Tank height technicalities.

What is the determining factor in setting the tank height for upright or inverted engines? Some will say spray bar, some will say the center of pumping action (the area where all of this air intake suction starts), and I have read in this bulletin board the center of the needle valve (with respect to the LA 40/46 as used with the new plastic tank as supplied by Top Flite).
I vote for the center of pumping action.

>What is the determining factor in setting the tank height
>for upright or inverted engines? Some will say spray bar,
>some will say the center of pumping action (the area where
>all of this air intake suction starts), and I have read in
>this bulletin board the center of the needle valve (with
>respect to the LA 40/46 as used with the new plastic tank as
>supplied by Top Flite).
>I vote for the center of pumping action.

If you stick a filled hose in a gas tank (or water barrel) you need to loop it over the edge and bring the end down below the top of the liquid in the container for it to flow out the other end. Lower the end even further and the liquid will flow faster. Raise the end above the top of the liquid in the container and it will cease to flow. The needle valve is the end of that hose. I vote for the needle valve, realizing that there are circumstances where you need to raise or lower the tank slightly.

On the other hand, we have a Fox 35 that has the piston for a Fox 36 in it. The case, sleeve, and all the rest of the engine (except for the head) remain unchanged. We had to change the height of the tank a full 1/8 inch on the same plane when using that engine. I have no explanation.

I recall having to adjust the tank height on the Humongus/.46LA when I changed mufflers...from the Mac's tuned muffler to a Big Art Tube muffler. Also had to change tank height on the (late) Lancer when changing from Scott's ST .60bb/Mac's Muffler to my own 2Star .60bb, which is a copy of the ST. Hmmmmm. Steve

>What is the determining factor in setting the tank height
>for upright or inverted engines? Some will say spray bar,
>some will say the center of pumping action (the area where
>all of this air intake suction starts), and I have read in
>this bulletin board the center of the needle valve (with
>respect to the LA 40/46 as used with the new plastic tank as
>supplied by Top Flite).
>I vote for the center of pumping action.

I don't know about that - it's something beyond merely what the pressure at the spraybar, but what is really is seems to be a complete mystery.

The right position is the position that makes it run the same upright and inverted. If that position is different between maneuvers and level flight, that's a problem with the engine, not the tank position.

What effect does the position of the remote needle valve on the LA series have on tank hight. Do you need a radically different position because of the unconventional location of the needle valve.

>What effect does the position of the remote needle valve on
>the LA series have on tank hight. Do you need a radically
>different position because of the unconventional location of
>the needle valve.

That should not affect it any more than if you simply looped the fuel line from the tank to the engine. It doesn't affect thne position of the tank.