Spark plug wires have two main objectives; transfer the spark energy to the plugs and suppress the Electro Magnetic Interference (EMI) that the spark voltage projects. Too high of resistance decreases the spark energy, yet too low of resistance may generate too much EMI noise which will interfere with the operation of other electronics on the vehicle. A good quality wire, proper routing and routine inspection are all important in getting the most performance out of your ignition system.
MSD offers two great spark plug wires; Heli-Core Wire and the 8.5mm Super Conductor Wire. The Heli- Core Wires are a premium performance wire upgrade for any car or truck. For serious performance, the 8.5mm Super Conductor Wire is the wire of choice. Both sets of wires feature a conductor that is helically wound around a special center core that is designed to suppress, or choke, EMI. Helically wound, sometimes called spiral core, must be used with an MSD Ignition Control. Solid core wires do not suppress EMI so there could be interference with the ignition or other electronics on the vehicle.
The Super Conductor Wire has less than 50 ohms per foot, the lowest available in a helically wound wire. A special copper-alloy conductor is wrapped very tightly around a ferro-magnetic impregnated center core which gives the wire extremely high EMI suppression. This design ensures that optimum spark energy will reach the spark plugs while EMI noise is held at a minimum.
Note: Solid Core spark plug wires cannot be used with any MSD Ignition controls or Pro Mags.
Just like tires, oil or spark plugs, the spark plug wires are a maintenance item. Service of the wires hinges on your application and ignition control. If you have a 6AL Ignition and use the car as a daily driver, the wires will last for thousands of miles. Conversely, if you are racing a high compression engine with nitrous and an MSD 10, the wires should be inspected and even replaced during the race season. When checking wires, closely inspect for signs of burning or arc-through. Look at the boots for signs of cracking or burning and using an ohm meter to check resistance of each wire is a good idea. Also, keep in mind that the coil wire is delivering eight times the spark so it should be checked closely. When checking resistance of the wires note that the longer wires will have more total resistance, but their values should average out. If one wire stands out among the others, it should be replaced.
To keep your engine’s spark plug wires in tip-top condition there are a few simple steps you can take. For starters, apply a small amount of MSD Spark Guard, PN 8804, a dielectric grease, to each wire terminal. This keeps any moisture out of the boot while lubricating and insulating the terminal- to-plug connection. It also aids in pulling the plug socket off without tearing the boot or wire.
Extra protection from heat is always a good idea. MSD wires have a very durable sleeve but in applications with tight engine compartments and close exhaust systems, additional protection is a benefit. MSD offers Pro-Heat Sleeve, PN 3411, a silicone coated woven glass sleeve that slides over your wires for added protection. If you're looking for protection around the boot MSD's Pro-Boot Guard, PN 3412, is the answer. This is an extra thick sleeve of woven glass with a silicone coating and will protect the boot from excessive heat.
Another important point to consider is the way the plug wires are routed. Using good wire separators is a key in preventing inductive crossfire which occurs when two wires that are consecutive in the firing order are run next to each other. MSD offers a variety of Separators that will help position the wires away from exhaust manifolds and sharp edges while keeping the engine compartment looking good.
Note: Distributor caps that re-route the wires to the left and right are not recommended with an MSD Ignition Control.