Ken,
There are basically three types of ignition wires:
Solid Core - typically for racing only on carb'd racers..
Suppression Core - Carbon Impregnated Rayon Cord.
Suppression Core - Spiral wound.
Spark Plugs - either standard or resistive core.
The function of the resistance is to reduce the RFI (Radio
Frequency Interference) generated by the high voltage of
the ignition system. This interference can disrupt any radio
reception, or even cause problems with modern Engine
Control Units.
The problem with the carbon impregnated suppression wires
is that with age the resistance increases, decreasing the voltage
to the spark plugs. Eventually one of more of the plugs will not
fire at all (you need spark the most under heavy loading and
starting conditions, so this is when you first notice the wires are
starting to go bad).
The wire wound suppression wires have the best of both worlds
Solid wire wound in a spiral pattern for high inductance. You still
deliver full voltage to the spark plugs, but with good suppression
of RFI. I remember NGK sold these wires, noticeable as they
were a translucent blue so you could actually see the spiral wrap
of the wire.
Accel sold the "high performance" carbon impregnated wires in
large diameter for longer life and better performance. I still have
a set on my '68 2000. I usually would buy a "universal V8" set
of spark plug wires... same price as the four cylinder set, yet
I could get two sets of plug wires out of that box, as long as
I reused a coil wire end caps!
Typically the resistive spark plugs came in to use with a "solid"
wire, yet still be able to listen to a radio. Perhaps resistive plugs
first appeared in the later half on the 1970's?
Quick check:
Solid core wires.... 0 ohms (I no longer use them)
NGK Blue wires... 0 ohms
Accel Yellow Jacket Silicon Suppression wire: 3K per foot*
OEM wires, about 4K Ohms per foot.
OEM Toyota wires, about 4K Ohms per foot.
*wires are over 10 years old.
So back to answer your question... if you roadster wires are
around 120K each... toss into the trash AFTER you get a new
set of wires. I seem to recall NGK did not have anything for
roadsters, but I was able to use a set for a "A15 fitted Datsun 210"
model from the mid 1980's. Coil wire was a little long, but rest
of the wires worked fine (distributor is in about the same location).
Little long winded on the reply, but just in case....
Cheers,
Tom Walter '68 2000
Austin, TX
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