What is knock?

[spooldup]

I hear everyone talking about this and saying it's not good. Why? What is it?

 

[jwaller]

perignition....in the very worst case senario you can hear it like popcorn going off inside the motor

 

[syntax]

what knock is(also reffered to as detonation) is when the the air fuel ratio ignites without a spark from the dist. basically, due to the volitial nature of a combustion chamber, hot spots can appear on the cylinder wall and when air and fuel enter the chamber sometimes it will just ignite there on the spiot because of the conditions of the cylidner, as you can imagine is can be very deadly to your motor to have yuor air/fuel mixture to ignite when your piston is on its way up to compress the air