What does preignition sound like?

[Tycer]

Hi all. Thanks again for all your help with the coil issue! I am concerned about possibly having too much total timing advance.
There’s a light rattle I need to track down this weekend, but it does not fit my past automotive experience of the sound preignition makes.
My mental recollection of preignition sounds like marbles being shaken in a tin can. This ain’t what I hear.

 

[alldodge]

Preignition only happens at higher rpms, if your hearing it at idle or a bit above I would think exhaust shutters/flappers

 

[Tycer]

Preignition only happens at higher rpms, if your hearing it at idle or a bit above I would think exhaust shutters/flappers

Wide open. And it’s pretty quiet even with the doghouse off. Can’t really hear it over the general engine noise. Could be the alternator rattling or the spark arrestor or... I’ll take the stethoscope out this weekend.

But my question is is pinging in a 140 as sharp and pronounced as in a car?

 

[scoflaw]

It can happen at lower rpm's as well, when the engine is under a load.

 

[alldodge]

But my question is is pinging in a 140 as sharp and pronounced as in a car?

Same noise just may sound different because of open air

 

[Tycer]

It was much less pronounced than my memory. The dizzy mechanical advance stop plate was worn to allow too much advance. Fixed it. Sounds great now.