Doug Anderson wrote:
>Hello Tom, long time, no talk... -been very busy. So much so that I can't
>hardly keep up with the many interesting subjects on our list. I've caught
>a little of the chatter about secondary resistance -but not enough to fully
>understand what you fellas were driving at.
Doug,
Good to hear from you. I will attempt to explain what the resistance in
the secondary circuit is meant to do. At least my understanding of the
subject.
I guess it was in the fifties that most manufactures introduced
resistance in the secondary circuit. There were three popular methods of
getting the resistance in the circuit, Plug wire, spark plugs and
ignition rotors. Of course in those days the first thing that we did, if
we were looking for performance, was to install a new set of Packard 440
wires and get rid of the resistor plugs or rotor.
I remember that Corvettes were a problem because they did not have a
steel firewall to help block the electrical noise. Even the metal
shielding which they used did not do a very good job with non-resistor
wires. If you got rid of the resistor wires, the ignition noise in the
radio became a big problem. We corrected that by using the resistor
rotor. Speaking of radio noise, some of you may remember the grounding
washers used on the GM products that were using the ball type front
wheel bearings. (Remember the slogan, "Nothing rolls like a ball"?) This
brass or copper spring washer made contact with the end of the spindle
and fit inside the front wheel dust cover to facilitate a ground to get
rid of the static electricity.
Secondary voltage is AC current, which means it cycles between negative
and positive. With non-resistor circuits, when the spark is delivered
from the distributor to the plug, it strings out and continues to cross
the gap of the plug, after it has fired the mixture, until there is no
longer sufficient voltage to jump the gap. When resistance is introduced
into the circuit the voltage has to build to the point of overcoming the
resistance to travel across the plug gap. This accomplishes two things,
first, the voltage flow is restricted so as to reach the plug gap all at
once producing the spark and leaving little residual voltage. What is
left is too weak to cross the gap, so it dissipates. Second, (this gets
back to tractor deal I mentioned earlier) in the secondary circuit, the
voltage will only rise to the level required to fire the plug. It
doesn't matter how much voltage is available only the voltage required
to overcome the resistance in the circuit will be used. Therefore, when
resistance is added to the secondary circuit a higher voltage reaches
the spark plug which will produce a stronger spark.
I hope this is helpful, I don't know of anyone today that does not
recommend using a good resistor wire on performance engines.
Tom, Redding CA - #216 D/GCC
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