fuel cap vents

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scubarider2
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ok

Post by scubarider2 »

OK, just pulled my vent caps and I DID DRILL ALL THE WAY THROUGH AND JUST EPOXIED THE TOP SO THE TUBE WOULD SLIDE WHEN OPENED AND CLOSED.
Dennis
Dave Krall CFII SEL SES
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Post by Dave Krall CFII SEL SES »

So what's the final verdict on vents? Just top only, or all the way through?
Anybody have some that are working well with just drilling through the top?
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stede52
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Post by stede52 »

you definitely need to drill all the way thru.  I drilled one hole thru the top to fit the vent tubing and two smaller 1/8' holes thru the bottom.  I also didn't want the holes in line with each other to prevent more of a possiblity of the fuel splashing up thru bottom hole and out the vent tube.

Steve
Roger
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Fuel caps

Post by Roger »

Like some of the others, I also drilled a 1/4" hole through both sides of the fuel caps, then I talked to Troy's dad who works at Just, and he said to drill a 1/4" hole in the top, and a 1/8" hole in the bottom. I used the Hysol epoxy to heal up the bottom side then drilled the 1/8" hole through that. Haven't used it yet, as I'm still working on the engine and instrument panel.
Roger
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CanadianSheepHunter
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Re:

Post by CanadianSheepHunter »

What are the advantages of pressurizing the wing tanks with the wing tank caps with forward candy canes?
Uwe Jens wrote:Hi Paul and Dennis
We don´t need to forget that these venting tubes are not only for ventilation but also for pressurized the fuel tanks while flying.  THis is why I still don´t understand how the drill caps works.
Paul, I believe you could place the venting tubes on the closer side of the tank to the cockpit, so when you fold the wings they stay on the higher place and won´t have a fuel leakeage,  if you fix the tubes on the tank you will have a problem, since you´ll change the tubes direction.  They will end up perpendicular with the air flow producing a ventury and it will suck the fuel from the tanks to the outside.
I have an idea, I am giving you some numbers on pieces of Spruce since I am not sure on how to explain this in English.  
You could place AN816 NIPPLE on the tank, size 1/4 Steel 4-4; then you put a NUT sleeve Coupling in the tubes, this way you can release the nut and turn the tubes to the other side when you fold the wings, this will always make the tubes will be right with the airflow; or just place a plug in the tubes when you fold the wings.
I hope you get the idea,  I think the people who already placed the tubes in the caps also will need to rotate the caps when they fold the wings to prevent the ventury suction.
Regards, Uwe/.
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stede52
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Re: fuel cap vents

Post by stede52 »

I don't believe pressurization was the reason for the design of the old highlander fuel caps :? , if it was they would have continued the design for the new tanks. So the answer is, no advantage. As you know the primary purpose of any vented fuel cap in a gravity feed system is to eliminate the possibility of a vacuum which will stop fuel flow to the engine. So it doesn't matter if is like the older highlander inverted 'L' style cap or candy cane style its just a vent. :)
Steve D N419LD
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BDA
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Re: fuel cap vents

Post by BDA »

After drilling the vent holes out a little, my tanks levels are staying fairly even now.

As for presurising the tanks with tube vent - that is a way to add a little fuel presure without using a fuel pump.

Many of the older cubs had no fuel pump.
SuperStol XL Alaskan With Titan 340
N331AK. Shawn Taplin
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