staggered ignition

staggered ignition

A dual ignition timed so that the spark plug nearest the exhaust valve fires before the spark plug nearest the intake valve. This is to ensure that the fuel-air mixture is diluted by partially burned exhaust gases (which burn more slowly than a normal mixture) and is ignited first.
An Illustrated Dictionary of Aviation Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved