spark plug firing tip temperature must exceed 700 degrees F to burn off fuel and oil deposits. When deposits accumulate on the firing tip, the high-voltage spark is shorted to ground, which causes the air/fuel mixture not to ignite. On the other hand, if the firing tip exceeds 1,500 degrees F tip temperature, it will pre-ignite the air/fuel mixture too early in the combustion cycle and may burn a hole through one or more of the engines pistons.

Throughout the 1970s, a recommended spark plug change interval of 12,000 miles was established primarily due to wear, oil ash and ethyl lead deposit accumulation occurring on the spark plug electrodes. Beginning in the late 1980s, the change interval was extended to 30,000 miles because the introduction of unleaded gasoline, electronic fuel injection and high-voltage, computerized ignition systems reduced deposit formations. In addition, copper-core spark plugs were introduced which had a much broader heat range than conventional core spark plugs. Because copper core spark plugs ran cooler with fewer deposits, they became standard equipment on most 1980s and later engines.

Of course, as engine compartments became jammed with accessories, spark plug access became much more difficult in many vehicle configurations which made replacement times typically jump from 30 minutes to as long as three hours. In addition, improved oil control in modern engines allowed auto manufacturers to extend the spark plug replacement interval to 100,000 miles.

In order to make the spark plug electrodes themselves last 100,000 miles, spark plug engineers began coating the electrodes with precious metals like platinum, gold or iridium. Engineers also recognized the affinity conventional steel spark plug shells had for bonding with modern aluminum cylinder heads, so they designed smoother spark plug threads and coated them with nickel or similar metals that resist bonding with aluminum.

What should a counter professionals recommendations be for spark plugs? Keeping in mind that were following a catalogs recommendations for specific applications, the conventional steel spark plug should work just fine in 1980s and earlier cast-iron engines. Copper core spark plugs should work equally as well for 30,000-mile change intervals, while the platinum or precious metal plugs are the minimum requirement for the 100,000-mile replacement interval.

As for controversial issues, will platinum spark plugs improve engine performance and fuel economy? Maybe, on a well-tuned engine that doesnt burn oil. Can copper-core plugs be substituted for platinum plugs? Its not recommended, because the copper core plugs wont last nearly as long as platinum plugs. Furthermore, the proper shell coatings may not be present in copper-core plugs, which will allow the spark plug threads to seize to an aluminum cylinder head.

Very often, counterpros must supply advice on high-voltage aftermarket ignition systems and specialty spark plugs.

If, for example, an enthusiast is building a high-compression, high-rpm racing engine, he will likely need a high-voltage, multiple spark ignition system. On the other hand, if hes trying to squeeze more performance out of a stock-block engine application, hes likely wasting his money since the capacity of most 1980-and up stock ignitions far exceed the demands of a stock engine.

As for spark plug recommendations, a specialty-gap spark plug may actually improve performance and fuel economy a slight amount in a stock engine. Any improvement, however, depends upon the deficiencies inherent in any particular application. Some engines might benefit more than others, so the customer buys and installs them at his own risk. Just another issue, you might say, in selling modern ignition system parts.

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