Originally Posted by Bill Martins
If you don't put a one way valve in both lines before the tee, you run the risk of backing gas/oil mix or smoke oil into the wrong tank. I haven't done this as I just run a line for each tank to each side/bottom of the plane, on the same side as the filler fitting. That way I can see when the gas/oil tank is full on one side and the smoke oil is full on the other. I like to have a catcher bottle for the smoke oil overflow as that stuff is expensive!
With a lot of aggressive flying I see a lot of fuel in the vent line, I agree with Bill that there is a chance one source could get pulled into another source tank and would personally go with seperate vents.
Since we are talking about tanks
I looked over every gasser set up that was at our FLI event. Naturally these are all Fortitude tanks or Fiji Water bottles. 9 out of 10 were using a 3 line system. Fuel Feed to the Carb, nothing going into this line unless it comes through the filter clunk. Vent at the top front of the bottle that runs to a nipple attached to the front belly of the fuse.<no dangling line hanging out. 3rd line is a fuel dot that is in the front, top corner of the tank and it dangles straight down to the front bottom corner, as the filler and drain point.
I never thought about the fill / drain being where everyone seems to be placing it, but it really works well. They lift the tail of the fuse with their foot as it emptys from the front corner of the bottle. Since many people are running these new filter clunks, they are not causing additional wear and strain on the pickup tube/ clunk filter.