mpg on my 340

sounds interessting...
my compression is 175 -180 psi on all cylinders.. brakes do not drag... AFR while cruising is around 14.1-14,4
The cam ?? Don´t know... and yes..my Ignition is probably...the weak point...because I can´t use the VC
If I use her... the engine is pinging... The CR is probably way to high ?

Greetings Juergen