I mostly notice this at about 5500 rpm, in 3rd, coming down from redline or near it. This is with the throttle all the way closed (and the throttle plates look all the way closed with the engine stopped).
This is a twin-plugged modifies 3.2L with PMO carbs & a not too hot cam. The sound is sometimes sharp & loud, and at other times somewhat muffled.
I'm not sure if it is running rich or not - or what else might be causing this problem. Any ideas?
Thx much!