X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail34.syd.optusnet.com.au ([211.29.133.218] verified) by logan.com (CommuniGate Pro SMTP 5.1.12) with ESMTPS id 2354451 for flyrotary@lancaironline.net; Thu, 27 Sep 2007 03:13:02 -0400 Received-SPF: none receiver=logan.com; client-ip=211.29.133.218; envelope-from=lendich@optusnet.com.au Received: from george (d211-31-87-129.dsl.nsw.optusnet.com.au [211.31.87.129]) by mail34.syd.optusnet.com.au (8.13.1/8.13.1) with SMTP id l8R7CFK7026639 for ; Thu, 27 Sep 2007 17:12:17 +1000 Message-ID: <001f01c800d5$c419d340$81571fd3@george> From: "George Lendich" To: "Rotary motors in aircraft" Subject: Carbs Date: Thu, 27 Sep 2007 17:12:27 +1000 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_001C_01C80129.9456C2E0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2180 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 X-Antivirus: avast! (VPS 0657-0, 12/12/2006), Outbound message X-Antivirus-Status: Clean This is a multi-part message in MIME format. ------=_NextPart_000_001C_01C80129.9456C2E0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable 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_001C_01C80129.9456C2E0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

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 at=20 WOT. My needle stock is 3.18mm, with sliding tolerance, the needle = seat/=20 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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