Quote: Make sure you have no leaks UPSTREAM of the sensor. Any header tubes that might be leaking or flange gasket leaks will suck in air and give you a lean reading.
I don't recall your cam specs but if it has a lot of overlap, exhaust reversion will cause random misfires (that choppy idle sound)and the O2 sensor will read lean even if it is actually rich. Misfire = no oxygen was used so it get pumped out past the sensor which does its job and reads it.
Get the engine to sound happy first and then use the readings to tell you what changes to make. They will not likely be where you expect when you are done at least as far as idle and cruise go.
Kevin
Good points, Kevin. There are no detectable exhaust leaks. Cam overlap? Oh yeah! Plenty of it. I didn't consider that.
I am curious as to what jets other guys are running in similar engines. When I switched from #86 to #88 primary jets, My IN GEAR idling readings fattened up from over 17 to around 15.8 to 16.0+ so I wonder if it will improve further with #89 or #90 jets. That seems pretty huge though.
