Return-Path: <13brv3@bellsouth.net> Received: from imf20aec.mail.bellsouth.net ([205.152.59.68] verified) by logan.com (CommuniGate Pro SMTP 4.2.5) with ESMTP id 548287 for flyrotary@lancaironline.net; Sun, 28 Nov 2004 12:38:58 -0500 Received-SPF: pass receiver=logan.com; client-ip=205.152.59.68; envelope-from=13brv3@bellsouth.net Received: from rd ([65.6.194.9]) by imf20aec.mail.bellsouth.net (InterMail vM.5.01.06.11 201-253-122-130-111-20040605) with ESMTP id <20041128173829.FRGX1976.imf20aec.mail.bellsouth.net@rd> for ; Sun, 28 Nov 2004 12:38:29 -0500 From: "Russell Duffy" <13brv3@bellsouth.net> To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Re: Bubbles in fuel line from pump - new valve Date: Sun, 28 Nov 2004 11:38:50 -0600 Message-ID: <000001c4d571$1f7d1b90$6101a8c0@rd> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0001_01C4D53E.D4E2AB90" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6626 Importance: Normal In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 This is a multi-part message in MIME format. ------=_NextPart_000_0001_01C4D53E.D4E2AB90 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable For a moment, let's assume that all your work on the fuel lines has = proven that there's really no leak, or problems. How about the carbs? Is = there a chance you have a needle/seat that's sticking partly open. Is there a chance that the fuel level in the bowls is getting off level enough that it's causing problems? Just looking for another possibility. I'm not sure I follow this.=20 =20 =20 My thought is that we've all fixated on the bubbles as the cause of your troubles, but some bubbles shouldn't be a problem assuming you have "standard" carbs with fuel bowls, floats, etc. Bubbles flowing into a = fuel bowl should just get vented right out as fuel behind the bubble takes = it's place. If you have too many bubbles, eventually the fuel level in the = bowl will go down, and your mixture will lean out. Do you have a mixture = gauge? Can you tell if the mixture is going lean, or is it going rich? =20 If you had a needle/seat that was sticking open at times, you would have lower fuel pressure, and you would eventually overflow the bowl causing = your mixture to go rich. I believe you said your carbs were vented to the intake, so the overflow would (mercifully) be ingested by the engine, causing the mixture to be even more rich. As we know, the rotary can = run pretty darn well at high power on a very rich mixture, so this may not = be as obvious as you'd think. How about the times you say you reduced = throttle coming into the pattern and the engine quit? =20 =20 As for the carbs at climb attitude, carb bowls and floats are meant to = stay level (within reason). Tilting these to any extreme will cause an = apparent change in mixture. In the extreme, a float might stick open due to = friction caused by side loads on the float pivot at climb attitude. =20 =20 Basically, I'm just trying to give you something else to think about. A leak in a fuel line, pump, valve, etc, was certainly the leading possibility, but as many times as you've changed and re-arranged these items, I'm thinking they've been all but ruled out. =20 =20 One final thought- can you run on the center carb, and turn off the pump = for the outer carbs? =20 =20 Gotta go, Rusty =20 ------=_NextPart_000_0001_01C4D53E.D4E2AB90 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Message
For a=20 moment, let's assume that all your work on the fuel lines has proven = that=20 there's really no leak, or problems.  How about the carbs?  = Is there=20 a chance you have a needle/seat that's sticking partly open.  Is = there a=20 chance that the fuel level in the bowls is getting off level enough = that it's=20 causing problems?  Just looking for another=20 possibility.
I'm not sure I follow this. 
 
 
My thought is=20 that we've all fixated on the bubbles as the cause of = your troubles,=20 but some bubbles shouldn't be a problem assuming you have = "standard"=20 carbs with fuel bowls, floats, etc.  Bubbles flowing into = a fuel=20 bowl should just get vented right out as fuel behind the = bubble takes=20 it's place.   If you have too many bubbles, eventually the = fuel level=20 in the bowl will go down, and your mixture will lean out.   Do = you=20 have a mixture gauge?  Can you tell if the mixture is going lean, = or is it=20 going rich?
 
If you had a=20 needle/seat that was sticking open at times, you would have lower fuel = pressure,=20 and you would eventually overflow the bowl causing your mixture to go=20 rich.  I believe you said your carbs were vented to the intake, so = the=20 overflow would (mercifully) be ingested by the engine, causing the = mixture to be=20 even more rich.  As we know, the rotary can run pretty darn = well at=20 high power on a very rich mixture, so this may not be as obvious as = you'd=20 think.  How about the times you say you reduced throttle = coming into=20 the pattern and the engine quit?  
 
As for the=20 carbs at climb attitude, carb bowls and floats are meant to stay = level=20 (within reason).  Tilting these to any extreme will cause an = apparent=20 change in mixture.  In the extreme, a float might stick open due to = friction caused by side loads on the float pivot at climb = attitude.  =20
 
Basically,=20 I'm just trying to give you something else to think = about.  A=20 leak in a fuel line, pump, valve, etc, was certainly the leading=20 possibility, but as many times as you've changed and re-arranged these = items,=20 I'm thinking they've been all but ruled = out.  
 
One final=20 thought- can you run on the center carb, and turn off the pump for the = outer=20 carbs? 
 
Gotta=20 go,
Rusty
 
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