Less- - - -a lot less. "Ping" is detonation, which deflects piston ring lands, breaks piston rings, and burns holes in pistons. Gasoline engine detonation is the most destructive non-nuclear power known to man. Just a few seconds of detonation during a dynamometer run I was doing on a MOPAR 440 at 6500 RPM and 714 HP burned a hole in the top of a piston over an inch in diameter. A very lean fuel/air mixture will detonate regardless of where the ignition timing is set. Try using a little choke to richen the mixture when the engine starts to detonate and see if the noise reduces or stops.
Jerry
