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1973 Chevy Camaro Air/Fuel Gauge - Exhaust Snitch
We Take A Look At FAST's Newest Wideband Tuning Aid.
February, 2010
By Steven Rupp
Photography by Steven Rupp
Properly tuning your engine used to fall more into the witchcraft category than the scientific. It was tough to tell if your ride was running rich, lean, or dead-on. Even if one managed to get it just right at idle, there was no guarantee it wasn't going to be pig-rich at wide-open throttle (WOT), or even worse, dangerously lean. The days of checking plugs and sniffing exhaust fumes are over since the aftermarket has stepped up with easy-to-use, and affordable, air/fuel monitoring systems. The kit from FAST (PN 170634,... The kit from FAST (PN 170634, $208.95 at Summit Racing) comes with everything needed including a 21/16-inch back-lit gauge, Bosch wideband oxygen sensor, stand-alone control unit, weld-in exhaust bung, and electrical connectors. The technology of using a sensor to read the free oxygen level in the exhaust gas and establishing an air/fuel ratio is certainly not new. Back in the early '80s OEMs were already doing it, but the technology was crude by today's standards. It was also geared around emissions more than performance, and had a narrow operation range. It wasn't until later that companies like Bosch and NTK started putting out wideband sensors that were accurate enough for performance tuners. Since then, the technology has progressed and the prices have come down to the point where it can benefit basically any hot rod. The big question is what the best air/fuel ratio is. While 14.7:1 might be best for emissions, the target for performance is around 12.8:1 to 13.3:1, which is roughly 13 parts air to one part fuel. This ratio ensures that there's enough air (the oxidizer) to support the process of combustion. The gauge itself can be mounted... The gauge itself can be mounted just about anywhere. For convenience, we decided to just put it under the dash, so we picked up this mount from Summit Racing. Some gearheads make the assumption that having additional fuel in the mix (rich) will make more power, but it doesn't work that way since you can only burn fuel when you have enough air to support the combustion. This ratio is true regardless of the size of the cylinder. If you want to add more fuel, then you'll need to add more air through the use of a supercharger, turbo, or even nitrous. While running rich will rob power from an engine, it's even worse to run lean since this condition can actually cause engine damage. With this in mind, FAST has introduced an affordable and fairly easy to install wideband air/fuel gauge kit. Unlike some kits that require a laptop, this system was designed to be simple to install and easy to use for the enthusiast who doesn't need, or want to pay for all the bells and whistles. One such person is Mary Pozzi. Mary and her husband David have been trying to nail down the tune on her '73 Camaro but were seesawing back and forth between rich at cruise and rich at idle. With FAST's new kit in hand we wanted to see if a little bit of technology could help the hard-driving duo dial in their Camaro.  About the most complicated...  About the most complicated part of the process is installing the bung in the exhaust system, since it requires welding. If you're not up to it, or don't have a welder, then most any exhaust shop can handle it for a few bucks. Here, David Pozzi used a step bit to get the correct-sized hole in the exhaust pipe. |  The stainless bung supplied...  The stainless bung supplied in the kit was then put in place. It needs to be located either just forward of, or just behind the collector flange. If it's located too far back or forward, the accuracy will be affected. |  Next, David welded the bung...  Next, David welded the bung in place making sure to completely seal the edges. FAST recommends installing the sensor in the 3 o'clock or 9 o'clock position. Also, if the sensor is installed on an open exhaust collector, its readings will be off at idle due to outside air mixing in during the exhaust pulsing. |
 To ease screwing in the Bosch...  To ease screwing in the Bosch sensor, David ran a tap through the bung to clean up the threads. This is especially important if any welding splatter got inside the hole. |  The very tip of the oxygen...  The very tip of the oxygen sensor is delicate and can be easily damaged if dropped or even touched the wrong way, so treat it with care. Before screwing it in place, we applied a little dab of anti-seize to the threads. |  David then tightened the sensor...  David then tightened the sensor in place. It just needs to be snug. If you go overboard, it can damage the sensor. |
 Wiring up the gauge was a...  Wiring up the gauge was a breeze. The 21/16-inch gauge uses a unidirectional plug that's impossible to plug in wrong. Keep in mind, when the engine is running you'll want to make sure power is applied to the O2 sensor processor. This makes sure the sensor's heating element is on, which will reduce buildup of exhaust deposits on the element, thus prolonging its life. |  Rather than bore you with...  Rather than bore you with a blow-by-blow yawn fest on how we wired in the system, we thought we would just show you this schematic. It really doesn't get much more straightforward than this. The entire process, including the welding, took us a couple of hours. |  The back-lit gauge looked...  The back-lit gauge looked great and was very easy to read. We immediately found out that the Camaro was perfect at idle, but after a blast around the block, the gauge showed the Camaro to be running rich at wide-open-throttle, and part throttle cruising. With this information in hand, David could tune the '73s carburetor properly. |
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