G'day Rich,

The main problem with a tank too high or low is that when you fly inverted it becomes the other way round. In your case you can probably tune the engine fine with the high tank, but when you roll inverted (or push to negative 'G' to be more accurate) you now have a low tank. The engine will now be much leaner. The uniflow tank won't change that at all unfortunately.

The uniflow system prevents the engine getting leaner as fuel is burnt ie the fuel pressure is constant from a full tank to an empty one. But it won't help with a low or high tank situation (actually it can see later in the thread). The system works very well where a throttle isn't used. And can be made to work with a throttle with a bit of extra plumbing (you actually need two check valves).

A high or low tank can also give problems with idle or transition, you set the main needle either richer or leaner than it normally would be to allow for the tank position, but this needle setting might not work well with the idle adjustment. If the tank isn't too high and you set the engine rich you might find that everything works acceptably well though.

If if not you will have to either raise the engine, lower the tank, a bit of both, or look into the fuel pump/regulater systems available.

Good luck,

Dave H