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Author Topic: Inverted motor - Needle valve inside or outside circle  (Read 207 times)

Offline Mike Quinn

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Inverted motor - Needle valve inside or outside circle
« on: May 18, 2024, 01:51:32 PM »
Hi

I’ve got an inverted  OS 46 in a Nobler.  Does it make any difference if the Needle is on the outside or inside ot the circle ( as in which way round the spray bar is inserted)?  I’m guessing not as the holes in the  spraybar stay in the same position in the venturi so any pressure differential to the tank will be the same right?

Cheers

mike
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Offline Colin McRae

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Re: Inverted motor - Needle valve inside or outside circle
« Reply #1 on: May 18, 2024, 04:40:20 PM »
I don't think it makes any difference. Just keep the fuel tubing from the tank to the NVA efficiently routed and as short as you can.

I have a 40LA on a Nobler with the NVA inside. Then a 46LA on a Vector with the NVA outside. I don't notice any difference in the engine runs.

And in both instances the NVA's are front type, not the rear needle setup.
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Offline John Skukalek

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Re: Inverted motor - Needle valve inside or outside circle
« Reply #2 on: May 18, 2024, 08:41:36 PM »
When I put the spray bar fuel pick up side on the inside in order to get the needle on the outside away from the muffler on a 46 LA. It gave me problems. I believe that once in the air the fuel flow decreased(causing the engine to go lean) due to resistance caused by centripetal force.
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Offline Ken Culbertson

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Re: Inverted motor - Needle valve inside or outside circle
« Reply #3 on: May 18, 2024, 09:37:22 PM »
I have run it both ways and found no difference.  I do like to keep the fuel line as short as possible which puts it on the outside of the circle for most tanks.

Ken
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Offline Colin McRae

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Re: Inverted motor - Needle valve inside or outside circle
« Reply #4 on: Yesterday at 06:10:05 PM »
Quote from: Colin McRae on May 18, 2024, 04:40:20 PM

I have a 40LA on a Nobler with the NVA inside. Then a 46LA on a Vector with the NVA outside. I don't notice any difference in the engine runs.

One thing I forgot to mention. I run muffler pressure on my LA engines. Not sure if there will be a difference (NVA inside or outside) if only suction or ram air is used on the tank.
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Offline john e. holliday

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Re: Inverted motor - Needle valve inside or outside circle
« Reply #5 on: Yesterday at 07:37:04 PM »
For years and years I have always located the needle where I can get it without interference from the muffler no matter what make or size of engine.  Remeber to build fuel tank accordingly.  Even when I use muffler pressure or uni-flow. D>K
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