Here's your basic beginner question from an old C/L flier:

I'm building a Sig SE. I got the Dubro 8oz tank as instructed (it fits really nicely). I assembled the brass tubes, stopper, clunk, etc. It becomes immediately obvious that the clunk doesn't move around very much - ESPECIALLY problematic is the fact that when the tank is in a nose-down attitude, the short piece of tubing is too stiff (or the clunk isn't heavy enough) to bring the clunk down anywhere close to the front of the tank.

When I remove the stopper assembly and hold it vertical (clunk up) and the clunk barely tilts to one side. This is with a really short length of brass tube protruding on the inside of the stopper, so the tubing is as long as practical without touching the rear of the tank. Even when it tilts as shown in the photo, it will hit the side of the tank and stop. Shortening the tube to enable it to slip past the side of the tank will only make it bend less.

It looks like any lengthy vertical dive on less than 3/4 tank will kill the engine. Shorter durations in this attitude would at least cause large air bubbles to enter the fuel line.

What's the solution to this problem?

1) Thin walled fuel line?
2) Heavier clunk?

Thanks!

-brad