Seven months after my wife and I joined the 2017 California Caravan to drive with two other Airflows from San Diego to the 54th National Airflow Club meet in St. Paul, Minnesota, our 1937 C-17 Airflow sedan developed a knocking noise that sounded much like a failed rod bearing. You might have seen photos of Steve Wilson and I pulling the engine on this web site or on Facebook. It's now been overhauled and reinstalled by Phil Putnam, and this morning I took it to the Dyno Shop in Santee California for a tuneup. Click the image for more details on the results. This same shop had tuned the car before our long trip, so they were able to compare performance before and after the rebuild. The car ran very well before the rebuild, and had the engine problem not developed, we wouldn't have taken it apart. But it runs even better now, with almost 10% more horsepower and 15% more torque. Air-fuel mixture is around 11.5 at speed, which I'm told is a safe setting for an older engine, though not the most economical.
Here's a short video of the process.