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June 28, 2004
The typical function of a resistor in either the coil as in built in, special resistance wire to the coil or with one in series between the power supply and the coil is this.
When the resistor is cold, it passes a lot of current so the cooil will have about full voltage at start up to produce a hot spark. As the resistor heats up, it reduces the amount of power getting through, so instead of a full 12 volts, for example, it now is passing only 9 volts or so. The coil will still produce a full spark, but it will be running a bit cooler in the process.
This is an old solution to extending coil life. Fords from the early 30's had a resistor to cut the running voltage to the coil down to 3 volts from the normal 6. Sometimes when the engine stalled while hot, they were unable to start again. The knowing driver lifted the hood, shorted the resistor terminals with a penny, got full voltage to the coil, engine started!
And if you think that the new cars that have a coil for each spark plug is brand new technology, this was the way Model T Fords were made! All this is before my time, but I love history!! LOL!
Paul A
"Paul Asgeirsson" < PAsgeirsson@... > 32800
Posted on June 28, 2004 04:21 PM
Posted to category(s) Body | Cooling System | Electrical System | Engine (external) | Engine (internal) | Ignition System | Lubrication System | Suspension & Steering | Tuning
