X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail05.syd.optusnet.com.au ([211.29.132.186] verified) by logan.com (CommuniGate Pro SMTP 5.1.12) with ESMTPS id 2356615 for flyrotary@lancaironline.net; Fri, 28 Sep 2007 01:55:46 -0400 Received-SPF: none receiver=logan.com; client-ip=211.29.132.186; envelope-from=lendich@optusnet.com.au Received: from george (d211-31-87-129.dsl.nsw.optusnet.com.au [211.31.87.129]) by mail05.syd.optusnet.com.au (8.13.1/8.13.1) with SMTP id l8S5t0gJ025996 for ; Fri, 28 Sep 2007 15:55:01 +1000 Message-ID: <001501c80194$23a71840$81571fd3@george> From: "George Lendich" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Carbs Date: Fri, 28 Sep 2007 15:55:12 +1000 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0012_01C801E7.F4375800" 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_0012_01C801E7.F4375800 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable 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) When we had SUs, we put motor oil in the slide dampers, and filed flat = spots on the back of the needle to change the fuel supply,and raise and = lower the needle in the slide. Most Race car stuff is just wide open = with good transition from zero throttle to wide open suddenly with no = missing. Aircraft is easier yet with 98% of the time at wide open, with = lots of time to write down O2 readings and EGTs to make changes later, = or tailor your leaning system. Lynn E. Hanover Lynn, I figure I will have to do some small mods to the needle, as I = progress. I was concerned about the starting point ( idle) and finishing = point ( wot) - I have revised my figures and feel now confident that I = will have enough fuel flow to make necessary adjustments. It took me 10 minutes to make the one needle, if I had to make several = more it's not a biggie. Even if for some crazy reason I run out of = thickness on 1/8", I can just step it up to a slightly bigger needle = with less grind depth. My design allows for continuous adjustment as the throttle opens, so I = shouldn't get into trouble by running too lean. I plan on using a O2 monitor to monitor the mixture at different RPM's = . I'm going back to the half circle slide cut-out to maintain a more = linier adjustment - it appears the better ones are using that method. Lynn, tell me why they use a notch on the slide. I have my own = opinions, but they may be totally wrong. George( down under) -------------------------------------------------------------------------= ----- See what's new at AOL.com and Make AOL Your Homepage. -------------------------------------------------------------------------= ----- No virus found in this incoming message. Checked by AVG Free Edition.=20 Version: 7.5.488 / Virus Database: 269.13.33/1034 - Release Date: = 27/09/2007 5:00 PM ------=_NextPart_000_0012_01C801E7.F4375800 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
 
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=20 slide carbs with the flat ground needle - have a needle size of 1/8" = (=20 3.175mm) and are ground to what appears to be = 'half' their=20 original size at WOT. My needle stock is 3.18mm, with sliding=20 tolerance, the needle seat/ jet is 3.23mm
 
That is the sized used for a 38mm = carb and I=20 was wondering if the 44mm carb might need a bigger needle, but I = don't know=20 how to calculate the main jet size/ fuel flow.
 
I have 13.1936 lbm (min of air) and = 1.043lbm=20 (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=20 size please, I just need to know if I'm in the ballpark or need to = go up in=20 needle size, if the depth of the grind exceeds 'half' the needle = size at=20 WOT.
 
George (down under)
 
 
When we had SUs, we put motor oil in the slide dampers, and filed = flat=20 spots on the back of the needle to change the fuel supply,and raise = and lower=20 the needle in the slide.  Most Race car stuff is just wide open = with good=20 transition from zero throttle to wide open suddenly with no missing. = Aircraft=20 is easier yet with 98% of the time at wide open, with lots of = time to=20 write down O2 readings and EGTs to make changes later, or tailor your = leaning=20 system.
 
Lynn E. Hanover


Lynn,
I figure I will have to do some small mods to the needle, as I = progress.=20 I was concerned about the starting point ( idle) and finishing point ( = wot) -=20 I have revised my figures and feel now confident that I will have = enough fuel=20 flow to make necessary adjustments.
It took me 10 minutes to make the one needle, if I had to make = several=20 more it's not a biggie. Even if for some crazy reason I run out of = thickness=20 on 1/8", I can just step it up to a slightly bigger needle with = less=20 grind depth.
My design allows for continuous adjustment as the throttle opens, = so I=20 shouldn't get into trouble by running too lean.
 
I plan on using a O2 monitor to monitor the mixture at different = RPM's=20 .
 
I'm going back to the half circle slide cut-out to maintain a = more linier=20 adjustment - it appears the better ones are using that = method.
 
Lynn, tell me why they use a notch on the slide. I have my = own=20 opinions, but they may be totally wrong.
 
George( down under)
See what's new at AOL.com=20 and Make AOL Your Homepage.

No virus found in this incoming message.
Checked by AVG Free = Edition.
Version: 7.5.488 / Virus Database: 269.13.33/1034 - = Release Date:=20 27/09/2007 5:00 PM
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