[koates]

Hi there. When measuring the voltage at the original Ford ignition coil with the engine not running, then the distributer timing contacts must be closed so that the coil circuit is energised. When doing this test you have to be quick, as in just a few seconds after turning the ignition switch ON from COLD. In this case you should get about 4 volts at the coil. The longer the ignition switch is left on then the more the resistor heats up thus increasing its resistance and lowering the voltage at the coil. If the ignition switch has been ON for a minute or two or three then you may have only about 2 volts at the coil. Remember this is with the engine not running. Voltage readings with the engine running would be higher than this. The resistor is designed to give a higher voltage at the coil when cold so as to give a better spark at the spark plugs when cranking for the first start up from cold. Once the engine starts and the resistor warms up thus reducing the coils current draw and therefore making for a longer life of the distributer contacts. A great simple system which seems to be so misunderstood. The original genuine FORD resistor is the best one to use as it has the correct type of wire in the winding. Other reproductions may or may not have the correct wire and therefore may not work as they are supposed to. Regards. Kevin.