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RV3 header tank vent details

BruceMe

Well Known Member
I recently purchased an older RV-3 with header tanks. There was some trouble with the vent, which appears to be non-standard. I was wondering if anyone could describe or take a picture of the vent system for the header tank.

They installed a pitot-like ram air vent. I think the issue is that it can't actually drain properly with full tanks and high climb angles, so if the tank is full, it overboard into that tube and causes a partial vacuum. There are no pumps and the vent tube is at the same height as (maybe even below) the carb and causes a back-siphon effect.

https://photos.app.goo.gl/dXaa8q2C2FpJNfRu9

The solution the previous owner did was to put a hole in the cap, which is prone to water fouling [fowling], I wanted to know how the header tank should be vented to work properly without a fuel pump.

Thanks,
-Bruce
 
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RV-3 fuel vent

Bruce,

I will need to look at mine when I get home this evening.

As I recall on my restoration there is a vent fitting at the top front of the tank.
And a 90 degree fitting turns down with a length of tube that extends down through the bottom skin.

I will let you know.

Jon
 
Vent

I just got access to the online plans, It's described in the manual section 8 page 9 and DWG 32 is the fuse fuel tank. It shows a vent which is just AN elbow fitting at the front of the tank. There's no tubing attached, it vents to the cabin in so far as I can tell. Let me know if you see otherwise?
 
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fuel vent

I am not real keen on having an open fuel vent into the cabin. Overboard would be best.

I will let you know what I have on mine because the upper skin is not attached and the tank is loose.

Jon
 
Does the tank vent collect ducks or geese? If it collects one of the endangered species, you'd need to contact a suitable wildlife expert.

Here's the tank drawing from the plans. You can get a full size copy from Van's for a nominal fee.

Dave

Screen Shot 2022-08-22 at 12.21.15 PM.jpg
 
Vent

Ours runs straight down and out the belly as others have described. It vents fuel overboard with the tail up when totally full of fuel. I only fill it to about an inch below the top and none is lost.
 
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