Spark Plug Wires

Are replacement wires even necessary?

No, as long as you are not having any problems. But, if you are looking for that last ounce of performance, dependability and you have installed UltraPower then yes they are worth the cost along with a set of AC Delco plugs.

If you are going to try to justify the cost of the updated wires and the AC Delco plugs on increased HP/TQ and/or gas mileage then you are going to be very disappointed. The HP/TQ will only show up on a dynamometer and the mileage increase, if any, would be in the .1 or .2 mpg under the very best conditions.

I did do some research on various brands such as Accel, MSD, Bosch, AC Delco, Taylor, Moroso and Magnecor. There are others but after looking at the specs and the like I found they are all pretty much the same.

Size - Diameter

  • 7mm is pretty much stock size.
  • 8mm to 8.5mm is the next commonly available size.
  • 9mm is in the High Performance or Race type wires.
  • 10mm or 10.4mm seems to be the largest available.

Magnum Plug Wires

My good friend and mentor, Glen Norman, worked with a specialty manufacturer of spark plug wires and came up with the Magnum Plug wire. This plug wire is straight out of NASCAR. You can not buy these wires from any retail outlet. They are made exclusively for Oemy's UltraPower & Brazel's RV Performance.


  • Stainless Steel Core
  • Silver plated wrapped Copper conductor
  • Mercury Maine Style Plug boot
  • Ferrite EMI/RFI Collar
  • Large 10mm Diameter wire cover
  • 0 Ohms
  • Limited Lifetime Warranty

Are they better than Taylor's or any other brand? Yes
Will they eliminate the burn plug wire problem. No. Why? The bunrt wires are cause by poor air flow to the back 4 cylinders of the engine. This is usually casued by the RV manufacturer design issue of the air intake or grill area.
The Magnum wires will not break down as they have a stainless steel core and not a carbon core that breaks down due to the heat.

Are there special requirements? Yes
The OEM Heat Shields must be installed.

Taylor 409's & Stock AC Delco's

Some of the specs/terms used in the construction are:


  • Fiberglass braid
  • Kevlar inner core
  • Ferrite EMI/RFI
  • Copper/Nickel Conductor
  • Spiral Wound

Boot Material

Just about all OEM's specify Silicone and Stock style boots. If they don't use stock style boots you probably will not be able to use the metal boot covers that are on the stock wires.

Temperature Range

Just about all of the wires reviewed with withstand temps to 600 degrees and some as high as 1000 degrees for a short duration. If you add protective boot covers this will increase the temp rating to 1200 degrees.

Wire Resistance

This number is usually measured by the foot. In the case of the 8.1L the wires are about 1 foot long. Most OEM's don't provide this info unless it is very low. The lowest I have seen is 40 ohms per foot. The theory here is the lower the resistance the better the spark.

Taylor TV50's

Taylor 409's

Boot Protectors

These boot covers offer addition heat protection up to 1200 degrees. IE - High heat for a short duration. They are not intended to resolve burnt plug wires do to poor cooling of the engine because of restricted air flow/circulation.

Most are made from some flameproof material such as heat-treated fiberglass, Nomex, Kevlar or some combination of materials.

Most are 1" x 6" double layer. Some are as small as 3/4" x 6" or as large as 1" x 8". The new Taylor boot covers that come installed on the Extreme Service plug wires are 1" x 8.5". This makes them the largest of any I have seen.

The "Boot Protectors" cost will vary depending the manufacturer, size and what material they are made from. You can get them in various colors. But, be aware that the color in many cases is just high temp spray paint.

Taylor Boot Protectors

I installed a set of Orange Taylor Boot Protectors on my Taylor TV50's.
Note - These covers are the same as the Silver version but with a heat resistant coating.

Old Style Taylor Extremes

Taylor has changed the length of the boot cover that goes over the the plug boot by almost 2.5". This is a real bonus for those that have a heat problem. But, there is a downside also. The cost has gone up and the install may get difficult do to the space the cover takes.

New Style Taylor Extremes

The Bottom Line

Of all the wires and plugs I have installed I hear, "It runs smoother", "It sounds better", "It idles better", "It has better throttle response". Now are these perceived improvements or actual improvements? I don't know and trying to prove them wouldn't be worth it.

Should you decide to add the boot covers after the fact be aware that they may not fit over the coil boot or the plug boot making it impossible to install on exsiting plug wires. The Taylor boot covers have a steel ring in the cover that is only slightly large than the plug wire.

After digesting all this info I plan to stick with Taylor wires as the stock AC Delco wires are only 7 mm and 1000 ohms per foot. Overall Taylor wires provide a very good bang for the buck. There are 2 versions of their 10.4 mm wires that you may what to consider, Taylor TV 50's and 409's. The only difference is the TV 50's are of lower resistance than the 409's, 50 ohms per foot versus 300 ohms per foot. Of course the TV 50's are more expensive.

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