Re: Internal or external resistor required ignition coil on a
Posted by HH56 On 2022/1/3 20:21:30
For what it is worth, the 29 drawings do not show any external resistor. While the drawing does show the coil internals, it is hard to tell from the drawing if there might be a resistor inside the coil but typically 6v coils did not require or have one. On a modern universal 6v coil I would not recommend using a resistor because that might make the spark too weak to reliably jump the plug gap.
12v coils use some type resistance because most often the coils are designed to work at approx 8-9 volts so as not to overheat. Working at the constant lower voltage also allows circuitry to briefly provide a separate voltage to the coil directly from the battery to sort of counteract the voltage drop due to the heavy current required by the starter motor during cranking and provide a stronger spark.
As to the ignition switch, depending on type the modern designation for terminals would be BAT, IGN and ACC. BAT would be the supply in and IGN would go to the coil only while ACC would supply everything else. For the separate from coil stock Packard switch until 54, their usual designations were AM, GA and COIL. AM corresponds to BAT, GA to ACC, and COIL to IGN. If the switch has only a single on position both IGN and ACC terminals are active but in a switch with a right and left position, ACC will be active in both while IGN is only hot in the right side or the typical run position. If there is an accessory such as a fuel pump that is only wanted to be on when the engine was running that would also be powered from the IGN terminal.
Here is the wiring details from thje 1929 AEA drawing available at the PAC site.
Attach file:
29 drawing.jpg (160.61 KB)
12v coils use some type resistance because most often the coils are designed to work at approx 8-9 volts so as not to overheat. Working at the constant lower voltage also allows circuitry to briefly provide a separate voltage to the coil directly from the battery to sort of counteract the voltage drop due to the heavy current required by the starter motor during cranking and provide a stronger spark.
As to the ignition switch, depending on type the modern designation for terminals would be BAT, IGN and ACC. BAT would be the supply in and IGN would go to the coil only while ACC would supply everything else. For the separate from coil stock Packard switch until 54, their usual designations were AM, GA and COIL. AM corresponds to BAT, GA to ACC, and COIL to IGN. If the switch has only a single on position both IGN and ACC terminals are active but in a switch with a right and left position, ACC will be active in both while IGN is only hot in the right side or the typical run position. If there is an accessory such as a fuel pump that is only wanted to be on when the engine was running that would also be powered from the IGN terminal.
Here is the wiring details from thje 1929 AEA drawing available at the PAC site.
Attach file:
29 drawing.jpg (160.61 KB)
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