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Ignition Wiring - Secondary ThoughtsKnow Your Wire Before You Fire From the April, 2010 issue of Rod & Custom By Rob Fortier
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Have you ever put much thought into the specifics of your car's ignition system-above and beyond the simple fact of whether it's working or not, that is? More specifically, how about those spark plug wires you're running? Aside from passing a quick visual inspection to detect any loose connections, burnt insulation, and whatnot, are you even using the correct type of wire to begin with? Yeah, they may refer to this as the "secondary" side of the ignition, but oftentimes, some rarely give their plug wires a second thought ... unless it's which color goes best with the engine compartment. What was once old ...Vintage... What was once old ...Vintage Reproduction Parts now offers their modern version of the cloth-covered plug wire. Though not of the spiral-wound construction, the stainless core wire does have better insulating capabilities than the original type it's based on. The lacquered cloth housing is available in yellow (with red/black accent) or black, in both straight and 90-degree versions. Lately, we've been seeing quite a few "new" builds using "old"-style spark plug wires. To the naked eye, the lacquered, cloth-wrapped wires look identical to the original ones-and in many cases, they are just that ... NOS solid-core, non-suppression wires. They could, however, be a modern spiral-core dual-insulated wire hiding behind a braided cloth outer shell. Each has its place, so before you go off and ruin a brand-new electronic ignition system, make sure you're well aware of what goes where and what does what. First off, your particular ignition system will tell you what type of plug wire you should or-more importantly-shouldn't use. Early points-style ignitions and magnetos used low-resistance wires to carry a lower voltage as compared to modern systems, which can easily carry up to twice the load, thus requiring a higher tolerance wire. Running a modern, spiral-core suppression wire with the early ignition can actually decrease the voltage being carried to the plugs; running the early solid-cores with a high-output (breakerless, capacitive discharge, or HEI) system can easily result in damaged electronic components for the exact opposite reason. There's more to a plug wire than the color of its skin. The only way to accurately tell one type of wire from another is to go beneath its skin to reveal its core construction. Basically, there are three main types of ignition wire: solid-core, carbon-suppression, and spiral-wound. As previously mentioned, each has its place when it comes to specific types of ignition systems-rarely can they perform up to par when used outside their initial realm (mostly applies to the solid conductor wires, which can't be suppressed). A solid wire offers virtually no resistance, as it was designed to deliver the maximum amount of spark from a low-output ignition. This type of plug wire is perfectly suited for a points-style distributor (but NOT one that's been converted to electronic!) or with a magneto; used with an electronic ignition, a solid wire cannot protect the sensitive components like a properly insulated wire can. A carbon-conductor wire, on the other hand, does offer the shielding characteristics needed for a "basic" electronic ignition (with the terminals acting as resistors), however, its high level of suppression (designed to prevent noise/radio interference) equates to reduced spark travel. A spiral-wound or induction-type wire offers the same or more high suppression as a carbon-core, but unlike its predecessor, has the low resistance necessary for optimum spark, making it perfectly suited for performance ignition systems. Knowing the differences between the types of wires and ignition systems is important, but when it comes to the higher-end of the performance scale, always refer to the manufacturer's requirements, specifically the ohm resistance. For higher performance applications... For higher performance applications (i.e. aftermarket electronic ignition systems), solid- and carbon-core wires won't carry the load-literally. In order to transmit maximum spark while still suppressing radio noise/interference, a spiral-wound or induction-type wire such as MSD's Super Conductor 8.5 mm is required. When purchasing an aftermarket performance wire, such as an MSD 8.5mm Super Conductor, Mallory 8mm Pro Sidewinder, or the "little" underdogs, ACCELL 5mm Ferro-Spiral, the final decision may ultimately rely on personal preference, as they're all quality high-performance wires. But not every ignition requires such a high level of performance, in which case something along the lines of the 7mm Stock-Look wires from PerTronix are not only well above average performance-wise, but can be ordered pre-fit for many applications. Fortunately, for those wanting the real old-timey look, there are more options now to choose from-just ensure that you know what you're buying before you buy, as there are many variations of vintage-style plug wires available to consumers these days. While some, like me, prefer a universal kit over pre-fit, when it comes to the actual "fitting", the end result-crimping of the terminal-can literally make or break (emphasis on the latter) a wire when it comes to achieving optimum performance. Like many things, it just takes a little patience, following procedure, and of course the right tool. Starting with a cut-to-fit wire set will allow you to custom-tailor the wires to your specific engine configuration, which is especially beneficial when working around tight confines, namely block-hugger headers. The key, ultimately, is to route all wires safely around any potential hot spots, which oftentimes means having to run plug wires down toward the oil pan, rather up and along the valve cover, to avoid contact with the headers when dealing with common V-8s. Your exhaust will also dictate what plug terminal boots to use-90-degree or straight. More often than not, tight headers will not allow the use of straight boots. With earlier engines, such as Flatheads and most inliners, exhaust interference isn't a concern. If you've rarely given your spark plug wires a second thought, maybe now's a good time to go pop the hood. While you're in there, check all the fluids too!  Not everyone wants to run...  Not everyone wants to run a big 8 or 8.5mm plug wire, for both performance and aesthetic reasons. In this case, something along the lines of the 7mm Stock-Look wire from PerTronix will cater to their needs by providing the necessary low resistance and high suppression in a factory-looking disguise.  Among the vintage-looking...  