mpg on my 340

.... the pinging occurs in two different situations....
When I accelerate FULL ( but not the first lets say 2500 prm ) The AFR is RICH under this condition.. around 10.5 -11.0 ...
The other Pinging ( just a bit......very very silent ) is under steady load.... i.e not accelerating...but also not going slower... also around 2500 rpm ....more or less some revs...
Carbon built up doesn´t exist... and the engine also don´t uses oil.. less than a 1/4 of a quart / 1000 miles
About the camshaft timing... I installed a new chain set
including a chain tensioner...but the Timing issues existed before the chainset change... also...
Engine Temp is 200 °F all the time...I use a 195°F thermostat.... perhaps I need to go down to a 180°F
Thermostat..?? The 340 came from the factory with a 195° F as far as I know...

Greetings Juergen