Ford Flathead AFR Gauge Anomalies

[glennpm]

I started this thread on HAMB, https://www.jalopyjournal.com/forum/...alies.1337799/, and got a few replies but nothing since Friday so excuse me for asking here too.

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
- Power valve sizes, don't know yet
- Accelerator pump rod is in the Summer position
- 97 Heaven rebuilt these two carbs years ago for me and have around 2,000 miles or so on them
- Floats set correctly
- Drive at around sea level or so
- Pic of air cleaners used below
- Fuel pressure is ~2.5psi

The reason for installing the AFR AEM gauge was to see where I'm at. Car runs well, required choke to start at all times and I thought I could be running lean.

- At idle ~1K or so, the AFR is about 13.5- 14.whatever
- As soon as I give it ANY gas on the road, APRs are at or slightly above 10
- Plug color looks decent. Pics taken this morning below

Given that the power valves activate at half throttle or so, not sure if these could be a problem.

Artificial intelligence take:
"The Stromberg 97 carburetor typically comes with a Number 65 power valve for sea level use, but the appropriate size can vary depending on the specific application and fuel requirements.
For dual Stromberg 97 carburetors, it is common to use a Number 65 power valve, as seen in some installations where the setup involves multiple carburetors."

From Uncle Max, re. dual 97s:
https://www.jalopyjournal.com/forum/...t-jets.419923/
"I don't believe in adjustable jets. (where's the baseline?)
I do believe in marrying the right jets with the right powervalves, remembering that a properly functioning powervalve starts to enrich the mixture at about 1/2 throttle - due to the "hydraulic" action of the accelerator pump, and becomes fully open at the end of the stroke. I also believe, for your flathead, assuming your're not planning to do much driving in the Andes or Himilayas, the best choice is .043 mains & number 69 powervalves. Set it and forget it.
No Strombergs were killed or injured during this post. . ." :-)