Greetings all,
I noticed a few postings regarding O2 sensors hooked to air/fuel ratio
gauges. I installed one of these setups in my Spit about 2 years ago in an
effort to sort out my 40 DCOEs. I got the gauge from JC Whitney (they no
longer carry them) for about $30. It's a 10 LED display, packaged in a
standard 2-1/16" round gauge housing. The LEDs read from 17.1 to12.1 A/F
ratio. The gauge is made by Cyberdyne of New Eagle, PA (412-258-8440). Two
years ago the gauge sold for about $50 directly from them.
I hooked the gauge up to a standard, generic one wire O2 sensor that I got
from a local discount parts house for about $22. The toughest part of the
installation is getting the sensor into the exhaust system. It needs to be
mounted in the exhaust stream as close to where all the gases come together,
i.e. just behind the collector on headers, or at the base of the cast iron
manifold. You'll need to come up with a set of threads that are 18mm x 1.5mm
(standard thread for 02 sensors)--weld and tap extra metal onto the exhaust
pipe? I welded a volcano shaped mound just behind the collector, then drilled
a hole(21/32' or 5/8") into the extra thickness.
Electrically, these circuits run between 0 and 1 volt DC. Once the sensor
hits operating temperature (about 600 degrees) the voltage fluctuates very
rapidly. You'd need a very good digital meter and a quick eye to get a meter
reading. At the stoichiometric ideal (around 14.7) the sensor produces about
0.5 volts. At steady cruising speeds it could be done. The lower the voltage
reading, the richer it's running. Around 0.98 volts your A/F is about 17 to
1.
I still rely on my gauge to keep my Webers running well--mainly the idle
circuit as the air temps change.
Hope that helps,
Charlie B.
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