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 5.2.14) with ESMTP id 3747667 for flyrotary@lancaironline.net; Tue, 07 Jul 2009 08:13:23 -0400 Received-SPF: pass receiver=logan.com; client-ip=75.180.132.121; envelope-from=eanderson@carolina.rr.com Received: from computername ([75.191.186.236]) by cdptpa-omta01.mail.rr.com with ESMTP id <20090707121231081.GRCC24657@cdptpa-omta01.mail.rr.com> for ; Tue, 7 Jul 2009 12:12:31 +0000 From: "Ed Anderson" To: "'Rotary motors in aircraft'" Subject: NKG SparkPlug Information Date: Tue, 7 Jul 2009 08:12:48 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0000_01C9FEDA.B77DA440" X-Mailer: Microsoft Office Outlook, Build 11.0.5510 Thread-Index: Acn+/D3oZ9IIO7J1QPKzopHEhwQGUA== X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5579 Message-Id: <20090707121231081.GRCC24657@cdptpa-omta01.mail.rr.com> This is a multi-part message in MIME format. ------=_NextPart_000_0000_01C9FEDA.B77DA440 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Here is some data I got off of the NKG sparkplug manufacture site that = may be of interest relative to SAG =20 Pre-delivery fouling Carbon fouling occurs when the spark plug firing end does not reach the self-cleaning temperature of approximately 450=B0C (842=B0F). Carbon = deposits will begin to burn off from the insulator nose when the self-cleaning temperature is reached. When the heat range is too cold for the engine speed, the firing end temperature will stay below 450=B0C and carbon = deposits will accumulate on the insulator nose. This is called carbon fouling. = When enough carbon accumulates, the spark will travel the path of least resistance over the insulator nose to the metal shell instead of jumping across the gap. This usually results in a misfire and further fouling. = If the selected spark plug heat range is too cold, the spark plug may = begin to foul when the engine speed is low or when operating in cold = conditions with rich air-fuel mixtures. In some cases, the insulator nose can = usually be cleaned by operating the engine at higher speeds in order to reach = the self-cleaning temperature. If the spark plug has completely fouled, and = the engine will not operate correctly, the spark plug may need to be cleaned = / replaced and the fouling cause identified. =20 Misfires * A misfire occurs when the spark travels the path of least = resistance instead of jumping across the gap. Misfires can be caused by the = following: 1. Carbon fouling=20 2. Worn or deteriorated ignition system components=20 3. Too large of gap size=20 4. Spark timing excessively advanced or retarded=20 5. Damaged spark plugs (cracked insulator, melted electrodes, etc) = 6. Mismatched ignition system components (plug resistance / wire resistance, ignition coils / igniter modules, etc.)=20 7. Insufficient coil primary and/or secondary voltage =96 voltage required to jump the spark plug gap higher than coil output=20 =20 This is what I found relative to Lead Fouling =20 Two types of lead fouling=20 1. Deposition of metallic lead or lead salts in the spark plug gap = causing a direct short. 2. Deposition of metallic lead or lead salts between the insulator and = the shell, gradually shortening the flashover path until misfiring occurs. Metallic lead deposits reduce the plug's shunt resistance.=20 Statistical Analysis of Airline Spark Plug fouling presented By Shell = Oil Company in 1950 The choice of operating variables could exert an appreciable effect on fouling. * The use of abnormally long rich-mixture idle periods=20 * Extremely lean mixture during cruise which results in poor combustion=20 * Low mixture temperatures and low cylinder head temperatures=20 _____ =20 =20 My interpretation of the above data still leads me to believe that = fouling is the most likely cause of SAG. But, of course, that is just my = opinion. =20 ED Ed Anderson Rv-6A N494BW Rotary Powered Matthews, NC eanderson@carolina.rr.com http://www.andersonee.com http://www.dmack.net/mazda/index.html http://www.flyrotary.com/ http://members.cox.net/rogersda/rotary/configs.htm#N494BW http://www.rotaryaviation.com/Rotorhead%20Truth.htm =20 =20 ------=_NextPart_000_0000_01C9FEDA.B77DA440 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

Here is = some data I got off of the NKG = sparkplug manufacture site that may be of interest relative to = =A0SAG

 

=

Pre-delivery = fouling

Carbon fouling occurs when the spark plug = firing end does not reach the self-cleaning temperature of approximately 450=B0C (842=B0F).  Carbon deposits will begin to burn off from the = insulator nose when the self-cleaning temperature is reached.  When the heat range = is too cold for the engine speed, the firing end temperature will stay below = 450=B0C and carbon deposits will accumulate on the insulator nose.  This is = called carbon fouling.  When enough carbon accumulates, the spark will = travel the path of least resistance over the insulator nose to the metal shell = instead of jumping across the gap.  This usually results in a misfire and = further fouling. 

If the = selected spark plug heat range is too cold, the spark plug may begin to foul when the engine = speed is low or when operating in cold conditions with rich air-fuel = mixtures.  In some cases, the insulator nose can usually be cleaned by operating = the engine at higher speeds in order to reach the self-cleaning = temperature.  If the spark plug has completely fouled, and the engine will not operate correctly, the spark plug may need to be cleaned / replaced and the = fouling cause = identified.    

Misfires

3D"*"       = A misfire occurs when the spark travels the path of = least resistance instead of jumping across the gap.  Misfires can be = caused by the following:

1.       Carbon fouling

2.       Worn or deteriorated ignition system components

3.       Too large of gap size

4.       Spark timing excessively advanced or retarded

5.       Damaged spark plugs (cracked insulator, melted electrodes, etc) =

6.       Mismatched ignition system components (plug resistance / wire resistance, ignition = coils / igniter modules, etc.)

7.       Insufficient coil primary and/or secondary voltage – voltage required to jump = the spark plug gap higher than coil output

 

This is what I found relative to Lead = Fouling

 

Two types of lead fouling =

1. Deposition of metallic lead or lead salts in the spark plug = gap causing a direct short.
2. Deposition of metallic lead or lead salts between the insulator and = the shell, gradually shortening the flashover path until misfiring occurs. = Metallic lead deposits reduce the plug's shunt resistance. =

Statistical Analysis of Airline Spark Plug fouling = presented By Shell Oil Company in 1950

The choice of operating variables could exert an appreciable = effect on fouling.

  • The use of abnormally long rich-mixture = idle periods
  • Extremely lean mixture during cruise = which results in poor combustion
  • Low mixture temperatures and low = cylinder head temperatures =

 

My interpretation of the above data still leads me to believe that fouling is the most likely cause of SAG.=A0 But, of course, = that is just my opinion.

 

ED

Ed Anderson

Rv-6A N494BW Rotary Powered

Matthews, NC

eanderson@carolina.rr.com

http://www.andersonee.com

http://www.dmack.net/mazda/index.html

http://www.flyrotary.com/

http://members.cox.net/rogersda/rotary/configs.htm#N494BW

http://www.r= otaryaviation.com/Rotorhead%20Truth.htm

 

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