So….more header talk….this had me scratching my head

Mattax said
Bruce knew and wrote plenty about reversion so I have to disagree with that. In fact I recall discussions with him about black up the intake and even into the carbs.

I agree that when statements are taken out of their original context, they may in part no longer be true.
When a carb is delivering a flat AFR in the power band, increases or reductions the velocity through the booster still produces the same AFR.
Of course the first part is critical for the rest to follow.
Click to expand...

LOL remember this:

"Often variations in WB readout of AFR are not the cause of the carby they are the cause of ignition timing alterations, that increases CO etc and causes richer readings. If the carby is dropping atomization quality when the manifold pressure is high then sometimes that can cause CO to climb and cause AFR errors. Remember the carby does the same thing each time you pull the same amount of air down its throat with the same blade positions and the same jets etc so if you fiddle with the base ignition timing just as a simple test and you see AFR changes then you have more idea of whats going on. So have a go and experiment".

The main cause of ignition variation to AFR readout is the energy level of the arc. Low energy doesnt start the flame kernel hard enough and you get an incorrect pressure at TDC. Its the mass fraction burnt that matters at TDC. If it produces peak pressure at say 12 ATDC then thats fine but thats only the peak, its not the mass fraction measurement. No point looking at peak pressure points if its not the correct mass burnt. The more mass that has tobe burnt while the piston is descending the colder is the temperature and cold produces CO. Its matters not what the available Oxygen level is if its not hot enough you only get CO. A cold burn thats stoich or leaner than stoich will make lots of CO. I see it all the time on hotrods, massive CO with lots of O2 left over and heaps of HC and sooted up plugs and its because there too lean .


All the way back in 2011.........:lol: