Actually you are all making good points here about ballast resistors but there is additional historical information that may be interesting and insightful.....I
n the early-to-mid fifties Detroit began introducing more powerful engines. Chrysler had their famous Hemi, while GM and Ford also introduced high-compression OHV V-8's. The horsepower race was on and many of the ideas were gained from the engine advances of Word War II (piston-powered) aircraft.
When you increase the compression and number of cylinders it becomes a more difficult challenge to start engines, using the traditional Kettering 6-volt starter system. (BTW, Kettering is the same guy who pioneered the battery-Ignition-using coil-points-distributor to replace the magneto.)
the 1954 - 1956 timeframe most Detroit engineers began upgrading electrical systems from the traditional 6 volt systems to the now standard 12-volt systems. If you understand Ohms Law, ( E = I * R, see: http://www.the12volt.com/ohm/ohmslaw.asp ) increasing the potential voltage offers several significant advantages.
When automotive electrical systems were moving to 12-volt designs, some bright engineer discovered you could continue to use existing 6-volt coils in combination with a relatively inexpensive ballast resistor. Adding the 'BYPASS" circuit to the starter also gave the beneficial short-term "BOOST" for lighting off the higher compression engine. After the engine was done cranking the coil and points could revert to operating closer to it's earlier 6-volt design limits. Since the ballast resistor acts to limit electrical current to the primary side of the coil and thru the contact breaker points before returning to the battery via the common ground path, the life-cycle of all components in the chain is extended. But not all Detroit manufacturers used external ballast resistors -- some incorporated the resistor inside the coil.
Once you move into the early to mid-seventies when long-term emissions began to be a concern we started seeing the adoption of breaker-less or electronic ignition (EI) systems. The famous GM HEI system incorporates the coil and distributor into one unit. And permits higher secondary voltages, which allows greater spark plug gaps,
The Pertronix breaker-less EI products (Ignitor, Ignitor II, Ignitor III) can be combined with their various Flame Thrower Coils. see: http://www.pertronix.com/prod/ig/flame/coils/chart.aspx<http://www.pertronix.com/prod/ig/flame/default.aspx>
I've used the Ignitor II EI with an internally ballasted Petronix 45,000 volt coil for the past three-seasons, with excellent results. I have retained the original Mallory (marine-rated) distributor, but no longer have a need for the OE ballast resistor. The system retains a stock look, but provides modern HEI efficiency and long-term, hassle-free reliability,
History class is now dismissed......;-)
Lee
Received on Thursday, 13 May 2010
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