Editing Distributor (section)

=== Ignition advance ===
In older distributors, adjusting the [[ignition timing]] is usually achieved through both ''mechanical advance'' and ''vacuum advance''. [[Ignition timing#Mechanical timing advance|Mechanical advance]] adjusts the timing based on the engine speed (rpm), using a set of hinged weights attached to the distributor shaft. These weights cause the breaker points mounting plate to slightly rotate, thereby advancing the ignition timing. [[Ignition timing#Vacuum timing advance|Vacuum advance]] typically uses [[manifold vacuum]] to adjust the ignition timing, for example to improve fuel economy and driveability when minimal power is required from the engine.

Most distributors used on [[electronic fuel injection]] engines use electronics to adjust the ignition timing, instead of vacuum and centrifugal systems. This allows the ignition timing to be optimised based on factors other than engine speed and manifold vacuum.
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