Proper Mixture.

[John Dammeyer]

Hi,

Newbie type question again.

I'm working on improving a 2HP Briggs&Stratten Lawnmower engine.  I have the
electronic ignition complete and when I finish the TDC/BDC sensor disk I'll
try it.  As it is it works with a simulator that produces the pulses that
the sensors would make.  So I can see a nifty advance curve working all the
way up to 3600 RPM.

Next is to improve the fuel delivery.  But How do I know what the optimum
mixture should be at any RPM under load.  Do I purchase an O2 Sensor that
goes in the exhaust?  I have a color tune spark plug and I can use it to set
idle mixture by looking through the quartz window in the sparkplug and
adjusting for blue ignition;  too rich is yellow/orange.  However this
sparkplug would destruct under continuous operation at 3600 RPM.

Tom Cloud mentioned that he had an Oxygen sensor that he monitored under
cruise.  It's no big deal to add a 12 bit A/D to my processor and read the
voltage value.  Question is.... how do I interpret this? 

I can see if there is zero O2 left then I have complete combustion for the
amount of O2 in the intake stroke but if I have a too rich mixture wouldn't
that happen anyway?

Thanks,

John. 
Pioneers are the ones, face down in the mud,
with arrows in their backs.
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