I just finished installing an AEM 30-4110NS wideband UEGO gauge but the AFR readings are off. - 268 CI 59AB block - 4" Merc crank - 0.400 Offenhauser heads - Isky Max 1 cam - Dual Stromberg 97s with .044 jets (stock .045) which operate at close to sea level - Real Bosch 017025 sensor Yesterday I went out and the readings just off idle where reading 13-15 approximately but on the road for 3/4 hour or so, the gauge read mostly at 10 but would bounce a bit up to the 13-15 range, but mostly stuck on 10. My car is not running that rich and has no air leaks before the sensor. The sensor is fairly close to a slip-in pipe ad you can see from my pics I have the same gauge and Bosch sensor on my '40 SBC and the gauge from the '32 tested in the '40 worked fine, i.e. not mostly stuck at "10" AFR. I haven't pulled any plugs yet. Thoughts?
Just trying to wrap my head around the AFR/flathead being used in the same sentence. At any rate, I see the wiring going to the sensor is sheathed/ taped up and wire tied. If I’m not mistaken, and quite regularly are, the wires above the sensor sheath (white) need to be open as one of them actually samples ambient air to make calculations. I think.
The wrap is pretty normal on O2s. The 10 you are seeing is likely right, if the gauge moves higher at idle, then you know its reading. Mine was running that rich but didn't smell to bad, it mostly stunk when I shut it off. I run dual W-1 Carters on a 250 Chevrolet, the gauge is always moving, but on a steady flat 70 mph highway it will read about 15.5 to 16, and 14.7-15.5 at idle. Letting off from 70 mph, the gauge will peg out lean till the rpms come down. I can change the idle ratio 1 point with a 1/16 of a turn of the mixture screws. The Carters use mechanical metering rods, to keep both carbs equal, I made a tool to hold a dial indicator to set the hight of both rods equal. .020" is enough to make a noticeable difference on the gauge. While tuning mine, I soldered two jets closed, then drilled them out till I got the numbers I was looking for. I then replaced them with actual jets of the right size, it kept the cost down and made for quick changes. My SpeedHut standalone gauge goes to zero when the O2s is not reading. Are you reading both sides of the engine?
...I seem to recall something about spacing....a minimum of 10 diameters distance from an ell for placement of the sensor for proper sensing and readings.....but your manufacturers installation instructions should cover that. Sample rate is also something else to consider and affects the reading. Easy to check the plugs for a visual read I ran service techs for years that wouldn't trust their instrumentation...just saying it might be telling the 'truth'
My bbf does the opposite, it goes leaner the more the engine warms up. Maybe the fuel level is rising when it gets up to operational temperature. That would cause it to run a bit richer, but 10:1, my Dominator doesn’t ever get there. Also check for a lean mis-fire.
Good thought but shrink tubing and a zip tie are the way Bosch delivers them. This is a defective one from my '40.
Does that AME gauge have a plug in wire harness on back side of gauge @ gauge ? if so switch gauges between two cars To see if same reading , Then you know Gauge O2 Carb I have several, Autometer comp @ Idle aggressive cam 13-14
Yes AEM says this for the sensor placement, "A weld-in M18 X 1.5 boss is supplied for sensor installation. Mount the O2 sensor in the exhaust system at least 18 inches downstream from the exhaust port. If you anticipate high EGT's (over 800C), run a turbocharger, run at high RPM for extended periods of time or plan on running leaded race fuel then you must mount the sensor at least 36 inches or more downstream of the exhaust port as all of these can cause the sensor to overheat." I have mine at around 22-24" away. I just pulled two plugs noting that I did idle it a bit after my ride so this is not the best read. i I'll do it again properly. That said the plug doesn't look that rich to me. "I ran service techs for years that wouldn't trust their instrumentation...just saying it might be telling the 'truth'" Yup
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