Distributor cap

Distributor caps and rotors are responsible for passing the voltage from the distributor cap coils to the engine's cylinders in order to ignite the fuel-air mixture inside and power the engine. The coil connects directly to the rotor, and the rotor spins inside the distributor cap.

A distributor cap is a removable component that is used in spark ignition systems to cover both the distributor and the rotor. In addition to covering these components, and protecting them from contamination, distributor caps are also responsible for helping to distribute electrical current from an ignition coil to a set of spark plugs. Since distributor caps are wear items, they have to be replaced periodically as they wear out. A distributor cap contains internal contacts and corresponding external posts. Although distributor cap designs can vary from one application to another, they all share a few basic components:. The main body of a distributor cap is typically made from molded plastic that has a number of metal components built into it. A typical cap has one metal contact and post per cylinder and one central contact and post for the coil.

Distributor cap

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The central contact is typically a spring-loaded carbon brush that mates with a central contact point on the rotor, which allows it to remain electrically connected while the rotor is spinning, distributor cap. Another variation is found in vehicles that distributor cap two spark plugs per cylinder. More Articles.

A distributor is an electric and mechanical device used in the ignition system of older spark ignition engines. The distributor's main function is to route electricity from the ignition coil to each spark plug at the correct time. A distributor consists of a rotating arm 'rotor' that is attached to the top of a rotating 'distributor shaft'. The rotor constantly receives high-voltage electricity from an ignition coil via brushes at the centre of the rotor. As the rotor spins, its tip passes close to but does not touch the output contacts for each cylinder.

Although distributors are not common in modern vehicles, a distributor cap on older model vehicles connects the spark plug wires and distributor, and also protects your distributor's internal components. Distributor caps feature metal contact points on the underside, and when they are contacted by the rotor, this links the ignition coil's voltage to the proper spark plug to provide the power needed to create a spark. This is timed appropriately to ensure the rotor connects power to the spark plug at the appropriate time for combustion. With time, a distributor cap and its contacts may wear and fail under the stress of constant exposure to high voltage. If the distributor cap's contact points are worn down enough, it may not contact the rotor consistently, which can cause misfires or failed starts. The distributor cap may also be damaged or crack, which can allow moisture into the distributor housing and lead to corrosion or other damage. If you notice trouble starting your vehicle, a tapping, sputtering, or clicking sound, or engine misfires, check your spark plugs, wires, distributor cap, and distributor rotor for signs of wear, and replace these parts if needed. Distributor cap and rotor replacement are also often considered part of a regular tune-up, along with replacing the spark plugs and spark plug wires, and a tune-up can often restore performance and efficiency. When you're ready for a tune-up or ignition repair, O'Reilly Auto Parts carries spark plugs, ignition coils, and replacement distributor caps and rotors, as well as the tools and supplies you may need to get the job done.

Distributor cap

Distributor caps and rotors are responsible for passing the voltage from the ignition coils to the engine's cylinders in order to ignite the fuel-air mixture inside and power the engine. The coil connects directly to the rotor, and the rotor spins inside the distributor cap. When the rotor's tip passes a contact on the cylinder, a high-voltage pulse travels from the coil to the cylinder via the rotor. That pulse jumps the little gap between contact and rotor and moves on to the spark plug wire, eventually igniting the spark plug on the cylinder. Because of all the high-voltage activity, the rotor and cap have to be replaced relatively frequently.

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In order to account for this, distributor caps in waste spark ignition systems have half as many internal contacts as there are cylinders in the engine, and each contact is tied into two posts. Automotive News Turn signals on a car's touchscreen? Instrumentation What is a Fuel Gauge? Mobile Newsletter chat avatar. What is Brake Fluid? How a Car Works. When a distributor cap is installed, it has to be lined up correctly on the distributor. The central contact is typically a spring-loaded carbon brush that mates with a central contact point on the rotor, which allows it to remain electrically connected while the rotor is spinning. Distributor cap. Opening the points causes a high induction voltage in the ignition coil.

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By: HowStuffWorks. Our launching Remax product range contains more than parts, covering the years Fast Delivery - Products in stock for same day dispatch. In any case, a distributor cap failure is typically rectified by simply replacing the component. This section needs additional citations for verification. Portal Category. Therefore, the real catch to the coil-distributor-cylinder system is timing. These weights cause the breaker points mounting plate to slightly rotate, thereby advancing the ignition timing. A few signs of a faulty distributor cap include difficulty starting your car, shaking, stalling and hearing a yelling noise. A distributor cap contains internal contacts and corresponding external posts. Since there's a short delay between when the spark is created and when it ignites the mixture in the cylinder, the spark has to happen before the piston reaches the top of its stroke.