X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml Date: Sun, 17 Sep 2006 22:57:22 -0400 Message-ID: X-Original-Return-Path: Received: from sfa.gami.com ([68.89.254.162] verified) by logan.com (CommuniGate Pro SMTP 5.1c.4) with ESMTP id 1406044 for lml@lancaironline.net; Sat, 16 Sep 2006 13:49:20 -0400 Received-SPF: none receiver=logan.com; client-ip=68.89.254.162; envelope-from=gwbraly@gami.com Received: from localhost (localhost.localdomain [127.0.0.1]) by sfa.gami.com (Postfix) with ESMTP id EAAB329C06E for ; Sat, 16 Sep 2006 12:48:38 -0500 (CDT) Received: from sdf1.mail.taturbo.com (unknown [10.10.10.173]) by sfa.gami.com (Postfix) with ESMTP id C959329C05E for ; Sat, 16 Sep 2006 12:48:36 -0500 (CDT) Content-class: urn:content-classes:message MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----_=_NextPart_001_01C6D9B8.56016B5D" X-MimeOLE: Produced By Microsoft Exchange V6.0.6603.0 Subject: LOP and cylinder wear - - X-Original-Date: Sat, 16 Sep 2006 12:48:36 -0500 X-Original-Message-ID: X-MS-Has-Attach: X-MS-TNEF-Correlator: Thread-Topic: LOP and cylinder wear - - Thread-Index: AcbYA6sMBKNT6HUrSf28NpWyD1quVgBs5TeQ From: "George Braly" X-Original-To: "Lancair Mailing List" X-Virus-Scanned: by amavisd-new-2.3.2 (20050629) (Debian) at gami.com This is a multi-part message in MIME format. ------_=_NextPart_001_01C6D9B8.56016B5D Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable =20 Jim Hergert writes: =20 =20 >>As a side bar, I don't run LOP anymore unless I need to stretch the range. This after replacing all 6 cylinders at 215 hrs from new and then the second set after only 82 hrs. Both times the exhaust valve stems and guides were out of serviceable tolerance. This could be a very long thread but will have to wait. << =20 Jim, you have to stay focused on the science of this. It is easy to let anecdotal information or isolated personal experiences like yours overwhelm the decision making process. =20 Consider, I can show you an 87 hour factory NEW TCM engine on a NEW airframe from about 18 months ago that has exhaust valve stem/guides worn out. Engine was operated ROP for the whole time. =20 =20 TCM claims they have revised that configuration and now post-ream the valve guides - - and that should fix the problem.=20 =20 =20 So, what were your cylinders? TCM's? Somebody else's ? Overhauls? What is the history? =20 So far as I know, there is absolutely no evidence or even any well considered engineering/scientific hypothesis as to why operating an engine at 75% power at 50 to 100dF ROP should be "better" for the exhaust valve guides as compared to operating the same engine a the same horsepower with the mixture set to 50 to 75dF LOP. =20 =20 There is lots of evidence that poor dimensional fits for valve guides and stems and seats causes the precise problem you experienced. =20 Regards, George ------_=_NextPart_001_01C6D9B8.56016B5D Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable

 

Jim = Hergert writes:

 

 

>>As a side bar, I don't run LOP anymore unless I need to = stretch the range. This after replacing all 6 cylinders at 215 hrs from new and = then the second set after only 82 hrs. Both times the exhaust valve stems and = guides were out of serviceable tolerance. This could be a very long thread but = will have to wait. = <<

 

Jim,  you have to stay focused = on the science of this.  It is easy to let anecdotal information or = isolated personal experiences like yours overwhelm the decision making = process.

 

Consider,  I can show you an = 87 hour factory NEW TCM engine on a NEW airframe from about 18 months ago that = has exhaust valve stem/guides worn out.  Engine was operated ROP = for  the whole time. 

 

TCM = claims they have revised that configuration  and now = post-ream the valve guides - - and that should fix the problem. =

 

 

So,  what were your = cylinders?   TCM’s?  Somebody else’s ?  Overhauls?  What is the = history?

 

So far as I know,  there is = absolutely no  evidence or even any well considered engineering/scientific hypothesis = as to why operating an engine at 75% power at 50 to 100dF  ROP should be = “better” for the exhaust valve guides as compared to operating the same engine a = the same horsepower with the mixture set to 50 to 75dF LOP. =  

 

There is lots of evidence that poor dimensional fits for valve guides and stems and seats causes the precise problem you experienced.

 

Regards,  = George

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