> -----Original Message-----
> From: jon@dakota-truck.net
>
> "ctandc" <ctandc@comcast.net> wrote:
>
> > Spark plug wires are a maintenance item.
>
> Yes, but the information I am looking for is *why* they are a
> maintenaince item.
Ok Jon, here's how "wear" can occur. Heat, oil, grease, dirt, vibration,
load, and design. Different brands of wires have varying types of
conductors, insulation and quality of terminals (and their attachment
method). This makes some more susceptible to wear than others.
The wider gap one uses on their spark plugs (either on purpose or due to
wear), or the higher energy ignition system one uses, the greater the "load"
on the conductor.
Not only can resistance increase over time/use, the conductor (or terminals)
may separate, resulting in basically an electrical "open" in the circuit.
This can occur from vibration, heat, load or age. This can sometimes be
overcome by the ignition energy but the wire is still not "good" at that
point. This could be caught by a resistance check with a volt/ohm meter.
Sometimes a consumer my cause his own problems by pulling on the cable
rather than the connector/terminal/boot when attempting to change plugs.
There are handy tools available (cheaply) to help one properly remove a
wire/boot from a plug.
My tips for getting the longest life out of plug wires...buy a quality brand
with spiral wound conductor, keep your engine (and wires) clean, secure the
wires at multiple locations to reduce vibration, and gap your plugs no
greater than .005 or so above factory specs. Oh yeah, don't neglect to
change (or at least re-gap) your plugs at the factory recommended intervals.
BTW, I always do a resistance check on new wires before I install them and
over the years have found one new wire that was not conductive (i.e.
"open"). If you do this you will have a baseline for checking them again
after a couple years of use.
> only replace a wire when it is "all used up", as they say. :-)
>
> --Jon-
My brother-in-law used to do that on his mustang. He would find a bad wire
and replace only that one. Problem was, one after another soon failed and
eventually he realized it would have been cheaper and less time consuming if
he had replaced *all* of them when the first one failed. :-)
Ray
http://www.dragtruk.com/ENTRIES/20KM1FD2KWBP.html
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