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Fuel tank and carb height - critical or not

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Fuel tank and carb height - critical or not

Old 03-28-2010, 10:20 PM
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shaggy48
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Default Fuel tank and carb height - critical or not

I've heard it said over and over again here on RCU that the carb height should be in line with the midpoint of the fuel tank. And while this makes sense to me for fuel flow especially when the fuel is below half tank. I have a trainer that clearly was not made this way. If I were to try and make the centerline of the tank even with the carb, I'd need to raise the tank about an inch or lower the engine. Neither of which are easy enough to do without major modifications.

Also, the manual for the engine, the 0S 46 LA, says that the top of the tank should be 1/4 to 3/8" above the needle valve (carb). Clearly not in line with the midpoint to the carb rule. So I'm wondering how critical this is? Does it matter on all models and engines? Or is it more critical on some and not on others?


Shaggy




Old 03-28-2010, 10:23 PM
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jester_s1
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Default RE: Fuel tank and carb height - critical or not

The best consistency in fuel pressure comes from the tank being at the centerline of the carb needle, but many engines work fine with it off from that. Go ahead and set the plane up the way it's built and see how the engine runs. If you have trouble, you may need to move the tank but the LA series engines are pretty forgiving.
Old 03-28-2010, 10:36 PM
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DavidAgar
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Default RE: Fuel tank and carb height - critical or not

As mentioned, give it a shot as is and if you have lousy engine runs, then you know what needs to be changed. Good Luck, Dave
Old 03-29-2010, 08:17 AM
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MinnFlyer
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Default RE: Fuel tank and carb height - critical or not

I never pay too much attention to it. After all, when you're going straight up they are not in line.

That whole "The carb must be on the centerline of the tank" thing is one of those "Perfect world" scenarios. Yes, IDEALLY that's where it should be, but it will work just fine in other locations.
Old 03-29-2010, 10:22 AM
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ChuckW
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Default RE: Fuel tank and carb height - critical or not

If it were that critical, half of the ARF's out there would never get into the air. I've seen a couple instances where it made a big difference but that's about it.
Old 03-29-2010, 02:03 PM
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Default RE: Fuel tank and carb height - critical or not

Hi!
It's vital... and half of all trainers ARF's don't get into the air...
Old 03-29-2010, 02:07 PM
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MinnFlyer
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Default RE: Fuel tank and carb height - critical or not

If it's vital, don't ever use your elevator or you will change the relationship between the tank and carb
Old 03-29-2010, 05:31 PM
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rc-sport
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Default RE: Fuel tank and carb height - critical or not

Maybe I have been lucky but I have never had a problem. All my engines are mounted inverted and they all run very well in kits and ARFs

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