angle of advance

noun engineering

the angle in excess of 90° that a steam-engine valve gear is in advance of the crank
the angle between the point of ignition and bottom dead-centre in a spark-ignition engine

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012