Expert: Brad Sears - 7/20/2009

Question
I am getting power to the coil with continuity through the coil and to the capacitor.  The capacitor does not show continuity.  The needle on electric meter goes up little and goes back with the polarity in both directions. The needle shows fluctuation when connected to the terminal of breaker points, but there is no spark at the spark plug. I have used both the original coil and a new coil with the same result.

Answer
The capacitor only has continuity for a nano second when current is applied to it as it stored electrons on each plate. So unless you have an old capacitor tester you will not see a reading on your meter. The terminal on the top of the coil should see power when the ignition is on. There is a resistor under the dash right over the brake and clutch pedal that controls the current to the coil. When the points are closed and the current is flowing and the points are closed the voltage will drop to 4 or so volts and then increase to battery voltage as the engine turns over and the points open. The most common problem is burned points. They can be inspected once the distributor is removed and they can be replaced and adjusted without special tools. the ford flat heads used a dual point system and it is important that they be set accurately with a feeler gage.
Brad