TI ignition resistor values
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Le Mans Master
Joined: Dec 2006
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More food for thought:
In a pinch I don't see any obvious problems going with R7=.4 ohms, and R8=.68 ohms. (Either choice of the two sources still ends up with a series total harness resistance of almost 1 ohm exactly.) My preference for the above arrangement is two fold. Better circuit operation at low battery instances (more electrical headroom for the circuit board components due to less voltage drop across R7), and during cranking (when the starter solenoid wire shunts R7, the higher resistance of R8 (.68 vs .43) helps keep the coil current from going to the moon.
This theory may have been over ruled by real world issues.IE., it fried the board or the pick up coil, so they reversed the values to keep the total circuit resistance to approx. 1.1 ohms.
In a pinch I don't see any obvious problems going with R7=.4 ohms, and R8=.68 ohms. (Either choice of the two sources still ends up with a series total harness resistance of almost 1 ohm exactly.) My preference for the above arrangement is two fold. Better circuit operation at low battery instances (more electrical headroom for the circuit board components due to less voltage drop across R7), and during cranking (when the starter solenoid wire shunts R7, the higher resistance of R8 (.68 vs .43) helps keep the coil current from going to the moon.
This theory may have been over ruled by real world issues.IE., it fried the board or the pick up coil, so they reversed the values to keep the total circuit resistance to approx. 1.1 ohms.
