Dale;
First, a belated congradulations on your successful 'off field' landing. I've had 2 such encounters (in experimental aircraft) and there's no way to adequately describe the feelings/thoughts running through your head when this occurs.
As for the cause of your power loss, I have for some time been very interested in the NTSB findings of 'power loss for undetermined reasons' in the large Continentals. If you scour the NTSB reports you may be surprised how many times the feds cannnot figure out why the engine stopped.
I think the fuel delivery system on some low wing aircraft with big Continentals can allow the engine driven fuel pump to cavitate when enough air is ingested upstream. I have read that the mech fuel pump is designed to purge itself of smaller quantities of air bubbles, but when they reach a critical mass (i.e., hot conditions, high fuel flow, or a small air leak upstream via the fuel selector valve) the pump can cavitate with instant power loss resulting.
My own experience on this can be found on CSOB. Basically, my F33A was down for about 6 months for a new engine. By the time I got ready to fly again, the small O-ring in the fuel selector valve stem had dried out/shrunk enough to allow air to enter the fuel selector valve. One of my employeed is a very sharp master mechanic & insisted we pull a slight vacuum on the fuel supply line where it attaches to the engine driven fuel pump. After attaching a clear fuel line to the a/c fuel line (so we could SEE any bubbles coming thru), then applying slight vacuum (small hand held vacuum device), I was very surprised to see lots of air being pulled up from the fuel tanks.
It doesn't take much of a 'gap' to allow air to flow into your fuel system. Also, since our fuel tanks are lower than the engine, there will be SOME vacuum occuring there (unlike Cessna's, for instance, which have a slight positive pressure from their high wing tanks). Also, there will be a bit MORE vacuum occuring when in a nose high attitude, as your tanks are even lower than normal, relative to the engine.
I urge all readers to conduct an "UPSTREAM FUEL SYSTEM INTEGRITY TEST".
You can do it yourself, and you may be shocked at what you find!!!
This should give some food for thought. I have recently renewed everything firewall forward, including renewing, and repositioning, ALL fuel lines. When we looked at the previous positioning and condition of some of these lines, I went a slight shade of grey..My power plant, Continental IO470-N