Doc, I'll have a look at this issue when I do the final plumbing. At the moment, the plug for the tank fits a hole in the firewall so that only the ends of carb, vent, and fueling tubes protrude. This is almost directly in back of the carb opening and I'd guess there is about an inch of space there Maybe a bit less. I could enlarge this hole but can't move the tank (without completely rethinking the setup). I think I'll just test it like this. I have been planning some extensive on-the-ground but in-the-model engine testing anyway.

Still lots of little stuff to do.