Robin, It seems that running pressure, with a uniflow tank, or not, is an often confusing issue. You'll recieve almost as many different suggestions as there are people whom you have asked.
Ralphs suggestion falls into the category of being helpful, and making suggestions based on what works for him. I do not intend to be in any way demeaning, but setting a tank up as he suggests totally removes the tank from the category of "Uniflow". The tank will become nothing more than a standard vented tank with pressure supplied to it.
This means that the problem uniflow tanks are designed to limit, the subtle speed up in rpm as the pressure head goes down as the fuel is used, is no longer working for you.
In practise, some do not like to use pressure at all. That's a valid choice when they are willing to accept the results.
I personally always run pressure with the pressure going to the uniflow. As Ralph and others have said, pressure can smooth out the fuel delivery, esp. if your venturii is larger than the engine can effectivly draw. Another reason, and the main one for which I use pressure, is the problem of the rpm regulation when the wind comes up a bit.
Without the system being closed as it is when running pressure, the engine goes slightly rich into the wind, and leans a bit going down wind. Precisly where we would want it to do the opposite,
if we had to have an rpm change in level flight. Using pressure to the uniflow closes the system, and the uniflow run scarcely changes rpm accept where we want it to in a 4-2-4 breaking run. The uniflow does it's job making the fuel head appear to be constant, until the end of the flight when the uniflow uncovers. On many setups, that point in the flight is readily recognizable, and gives us a good indication that we are almost out of fuel.
Best of luck with whatever decision you make, and enjoy the Sport/ hobby.
Topic: UNIFLOW PLUMBING ....With or Without Pressure ? (Read 2382 times)
