ALRIGHT!

Now I see why no one replied to my previous post -
Its nothing more than novice-babble and misunderstood semantics on my part.

Did some web research and realized that.

Detonation occurs AFTER ignition as a result of advanced timing raising the chamber pressure to quickly instead of a slower controlled burn initiated later in the engine cycle. I suppose excession compression ratio could cause a similar result.

Pre-ignition on the other hand is a result of chamber combustion before a spark occurs. This could be caused by either a glowing spark plug, residual carbon embers or overheated metal, like a valve within the chamber.

Pre-ignition is more likely to occur closer to BDC because the spark required to ignite the mixture is proportional to the chamber pressure. That is, more spark is required as chamber pressure increases. For some reason I though it would be the other way around.

Pre-ignition causes catastrophic engine failure very quickly whereas detonation can be tolerated for a longer duration.

SO detonation could be remedied as TECH suggested, by either retarding the timing a bit or a ritcher mixture - maybe a little of both. If on the other hand its caused by a high CR, higher octane could be the solution.

OK - Back to the books - Bert