Condensers and Coils

Condensers:  You can tell when a condenser has gone bad if your normally smooth running engine suddenly backfires and won’t rev up.  One way of checking this out is to remove the distributor cap, body and rotor.  Make sure the points are closed.  Turn on the ignition switch and place the high tension wire (from center of coil) about 1/2” from any convenient ground on the engine.  Push points open with a screwdriver then close the points.  The spark should jump the gap with a sharp crack and a straight line.  The spark should have a blue tinge.  If the condenser is bad, the spark will still jump the gap, but will be thin and stringy and white in color.  Whenever in doubt throw the condenser away, especially if it is a new reproduction condenser.  These cannot always be depended on.  If you happen to have  used condensers and want to have their condition checked, take them to your local TV or radio repairman who has the necessary equipment to check them.

Coils:  Begin by turning off the ignition key.  Remove the tension wire from the center point on the coil.  Remove the black wire from the terminal (- side) on the coil and the red wire on the (+ side) of the terminal on the coil.  Using an ohmmeter (lowest scale), measure the resistance from the (+) coil terminal.  This should measure 1.6 ohms to 1.8 ohms.  Now set the ohmmeter to 10K scale.  Measure the resistance from each coil terminal (+) and (-), to the center contact.  This should measure 6.7 ohms to 10K ohms.  Measure the resistance from each coil terminal (+) and (-), to the outer metal case of the coil.  Now you should measure as an open circuit.  If the first two steps show a short or open reading, it indicates a defective coil.  If the 10K step shows any reading except open (infinity), the coil is defective and should be replaced.

This tech tip was originally printed in the September 2000 “A” Quail Call.

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