mpg on my 340

brasil said

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

Click to expand...

No you probably just need to adjust the vacuum advance can, you can insert a small allen wrench (hex drive SAE, maybe 1/16"?) and turn the screw inside to change how much advance is put in for the vacuum; in your case counter-clockwise will reduce the advance until a higher vacuum is reached. 180 psi is totally in pump-gas territory. Also remember the vacuum advance line needs to be connected to ported vacuum (only works when throttle is open), not manifold vacuum (which is always working including at idle).

Also your A/F at cruise could be a bit leaner, you would pick up some MPG's getting it to 15-15.5:1 but with a TQ in Germany I'm not sure where you'll find replacement metering rods.