Timing Magnetos 101: A Beginner's Guide

Timing magnetos are a crucial component in many classic cars and motorcycles, responsible for generating a high voltage to spark the engine's ignition. They're a vital part of the ignition system.

A timing magneto is essentially a small generator that converts mechanical energy into electrical energy. It's connected to the engine's crankshaft and rotates with it.

The magneto produces a high voltage, typically between 5,000 to 15,000 volts, which is then sent to the spark plug to ignite the fuel. This voltage is strong enough to jump the gap between the spark plug electrodes.

In order for the magneto to produce the correct timing, it needs to be precisely aligned with the engine's crankshaft. This is typically done using a timing pointer or mark on the magneto and engine.

There are three main types of magnetos: AC, DC, and magneto-ignition.

AC magnetos produce a higher voltage output, typically between 6 and 12 volts, and are often used in high-performance engines.

DC magnetos produce a lower voltage output, typically between 1 and 3 volts, and are often used in low-performance engines.

Magneto-ignition magnetos produce a high voltage output, typically between 6 and 12 volts, and are often used in high-performance engines.

Improper timing can lead to engine damage, including destructive detonation, which can cause major internal damage. This is most commonly caused by timing that is too far advanced.

Detonation can be caused by low octane fuel, but if you stick to avgas, you should not have fuel-related detonation problems. Most four-cylinder Lycoming engines should be set to 25° before top dead center.

Timing does not advance itself over time in a good-running engine, but it can drift due to worn parts. The follower on the points is a common culprit.

A 500-hour inspection is recommended to check for wear on the points, especially on Slick magnetos. This can cause the timing to retard itself, leading to power loss.

Power loss can be subtle, but it can be detected in diminished climb performance or longer-than-usual takeoff rolls.

Take a look at this: Magnetos Power

The timing magneto is responsible for providing the spark that ignites the fuel in your engine, making it a crucial component in the combustion process.

Most engines use a timing magneto to ensure the spark plug fires at the right time, which is typically between 10 to 40 degrees before top dead center.

The spark plug fires when the piston is in the correct position, allowing for maximum efficiency and power.

In a typical 4-stroke engine, the piston moves up and down in a cycle of intake, compression, power, and exhaust.

The timing magneto ensures the spark plug fires during the power stroke, when the piston is moving down and creating the most power.

This precise timing is critical to the engine's performance, as it affects the amount of power and efficiency the engine produces.

The timing magneto's spark timing can be adjusted by turning the magneto's adjustment screw, which is typically located on the magneto itself.

Adjusting the spark timing can help fine-tune the engine's performance, but it's essential to consult the owner's manual or a mechanic for guidance to avoid damaging the engine.