Aftermarket air/fuel gage - anyone using one (off topic)

[Aribert_Neumann@magna.on.ca]

Thanks to all for the Weber tuning suggestions.

I am considering installing an O2 sensor and an A/F gage to monitor my 40DCOE
carb set up.   Specifically looking at the $35 J C Whitney A/F gage (as opposed
to the $120  K&N unit sold thru Pegasus Racing Supplies).  I am assuming that
the gage is no more that a mili-volt meter.   Anyone have experience with using
A/F gages in general and the J C Whitney A/F unit in specific?

Follow up question - how long will an O2 sensor last when the A/F mixture is too
rich (hours/miles - exhaust tips are sooty)?