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Header Tank Installation

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Aaron Dwyer

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May 16, 1999, 3:00:00 AM5/16/99
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Hi all, I want to install a header tank. My goals are more
consistent engine run and larger fuel supply for a safety net. Is there
anything I should consider when doing it? I bought a Sullivan 2 ouncer
Flex-Tank. I plan to mount it on the left side of the heli, opposite
the pipe. Should I try to make it level with the carb, level with the
main tank, or what? How should I affix it? Any help is appreciated,

Aaron


Aaron Dwyer

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May 16, 1999, 3:00:00 AM5/16/99
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Trip, thanks alot for the reply. I think zipties will be ideal in my situation
also, as long as I can keep from deforming the tank when I tighten them. I will
also pad the tank so it doesn't turn into a foam factory.

Aaron


TripRGitar

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May 17, 1999, 3:00:00 AM5/17/99
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I have the one mounted on my shuttle about level with the carb, didn't really
plan it that way, just took advantage of the best place to mount it. I used
those nylon pull ties to fasten it. I also still use a filter from the header
tank to the engine, but elimited the one from the main tank to the header. You
should also consider using a filter on your muffler line into your tank. Often,
the back pressure can send dirt into your tank this way. Use good metal
filters, not the blue plastic crap.....Well, I spoke my peice on this. The next
guys turn....Later...Jim.
aka.........Trip

TripRGitar

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May 17, 1999, 3:00:00 AM5/17/99
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If your tank turns into a foam factory, you might want to check for vibrations.
I have no problem and the thickness of the tank, you won't have to worry about
it collapsing it. Just make sure you have a good sturdy tank..Later. Jim...Trip

kelly_...@mail.northgrum.com

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May 18, 1999, 3:00:00 AM5/18/99
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Aaron:

Try to keep the center of your header tank AT or slightly above the
needle-- This will ensure that you always have postive head pressure on
the needle and the tendency will be to run slightly rich; by mounting
the tank slightly higher than the needle you will have a gravity-feed
system instead of the dreaded venturi suck.

Kelly

In article <373FA833...@calpoly.edu>,


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Steven655

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May 18, 1999, 3:00:00 AM5/18/99
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Okay not to stick my foot in your mouth. What happens when you go inverted? The
tank is lower then the carb.
Steve

Aaron Dwyer

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May 18, 1999, 3:00:00 AM5/18/99
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Kelly, sounds reasonable, but doesn't the main tank still force the
engine to suck, because it's mounted down low, and the header tank has to
tug on it to get fuel? As fuel is sucked out of the header tank, fuel has
to be replaced in it also, and this requires pulling it up from the main
tank...right? Seems like the in and out flow in the header tank would
nullify the effect of where the header tank is mounted, and it wouldn't
matter where it was mounted. Or maybe the average of the two tank
locations, accounting for differences in size (header tank has less
influence because it's smaller), would determine the actual effect. Just
pure speculation,

Aaron


Ergo_Bill

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May 19, 1999, 3:00:00 AM5/19/99
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I may be totally off base, but as far as the carb sucking fuel
I thought that was why the fuel system was pressurized.
I installed my header tank so the fuel out line is level with
the inlet on the carb, Have not gone inverted yet but engine
rpms are quite consistant.

--
Ergo_Bill

MArmitstead

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May 19, 1999, 3:00:00 AM5/19/99
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The fuel feed pressure that the carb "see's" is a combination of exhaust
tapping pressure + the head or weight of fuel which is governed by it's
relative height to the centreline of the carb main needle.

Having a small header tank ( 2oz) or so right on the centreline of
the carburettor will only be at the optimum height when the main (larger
tank is empty.

If the main tank is higher or lower than the centreline of the carb
needle (heli's are usually lower) then this creates a setup where the
mixture leans off as the main tank empties and richens up when the heli
is inverted.

Some engines are very sensitive to relative tank height and exhaust
pressure ,some are not.

Aside from the head of fuel and exhaust pressure issue,there is also
another factor which is the carbs own ability to draw fuel,this is
largely governed by the relative bore of the carburettor for the engine
displacement and the amount of engine compression.Large bore
carburettors are more sensitive to tank height and more prone to fuel
draw problems than small bore carbs are.

IMO header tanks are only useful as a means of always keeping a "still"
tankful
of fuel ,even when the main tank may be foaming (boiling) like hell,
when it's nearly empty.So it increases the reliable run time and avoids
lean runs by always picking up unbubbled fuel,hopefully.


Martin

Steven655

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May 19, 1999, 3:00:00 AM5/19/99
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Mister Bell would be proud of your writing skills. Maybe you can wright for a
magazine.!!!
,Still confused header tank man

Mfelder

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May 20, 1999, 3:00:00 AM5/20/99
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Make your life simple man, just mount the header tank at the same line
as the carb fuel inlet. I did with four of my helis and I have never had a
fuel problem. Make sure you put a filter on the pressure line coming from
the muffler. My experienced two cents.

Steven655 <stev...@aol.com> wrote in message
news:19990519190443...@ng153.aol.com...

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