Occurrence of Preignition in Present-Day Cars in Normal Service

PREIGNITION is defined by Mr. Winch as the initiation of a flame front by some means other than the spark discharge at some point in the combustion chamber prior to the arrival of the normal flameat that point. He believes that wild ping is actually a combination of preignition and knock.

His study of both 1952 and 1953 cars indicates that preignition has become a very serious problem. Moreover, in some cases, the problem was found to be more serious in the 1953 car of a particular make than in the 1952 model.

In these studies preignition and wild ping were identified by a technique that makes use of the spark plug as an ionization gap.