Bill DCat

Hello all,
I'm in the process of mounting a 14oz Great Planes fuel tank in a TopFlite 1/7scale Mustang. I have a SuperTigre G75 inverted engine mounted to the firewall. At it's lowest mounting position (the wing mounting plate won't let it get any lower) the fuel tank is still about 3/4" above the centerline of the carb. I've read where it's really critical on inverted engines to have the tank mounted in the correct position.

My question is this, should I be worried about the 3/4" abover the carb centerline, or should I be OK. Does anybody else have similar setup, and what did you do?

I love this forum for throwing ideas around and picking up new tips & tricks.
Thanks in advance....

MILDBILL-RCU

My Feedback: (6)

Howdy Bill, I built that with a super tiger .90 & mounted it sideways for that very reason. When tank is full & engine not running, fuel will be drawn to the lower spot (carb) by gravity & drip out the carb. while running, your needle valve will have to be adjusted for the fuel that has gravity helping it go to the carb, with or without muffler presure. (the setting will be leaner if you run muffler pressure, & richer if you dont). Once the level in the tank gets close to the same as the carb, the engines vacuum will be drawing the fuel from the tank, not holding it back, as it was when the tank was fuller. this is the leaning out tendence that these have when inverting the engine's. Try a smaller tank. or, a remote needle valve, mounted at the very top inside edge of the firewall. An extension on the end pointed down should help hide it and the gravity issue with the fuel is weak'nd,(not totaly eliminated). The fuel now will not have the same gravity pulling it out of the tank, due to the restriction of the remote needle valve. This should help it run more consistantly through a tank of fuel. Hope this help's & good luck. MILD BILL

Ernest-T

My Feedback: (7)

Another option is to put in a Perry pump to regulate the fuel flow. I used one on my inverted 4-stroke in the TF P-51, and I think the same pump will work with 2-stroke engines.

DBCherry

My Feedback: (4)

Or use a 12 ounce main tank, with a 2 ounce "header" tank mounted in a lower position.

It's quite often possible to locate a small tank in a spot that will be level with the carb.
Dennis-

Bill DCat

Thanks for all the replies. I emailed Top-Flite about this problem and they suggested that I route the fuel line out the firewall, then up above the centerline of the tank, then down to the carb. They said this should stop the potential problem of fuel siphoning into the carb and engine.

I think I'll give this a shot first. If I have any problems I now a few more solutions to try.

Thanks again...

ghendrix01

My Feedback: (1)

Bill DCat,

I have not had any problem with siphoning of fuel on my TF P51 with an inverted ASP 91. I think it is because the plane is a taildragger and that puts the tank lower than the carb while at rest. If the tail is raised to level the wing with the engine fuel lines primed, siphoning will occur. Since this only happens with the engine running during takeoff and flight, the siphoning is not a problem

George