Resistor Selection
Ford Front Mount Coil

The following tabulation will help you determine which resistor is needed for the various coil / voltage combinations used on early N-Series Ford tractors with the front mount distributor.

"V @ Coil" is useful in determining if the correct resistors are installed. Note: V @ Coil is dependent on breaker point condition and the electrical connection between the coil pigtail and the breaker plate screw. If the points are burnt or if the pigtail connection is marginal, V@ Coil may not provide any useful information.

*Resulting voltage after resistor(s) are at operating temperature.

• "OEM' refers to the original factory resistor which attaches to the terminal block. The New Holland part number is A8NN12250B
• The numbers in parenthesis are the nominal resistance values (ohms) at operating temperature. Actual resistances may vary significantly due to temperature and manufacturing tolerances.
• RU4 and RU6 are Borg-Warner part numbers. The coil resistance is for the primary winding and is measured with the coil removed from the distributor.
• V @ Coil is the voltage measured at the coil terminal with the ignition switch ON, the engine not running, and the points closed. Allow at least one minute for resistor to reach operating temperature before taking voltage readings.
• V@ Coil is based on used breaker points in good condition. If new breaker points are installed, V@ Coil may be lower than the ranges shown here.