I've put an old/new Fox profile tank on my new Ringmaster. It was the same tank that was on my old "Yellow Jacket" that I re-kitted at the Ringmaster Roundup last spring. It appears to be in good shape, no leaks or dents, etc. When I cranked up my Greenhead .29 it ran just fine. As long as I'm flying level, (upright or inverted) or pulling +G's everything is ok, but when I tried to go outside (-G's) the engine dies.

I raised the tank up about 1/4" above the venturi and flew my RM again this week-end It still ran GREAT in level flight upright or inverted. Still does good when I pull + Gs but conked out when went outside. In fact I had a rather abrupt arrival after trying to come out of inverted flight with a reverse wing over. I've patched up the plane, but I'm bumfuzzled about why it's doing this. I think I'm going to try a "clunk" tank and see if it makes any difference.

Here's a picture of the tank on my old Ringmaster

Could there be something about the engine, fuel line, or anything else that might be making it die when it pulls -Gs?

 HEEELLLPPP!

Had what may be a brainstorm. Here's a picture of how the tank was originally mounted before I raised it about 1/4 inch. If you look at the picture, you'll see that the feed line comes out of the bottom of the ridge that runs along the tank, but the fuel line has to S-turn to get to the inlet on the top of this old Torp. Could the centrifugal force from the outside loop be keeping the fuel from traveling what would then be "up" the feed line into the fuel tubing???

It appears that the front of the tank is crunched. Might be a good idea to pressure check it?

Mine did that this weekend it was a pinhole in the fuel line that opened up during an outside manuever.

Raising and lowering the tank is done to use the G-loads from the turns that affect the fuel feed.  An outside loop exerts load from Gs toward the top of the airplane, making fuel harder to draw.  Makes sense to me that a higher tank would go leaner in outsides.

I'm sure K&B had some reason for putting the exhaust on the left side of the engine, but I don't know what it was.

Many older engines had the exhaust on the 'wrong' side of the engine.  Of course back then it wasn't uncommon for people to fly the other direction (clockwise).  When a profile is oriented for clockwise flight, with the engine mounted on the outboard side of the fuselage, the wrong exhaust suddenly points the right direction.  

Raising and lowering the tank is done to use the G-loads from the turns that affect the fuel feed.  An outside loop exerts load from Gs toward the top of the airplane, making fuel harder to draw.

  Sorry. This is a new one on me.

Raising and lowering the tank is done to get a consistent engine run and lap time either inverted or upright. When the tank is on the centerline of the venturi, some engines will run too rich while inverted. That is why we have to raise the tank on most profiles to balance the run.

The accelleration/decelleration (G-load) through the turns may cause unporting when the tank is almost empty, but it's not a reason to raise or lower the tank. If you experience this problem, you should shim the aft end of the tank away from the fuselage. This extra angle helps keep the remaining fuel in place, especially during the cloverleaf. 

My .02 - gained via costly experience. 

Ron

I think the clunk tank will cure it.  You may also try a standard rectangle type tank on suction.  If you can find one, a chicken hopper type tank is also worth a try.  (Don't ask me why they are called that) .  I have never had any luck at all with the style of tank you show mounted and think that may very well be the problem.  Good Luck

The problem with a clunk is that they require a lot of extra space at the front of the tank for all that plumbing (Hayes brand clunk tanks take less space) and you don't have much room to work with on this plane.

That S bend can't be good for steady fuel delivery.  If you flip the needle assembly over, you will have much more direct feed.  You can adjust the needle valve with a glove and pliers to keep your flesh out of the exhaust blast. 

A chicken hopper might work well, as Pete suggests.  The main tank is shaped much like the tank you're using now.  I have used them with great success.  Brodak carries several sizes, so check their paper or online catalog.  Hoppers are a bit pricey because of all that extra metalwork, so that's a factor if your wife has you on a budget.      For everyone's educational benefit,    the tank gets its name from feeders used on chicken farms, in which a large bin above the feeding trough is filled with chicken feed.  As the chickens dine, the level in the trough goes down, and the bin dispenses just enough additional feed to raise the level back to normal.  I believe there are cat feeding systems, for when the owner goes on vacation (or is just incredibly lazy) that work the same.  However, "cat hopper tank", like "cat house" or "cat fight" might have a slightly different meaning.      Wasn't that interesting? 

Kim

I have been reading this thread, and it doesn't look like anybody has determined if the engine is quitting lean or quitting rich. Sometimes, it's not easy to tell. If it's quitting lean, then there's probably something wrong with the tank. If it's quitting rich, then it might just need height adjustments.  Beyond that, I think the tank needs to be replaced, if not recycled, which would be my choice. Smash it flat, too.  Steve

If it's loading up and quitting rich, then it's possible that a hotter glowplug would fix it.    Steve

Edit: Well, it wouldn't FIX it. I was thinking that it might at least get through an outside without quitting, allowing tank tuning to be fussed with before the airplane is destroyed. How's the new tanks working?