Re: Ignition Knock

Posted by Tim Cole On 2022/10/10 18:33:11

Is it pre-ignition or detonation? Pre-ignition occurs when glowing carbon ignites the mixture prior to the spark plug. Detonation is when glowing carbon results in two flame fronts intersecting each other.

When timing is too advanced the knock is caused by the flame front hitting an advancing piston. If there is excessive carbon in the combustion chamber retarding the timing compensates for the advanced flame front caused by the carbon build up.

When the car was new the automotive press pointed out that the 359 with its high compression flathead was subject to carbon buildup.