The ignition system is important in creating a spark that will ignite the fuel-air mixture in the cylinder of the engine. The timing is very important, at exactly the right instant at the correct rate, for the engine to run perfectly. A component of the ignition system is the distributor which is the device that routes high voltage from the ignition coil to the spark plugs in the correct firing order. The distributor has a rotor inside the distributor cap, on top of the distributor shaft. The distributor cap is the device that distributes electricity from the ignition coils to the spark plugs at the right timing. It is usually made of hard plastic and a small amount of copper. The rotor inside the distributor cap rotates as it receives current from the ignition coils and passes it on to the copper portion of the cap. Then the current is passed on to the spark plugs. The distributor cap covers the distributor as well as the rotor. It has one post for each cylinder and a terminal inside the cap corresponds to each post. The plug terminals are arranged around the circumference of the cap in the correct firing order in order to send the secondary voltage to the proper spark plug at the right time. Possible causes of distributor cap's failure are vibration and heat, a crack in the bakelite housing and carbon deposit accumulation. Contamination or a crack in the distributor can cause the vehicle to falter during its acceleration. Your Ford distributor cap should be changed during tune-up or every two years. An easy way to check if you have a bad distributor cap is by checking if you can see sparking between the electrodes on the cap when the engine is running. Check our online store where we have a selection of distributor cap replacements you can choose from.