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I think that -- as long as there isn't any bubbles in the line -- the fact that the needle valve is remote is going to change anything.  There's a certain amount of head drop (or gain) because of the height difference from the liquid level (or uniflow vent) in the tank to the opening in the spray bar, and there's a certain amount of head drop because of the rate of fuel flow and the size of the orifice in the needle valve.  Where you put the needle -- whether it's going through the spray bar or at the end of the pick up tube -- shouldn't matter.

There's a lot of other reasons why a remote needle valve may give you grief (particularly anything involving bubbles in the fuel), but not, I think, that.

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Have you tried the spigot like Brett suggested?


Martin

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If I read this correctly the engine is canted down by 10º and it goes rich only during outside maneuvers, yes?

That 'should' cause any ballistic based effect within the engine to give a certain leanness as the fuel/air mix travels down that 10º slope back to the lower crankcase.

There is no doubt in my mind that the fuel/air mix does indeed coalesce on any surface that it comes in contact with and will pool in any available crevice despite the tornado of closely moving parts that are in close proximity.

I read with interest about a MVVS 49 converted to a diesel for stunt use - this was side mounted and burped badly on the outside maneuvers.
The cause was oil collecting in the fourth unused port cutaway in the lower crankcase, that came loose only on outside G forces.
That vestige of a port was plugged up and the problem dissolved. But everything else about that engine was around 90º compass points and different from what is presented here.

But there is a theory I read about in combat models that proposed that the column of fuel and air trapped between the spray bar and the spinning crank shaft is also subject to G forces and will act as a throttle of sorts. This constantly moving forward (by force of inertia) column only has the way forward open to less than half of the time (140º?) and the remaining degrees is slammed up against a closed port, pooling there until a window of opportunity opens for it to flow forward again.

Here, the intake is sloped by 10º towards the centre line of the crank and will act as a richening device, releasing its 'column' all the more readily during the outsides.

I humbly suggest placing that 'column' of fuel and air or the intake parallel to wing so that there is no force feeding going on and see how that goes.

Good luck mate.

P.S. What I am trying to say in not so many words is that you have a 10º down draught carby for the outsides and a 10º updraught for the insides giving a total of 20º difference depending on the direction of maneuver.

Hi Steve,
             I am thinking all that is needed is a non biased or 0º intake tube and leave the engine mounts at -10º.
By the way, lengthening the intake will only make the draught angle more effective and the problem worse.

Surely its easier to machine a new back plate for a 0º intake than to completely re- engineer the nacelle.
(Have you seen the work that Laurie has put into it here? I would exhaust every other possibility first.)

Laurie,
          have a talk to the combat guys who have has experience with slightly canted engine bearers that allow their exhaust to clear the wing.

Some of those may have had similar effects to what you are describing.

But anyway, it would be interesting to here from you when its all figured out.

Good luck mate.

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