Earl, to your #4419, Dec 26, '15 -
Best for the new year, of course...
I think the introduction of the big banjo-back .40 and .45 was earlier than you cited, possibly around 1974 or 1975. It may have been local-area thing. We were in Omaha, Nebraska, not all that far from Fort Smith, Arkansas.
I clearly recall attempting to fly a wart, PB, large case 40 in 1976, while we were at Monterey, CA. The model was SIG Twister or Banshee (basically the same, with small dimensional, and a few cosmetic differences.) That engine stimulated an intense interest in the relationships between a CL model's fuel tank and engine.
In short, that Fox needed a totally non-intuitive positioning of the reference point in the tank. This applied to both profile (head-out sidewinder) and head-up or -down 'upright' installations. Several things I seem to repeat fairly often, here and elsewhere, grew from that interest. The Twister flew very well upright, but flamed or flooded out immediately on sharp outside 'g' or attempts at inverted flight. As I'd been flying the 'modern pattern' since it was introduced, about 20 years earlier, that was unacceptable. The course at the Defense Language School was challenging, demanding time. We devoted family time on opportunities to enjoy the Monterey and Carmel area. Shop was in a large closet in our assigned quarters - and checking out of military quarters is always demanding. At least, that assures we'd have a truly clean and functioning abode for the duration. There many were tools, etc., I hadn't brought with us.
The engine, despite its greater bulk and weight than other .40s, was excellent, aside from that quirk. After an overseas tour, we settled in Arizona, and have been here since 1980. I made an adjustable tank height test stand, adapted for a Tatone mount. It confirmed my thoughts that each engine layout is unique, requires a different "tank height" relationship, and may or may not tolerate slapping it in per received wisdom about spraybar jet and tank reference point, viewed regarding the 'g' conditions in CL flight. It has proven very successful; I like to use unfamiliar engines, which could cause imponderables like the Banjo Fox 40 had.
Long way around, but airs my experience with an early big, banjo-back Fox 40. After "solving" the tank quirk, I used a later Dykes-ring 40 BB-Schneurle Fox in over 500 flights (of about 7 minutes each) in an own-design CL Stunter, which found me 'a few' trophies, BTW.