Occasionally we are contacted by both installers and vehicle owners who tell us that an engine on which they have installed Magnecor ignition wires is misfiring, and they see sparks jumping from the boots or cable jacket.

In almost every instance the problem is caused by improper installation of the wires and/or bad termination of universal wires. Also, a failed or excessively gapped spark plug, a cracked or condensation-laden (inside) distributor cap or a cracked ignition coil tower can cause arcing that seems to come from the ignition wires. Sometimes, a silicone rubber spark plug, distributor or coil boot is cut by something sharp (usually during installation). Any of these problems causes spark energy to find it easier to induce itself to the outside of the cable jacket and/or boots, as well as arcing over the inside of moist distributor caps and coil towers in preference to jumping the spark plug gap. Also, the distributor cap and/or coil could have been damaged (cracked or burnt) by failed conductors in the previous ignition wires burning back inside the cable insulating jackets or by failed solid resistor connectors used on European ignition wires.

Often, on some Chrysler vehicles, the ignition coil has been changed by the previous owner to a non-Chrysler coil, and unless we are made aware of this situation, the coil lead we supply in sets will only properly fit a Chrysler coil. It’s possible to loosely fit conventional coil leads into Chrysler coils, and forcibly fit Chrysler coil leads to conventional coils — however in most cases arcing will occur! This is only a problem on certain Chrysler vehicles sold in USA from 1978-1991

The first step needed to solve an arcing problem is to ensure the terminals inside the spark plug and distributor boots are properly engaged. Damage can occur if the engine has run long periods with wires not properly connected, although in most instances when using Magnecor Race Wires the damage at the spark plug end is usually confined to the spark plug top if the ignition wires incorporate one piece rubber type spark plug boots.

On certain engines (mostly of Japanese origin), using ignition wires that include multi-part hard plastic extension type spark plug connectors, the all-too-common problem of moisture from condensation accumulating in un-drained spark plug holes can terminally damage spark plug connectors because arcing will occur over the wet plastic extension tubes and bottom seals. Sometimes, if excess moisture is allowed to fill up spark plug holes, arcing will occur even if one piece silicone rubber boots are substituted for the original multi-part hard plastic extension type connectors. Owners of these cars (the Ford Taurus SHO, recent Ford Escort GT and Mazda Miata engines being the most prone) should be aware that washing down the motor can also contribute to this serious problem, as the top covers of the spark plug connectors (which appear to be used to keep water and dirt out) have air vents. Also, the vents cause condensation from the air (particularly in areas by the sea) to accumulate inside the spark plug holes even if you don’t wash your engine or drive your car in the rain. The best cure for this problem is to carefully remove the spark plug connectors and remove all moisture from the spark plug holes with either compressed air (wear eye protection), a shop vacuum or by absorbent paper towels if your car has traveled through a wet season, you wash down the motor regularly or live in an area where condensation noticeably accumulates over the engine (usually during the night as a hot engine cools down). At the same time it’s a good idea to check if oil (usually from leaking valve covers) is also present, as the presence of oil will make a bad situation even worse. Photographs indicating what you may see if you have moisture or oil in the spark plug holes can be seen in some of Magnecor USA’s Technical Bulletins.

Another problem we encounter from time to time is arcing from multi-part hard plastic extension type spark plug connectors when original screw-on metal spark plug tops (nuts) are replaced by taller tops that keep the bottom connector seals too far above the normal sealing position. Although these taller tops are included in Bosch spark plug boxes presumably to allow the spark plug to be used on a multitude of engines on which taller plugs were originally used, these taller tops are often used to help solve the problem of the spark plug connectors vibrating or shaking loose on engines which have a balance or mount problem. If your spark plug connectors are continually coming loose, please advise us at the time you order a Magnecor wire set, as usually we can supply you with modified connectors which can decrease the number of times the connectors vibrate or shake loose — although more care will have to be taken when later removing the connectors.

Also, please read this important note about spark plug heights! If you are experiencing a problem, and you think the wires have not been properly connected for many miles, you should examine the spark plug tops for burning — as to simply re-fit the ignition wires to the damaged spark plug top could cause the terminal inside the spark plug boot to either lock onto a rough burnt surface or be so loose on a burnt-away top that no proper contact will be made. Whenever either, or both, an ignition wire’s spark plug end and distributor end metal terminals are not properly engaged the spark energy needs to jump an additional gap on its way to the spark plug gap inside the pressurized combustion chamber. Because spark energy always finds the path of least resistance, that path may be an induced path outside the cable jacket situated near a grounding point or from the inside of a loose boot in preference to jumping the spark plug gap under pressure plus the additional gap created by the loose connector. The potential of spark energy being induced from the conductor inside any or all spark plug wires to the outside of the insulating jacket or boots (and sometimes into an adjacent wire) is the reason why it’s so important to space all spark plug wires from one another and away from both metal surfaces and coolant hoses, particularly if your engine is a race or modified engine that will generate high combustion chamber pressures, and/or will be using fuels that are difficult to fire, and also if a spark plug fails.

It never ceases to amaze even the experts how readily the spark from an automobile ignition system can find an unusual path of least resistance — particularly when it wants to jump a 25mm or more free air gap in preference to firing a failed or excessively gapped spark plug inside the pressure of a combustion chamber!

If Magnecor Race Wires are used on an unmodified production street engine with a stock ignition, the importance of spacing spark plug wires is less important. Generally our KV85 Competition wires (8.5mm cable size) will fit into the original equipment wire holder/separators because the silicone rubber jacket is extremely flexible and tear resistant.