X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from cdptpa-omtalb.mail.rr.com ([75.180.132.121] verified) by logan.com (CommuniGate Pro SMTP 5.1.12) with ESMTP id 2354880 for flyrotary@lancaironline.net; Thu, 27 Sep 2007 08:32:35 -0400 Received-SPF: pass receiver=logan.com; client-ip=75.180.132.121; envelope-from=eanderson@carolina.rr.com Received: from edward2 ([24.74.103.61]) by cdptpa-omta01.mail.rr.com with SMTP id <20070927123156.OPWK4058.cdptpa-omta01.mail.rr.com@edward2> for ; Thu, 27 Sep 2007 12:31:56 +0000 Message-ID: <000e01c80102$8b952970$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Carbs Date: Thu, 27 Sep 2007 08:33:01 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_000B_01C800E1.04480710" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.3138 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3138 This is a multi-part message in MIME format. ------=_NextPart_000_000B_01C800E1.04480710 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable George, you're going to have to ask someone who has experience with = carburetors - I went with fuel injection because of the very frustrating = experience I had trying to tune a Webber carburator with all its = different size air bleeds and jets. I just found EFI was much easier = to know what I was getting. Not against carburetors, they obviously = work quite well - if you know what you are doing with all the jets and = air bleeds - which I clearly did not. Perhaps Bill J can help. Ed ----- Original Message -----=20 From: George Lendich=20 To: Rotary motors in aircraft=20 Sent: Thursday, September 27, 2007 3:12 AM Subject: [FlyRotary] Carbs Ed, I have another one for you! I am currently copying some of the parts of different carbs to cobble = together my own design. I found info that the slide carbs with the flat = ground needle - have a needle size of 1/8" ( 3.175mm) and are ground to = what appears to be 'half' their original size at WOT. My needle stock is = 3.18mm, with sliding tolerance, the needle seat/ jet is 3.23mm That is the sized used for a 38mm carb and I was wondering if the 44mm = carb might need a bigger needle, but I don't know how to calculate the = main jet size/ fuel flow. I have 13.1936 lbm (min of air) and 1.043lbm (min of fuel) at 12.65:1 = fuel ratio, at 7,500 rpm (WOT). Can you show me how to work out the main jet size please, I just need = to know if I'm in the ballpark or need to go up in needle size, if the = depth of the grind exceeds 'half' the needle size at WOT. George (down under) ------=_NextPart_000_000B_01C800E1.04480710 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
George, you're going to have to ask someone who = has=20 experience with carburetors - I went with fuel injection because of the = very=20 frustrating experience I had trying to tune a Webber carburator with all = its=20 different size air bleeds and jets.   I just found EFI was = much easier=20 to know what I was getting.  Not against carburetors, they = obviously work=20 quite well - if you know what you are doing with all the jets and air = bleeds -=20 which I clearly did not.
 
Perhaps Bill J can help.
 
Ed
----- Original Message -----
From:=20 George=20 Lendich
Sent: Thursday, September 27, = 2007 3:12=20 AM
Subject: [FlyRotary] = Carbs

Ed,
I have another one for = you!
I am currently copying some of the = parts of=20 different carbs to cobble together my own design. I found info that = the slide=20 carbs with the flat ground needle - have a needle size of 1/8" ( = 3.175mm) and=20 are ground to what appears to be 'half' their = original size=20 at WOT. My needle stock is 3.18mm, with sliding tolerance, the = needle=20 seat/ jet is 3.23mm
 
That is the sized used for a 38mm = carb and I was=20 wondering if the 44mm carb might need a bigger needle, but I don't = know how to=20 calculate the main jet size/ fuel flow.
 
I have 13.1936 lbm (min of air) and = 1.043lbm (min=20 of fuel) at 12.65:1 fuel ratio, at 7,500 rpm (WOT).
 
Can you show me how to work out the = main jet size=20 please, I just need to know if I'm in the ballpark or need to go up in = needle=20 size, if the depth of the grind exceeds 'half' the needle size at=20 WOT.
 
George (down under)
 
 
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