Among the vintage-looking ignition wires currently being used these days, there's a bit of discrepancy among the core construction of each. From top to bottom: NOS cloth-wrapped (copper) solid-core, '60s-era carbon-core, cloth-covered spiral-wound, reproduction cloth-wrapped (insulated stainless) solid-core, and reproduction silicone-housed solid-core.  Shown are the two examples...  Shown are the two examples of lacquered/cloth-wrapped wire: on the left, Vintage Reproduction Parts' new 7mm wire with silicone suppression layer insulating a stainless strand core; to the right is the solid-core NOS wire it's modeled after. Along with the added suppression benefits, the reproduction wire features a much heavier exterior coating.  There are spiral-wound versions...  There are spiral-wound versions of the cloth-covered wire available out there for those running an aftermarket electronic ignition such as an MSD 6AL or PerTronix Igniter series. Make sure you have the appropriate core type before installing any vintage-looking wire, as a solid-core will ultimately damage ignition components.  With the reproduction Standard...  With the reproduction Standard Motor Products 7mm wires (available through Speedway Motors and Mooneyes), it's "clear" to see what you get. There should be no confusion regarding what type of wire this is.  Along with the vintage look...  Along with the vintage look of the ignition wire itself, there's also the terminal end to consider. It's important to provide enough added resistance (varies on vehicle particulars) via the terminal, which is one of the reasons Vintage Reproduction Parts uses quality rubber boots.  The Raja terminal is still...  The Raja terminal is still quite popular, but as you can see, leaves little in the way of concealing the spark once it reaches the plug, thus the higher potential of cross firing.  More concealed versions of...  More concealed versions of the Bakelite or plastic terminals are available (mostly in straight configuration) and, for the most part, relatively inexpensive. That said, the cheaper ones tend not to hold up very well over time, as evidenced by the connectors losing their "grip".  With the exception of being...  With the exception of being used on stock points-style ignitions (or with a magneto), I've found these types of terminals to work best as-is ... on the shelf along with other hot rod curios and keepsakes!  For any ignition system above...  For any ignition system above and beyond the OE norm, a spiral-wound inductor-type wire is required, at least if you want to actually get all the performance benefits out of your ignition. No other type of wire can transmit optimum spark with such high suppression characteristics.  There's a broad spectrum of...  There's a broad spectrum of induction-wound wires available today: from high-end 8.5mm MSD Super Conductors all the way down to ACCEL's 5mm Ferro-Spiral wires.  It's helpful to know the difference...  It's helpful to know the difference in terminal ends, at least if you're planning to install a universal set of plug wires...  ... Typically, a manufacturer...  ... Typically, a manufacturer will supply their wires with the plug ends already installed, so the end user is left with the distributor side, either HEI or standard.  When it comes to HEI terminals,...  When it comes to HEI terminals, there are different crimp types, as shown here. MSD uses the dual-crimp style, while many other manufacturers still use the single-crimp...  ...With the dual type, the...  ...With the dual type, the wire core doesn't need to be folded back when crimped.  When it comes to ignition...  When it comes to ignition specialty tools, you can tackle most any job by using manufacturer-supplied crimp dies (usually vise-clamp type). For more frequent use, however, consider a ratcheting multi tool.  Same can be said for wire...  Same can be said for wire stripping when it comes to tool of choice. When using pliers to strip a spiral-core, as shown here, make sure to strip only the insulating layers; damage to the conductor wire will adversely effect performance.  While the ratcheting pliers...  While the ratcheting pliers are nice to have, I often end up using a good old pencil-sharpener type wire stripper that came with a set of Mallory wires years ago.  MSD's supplied crimping die...  MSD's supplied crimping die also features a stripping guide-just insert the wire and, using a razor or X-ACTO knife, carefully trim excess insulation off as you rotate wire inside the guide.  Before crimping a terminal...  Before crimping a terminal onto a plug wire, determine whether or not to install the plug boot  -with standard-type terminals,...  -with standard-type terminals, especially 90-degree ones, it's best to have the boot in place first instead of trying to force it over the terminal and risking the chance of damaging the crimp.  As previously mentioned, the...  As previously mentioned, the HEI terminals used by MSD require two crimps-one for the primary conductor wire as well as the traditional insulation crimp.  The mini-crimp tool does not...  The mini-crimp tool does not have a provision for the conductor wire crimp (simply use a set of pliers), but the multi-tool can perform both crimps almost effortlessly.  If you need to further justify...  If you need to further justify having a ratcheting tool as such, there are replacement crimping dies available, allowing you to perform a number of crimping tasks above and beyond plug wires.  Whether installing a plug...  Whether installing a plug boot before or after crimping a terminal, to help ease the situation, use a dab of dielectric grease to prevent the two silicone components from binding up.  If the above-mentioned tool...  If the above-mentioned tool is out of the question...  ... you can still achieve...  ... you can still achieve a production-type crimp with the vice-mounted mini crimpers most manufacturers supply with high-performance wire sets.  Once cutting and fitting wires...  Once cutting and fitting wires is done and out of the way, no matter how you ultimately route said wires from the spark plugs to distributor cap, use some sort of separating device to prevent any possible crossfire or arching.  Typically, choices for popular...  Typically, choices for popular plug wire (7, 8, and 8.5 mm) separators are nearly unlimited, however, if you happen to find yourself installing a set of the mini 5mm Ferro-Siral wires, you don't have many choices to begin with-that's where creative thinking comes in!  Don't let all your hard work...  Don't let all your hard work making and installing a brand-new plug wire set go to waste by ripping a terminal from its connection (often the result of pulling from the wire "behind" the crimped terminal).  Do yourself and your wires...  Do yourself and your wires a favor-grab a handy plug boot remover at the local auto parts store next time you're buying plugs or oil. They're only a couple bucks, which is a nominal price to pay for insurance against having to replace a terminal.
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