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04-26-2024, 01:21 PM | #21 | |
Senior Member
Join Date: May 2010
Location: Clinton,WA/Whidbey Island
Posts: 4,119
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Re: Carburetor leaking
Quote:
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04-30-2024, 04:10 PM | #22 |
Junior Member
Join Date: Apr 2024
Posts: 3
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Re: Carburetor leaking
I had a leaky carb make me nuts for weeks when i first got my A400. About half the time I'd walk away from the car I'd come back to a huge fuel puddle underneath. I installed a new Viton needle/seat but could not get it to seal reliably. I built the rig shown in the photo to be sure the float height was perfectly adjusted and to study what was going on. Look at the float photo and see there is a slight dimple worn between the two holes. Now look at the photo of the new Viton needle. In the photo (and when looking at it) the machining makes it hard to tell if the brass of the needle tip is rounded or has a slight point but it actually is slightly pointy. Turns out all of this matters. The float does not go perfectly up and down in the bowl; it pivots. This means there is a very slight side load on the needle. If the needle doesn't ride smoothly across the top of the float the side loading can be enough to push the needle against the side if the seat and hang up. The pointy needle was occasionally catching in the dimple and then being cocked inside the seat. I sanded and then polished the float with a Dremel to remove as much of the dimple as I dared (the photo is actually the "after". The dimple was originally deeper.) I then sanded away the point on the needle and polished it nice and round. Finally, problem solved. Been leak free for 18mo/2000mi of driving.
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