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Need some advice about clunk line.

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Need some advice about clunk line.

Old 05-20-2003, 03:02 AM
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lownslo
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Default Need some advice about clunk line.

I am going to put a larger tank in my 4*120. I have a Saito 150 in it and it really eats the fuel. I noticed after a rough landing that my clunk line was "doubled up" and stuck at the front of the tank. (this was in my 16 oz. tank). My clunk is nice and free at the rear of the tank.
I want to put in a 20 oz. tank... and wonder how you can keep that line from doubling up and sticking to the front? I am thinking... to run the brass tube back pretty far in the tank before installing the pick up tubing and clunk. What about a dive if the fuel is low in the tank?? Will the clunk need to come forward??? .. thanks... lownslo..

Bob
Old 05-20-2003, 03:22 AM
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C_Watkins
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Default Need some advice about clunk line.

The clunk should never... ever come forward. In a dive, you generally aren't
at full throttle anyhow, and there is enough fuel in the line to take you all the
way to terra firma, or terminal velocity, whichever comes first for your plane
I could see, on a very extended dowline, where you might get a burble from an
air bubble, but it should be just a momentary event, at best.

I've seen long clunks before... or maybe they were homemade.
Simple as soldering a bit of brass tubing to a clunk, if you are comfortable soldering.
If not, simply do the tank cap as normal, and exit it with a short piece of fuel line,
then a length of brass tubing, then another section of fuel line to the clunk.
I don't really like that method, but have seen it used plenty of times.
To me, it's just an additional two connections that could, some day, cause trouble.
Old 05-20-2003, 01:38 PM
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lownslo
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Default Need some advice about clunk line.

Thanks...... I was thinking about something like that, but needed to know if some other people have done something like that...lownslo..

Bob
Old 06-10-2003, 10:34 AM
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sillygoose2003
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Default Need some advice about clunk line.

I have put a short brass tube in the fuel line inside the tank itself to stop this from happening in the past and have had no problems with this method
Old 07-18-2003, 05:05 AM
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f4ucorsair
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Default Need some advice about clunk line.

( In a dive, you generally aren't
at full throttle anyhow, and there is enough fuel in the line to take you all the
way to terra firma, or terminal velocity, whichever comes first for your plane
I could see, on a very extended dowline, where you might get a burble from an
air bubble, but it should be just a momentary event, at best. )


Well Itend to do full throttle dives and I have reached terminal velocity. It's not good, fuel the fuel falls tothe front of the tank and I get nothing but air in the line. Haven't figured out a solution for this yet, but I'm still looking. If you or anyone else has some ideas, let me know.
Old 08-11-2003, 05:50 PM
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bighawg
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Default Need some advice about clunk line.

A good fix is to put a pc of plastic(hard ) tubing in-line inside the tank. It acts as a stiffiner and will not let the fuel line flex forward on ya. A pc of plastic push rod works well. If you are like me, you have some pcs lying around the workshop, leftover pcs you cut off.
Old 08-12-2003, 01:52 AM
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downunder-RCU
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Default Need some advice about clunk line.

One way to ensure the clunk is never out of the fuel even in an extended dive is to use a bubble tank similar to what Jett sells. Basically the tank is a bladder fitted inside a normal fuel tank. Suck all the air out first then fill with fuel. If you use a sintered bronze clunk filter then there's no hole to get covered by the bladder as it shrinks during flight. Muffler pressure gets fed into the normal tank but acts on the outside of the bladder.

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