Hey Sport,

No problem like I say I wasn't fully understanding your posts.

Ok let's imagine we have a uniflow tank 2" high, mounted with the centre of the tank 1" above the spray bar. the tank is half full. Fuel flows because of the exhaust pressure, the carb pressure (negative), and any head pressure. As you quite correctly say the pressure due to the fuel in the tank is cancelled out because the exhaust is at the same height as the pick up clunk. In this case the head pressure is zero because the floor of the tank is the same height as the spray bar. Now invert the set up. The clunks are now 2" below the spray bar. The difference is 2".

Now let's change the tank to a standard two line set up, but otherwise the same 2" tank mounted 1" high, half full. Now in the upright case the fuel level is 1" above the spray bar so the head pressure is 1". Inverted the fuel level is now 1" below the spray bar, but the tank now acts as a uniflow tank, so the head is 2" below the spray bar. A reduction of fuel head pressure of 3", 1" more than the uniflow tank.

So I still can't understand (now I do) why you would say that a uniflow tank would have less change. If that is what you are saying?

My apologies if I have misunderstood your post again.

Dave H