[Tommy]

Tom -
I recently installed a similar meter in my car with the sensor mounted about three inches from the head on what appeared to be the leanest cylinder. I did a lot of Internet research to make sure I understood the limitations of the sensor before I tried to use the meter to tune the carburetor. The meter seemed to indicate a lean condition (1:15 FAR) at partial throttle cruise, and richer conditions (1:14 FAR) when the power valve opened. My research indicated that this FAR was not a problem at low power, partial throttle settings. However, I found the meter did not react to some jetting changes the way I expected. Wide open throttle (WOT) initially indicated slightly rich (1:14.4 FAR). After I increased the primary jets by 5 sizes and the secondary jets by three sizes, WOT indicated only slightly richer (1:13.8 FAR). I expected a more pronounced change on the meter.

At this point, I don't know whether the meter is inaccurate or my understanding is incomplete. I hope someone who understands these things responds to your question so we'll both know.