X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sat, 14 Apr 2012 00:01:40 -0400 Message-ID: X-Original-Return-Path: Received: from nm3-vm2.bullet.mail.ne1.yahoo.com ([98.138.91.19] verified) by logan.com (CommuniGate Pro SMTP 5.4.4) with SMTP id 5478519 for lml@lancaironline.net; Thu, 12 Apr 2012 08:54:12 -0400 Received-SPF: none receiver=logan.com; client-ip=98.138.91.19; envelope-from=casey.gary@yahoo.com Received: from [98.138.90.53] by nm3.bullet.mail.ne1.yahoo.com with NNFMP; 12 Apr 2012 12:53:36 -0000 Received: from [98.138.89.199] by tm6.bullet.mail.ne1.yahoo.com with NNFMP; 12 Apr 2012 12:53:36 -0000 Received: from [127.0.0.1] by omp1057.mail.ne1.yahoo.com with NNFMP; 12 Apr 2012 12:53:36 -0000 X-Yahoo-Newman-Property: ymail-3 X-Yahoo-Newman-Id: 158765.2063.bm@omp1057.mail.ne1.yahoo.com Received: (qmail 778 invoked by uid 60001); 12 Apr 2012 12:53:36 -0000 DomainKey-Signature:a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=X-YMail-OSG:Received:X-Mailer:References:Message-ID:Date:From:Reply-To:Subject:To:In-Reply-To:MIME-Version:Content-Type; b=B8h1+MG6fm/3LH5rPChUA0kF0V5vJjJRkjlJfFLzTEgnkgLqaj18nzOIZ3dcG9KokzkutvvUG+dKYYfOtTz7o3X+HUQ5l74vIzGEU5yFKaEAdsjdsKjTlbbcwXra2ttHM+eGpi9pmDiZbCxIuyRPY7y8nfXMm19VJjsX9+roizc=; X-YMail-OSG: 7jKi0TAVM1kGj8MNiTSS9H9HKtu1Nhzw9WYlF7d7e0MF7W5 q7481wCVUX5mSG41W9J_tEI5C0xGQPxiVADrmQPP2LiRGFtI810_2cqVgmWa Jf_h0scLydQ2InoY5fOAsr5mnKq.sYteHQ1obs.VJ4nc3y6C2bKrFqgi8tJu iGEDhHuyDSSx0p1kFekXuFcMH5G9iW8hL3LcGPczbWnw.yBeKmD2APldfZRq LL168ep348MOG3993t5zRbzfab2Sdh1g79OsIg6XYSslNL1_uVojIFWHQaRo wR0bTEdtZsKaWDDnE5nLwMXB7emtWB4Fl8c.MfupGxI39uC72RCLs_iWg.TK HK5gVdPyarzY_eKjannkDVqJ3p2ZkioV6KM.UR7Ni_v2O3HTkRrPLQubakwB NJ6bkiZEZ1FrHUtcrnHT.NekeZW8fbxMfryllH2q3nDltD08V8RHcvnqP98Z e Received: from [71.218.243.137] by web125603.mail.ne1.yahoo.com via HTTP; Thu, 12 Apr 2012 05:53:35 PDT X-Mailer: YahooMailWebService/0.8.117.340979 References: X-Original-Message-ID: <1334235215.99054.YahooMailNeo@web125603.mail.ne1.yahoo.com> X-Original-Date: Thu, 12 Apr 2012 05:53:35 -0700 (PDT) From: Gary Casey Reply-To: Gary Casey Subject: Re: P lead X-Original-To: Lancair Mailing List In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="933233344-1334681465-1334235215=:99054" --933233344-1334681465-1334235215=:99054 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable I'm in digest mode, so pardon me if I'm explaining something that has alrea= dy been "splained."=0AThe Primary circuit is very simple - the primary coil= winding is grounded on one end and the other is connected to the points, w= hich are grounded, and to the "P" lead terminal. =A0The magnet spins by and= with the points closed current builds up in the primary coil. =A0Then the = points open, stopping the current flow. =A0This causes an inductive surge (= high voltage - about 100+ volts), which is then transformed by the secondar= y winding to spark plug voltage. =A0All the ignition switch does is permane= ntly ground the primary coil in parallel with the points, preventing the vo= ltage surge. =A0The resistance of the primary coil is very low, less than 1= ohm. =A0If you read the resistance to ground you will get a zero reading i= f the points happen to be closed and a very low reading, usually mistaken a= s zero, when the points are open. =A0Sorry for the long explanation, but wh= at you are reading is probably normal.=0A=0AI use a simple ohmmeter to set = timing, but noting the very slight difference when the points open. =A0But = the prop has to be turned very slowly or the voltage surge will make the me= ter go kablooey.=0AGary Casey=0A=0A=0A=0AI tried to start my IO360 today an= d discovered that the P-lead on the Slick magneto seemed to be shorted to g= round.=A0 When I diagnosed with a vom, I found that the p-lead stud on the = mag IS a ground.=A0 My question:=A0 what is the point of grounding the P-le= ad if it is ground already?=A0 This is a new mag run only one hour at Super= ior on test stand.=A0 Someone please explain.=0AEd Gray=A0 Dallas --933233344-1334681465-1334235215=:99054 Content-Type: text/html; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable
I'm in digest = mode, so pardon me if I'm explaining something that has already been "splai= ned."
The Primary circuit is very simple - the primary coil windi= ng is grounded on one end and the other is connected to the points, which a= re grounded, and to the "P" lead terminal.  The magnet spins by and wi= th the points closed current builds up in the primary coil.  Then the = points open, stopping the current flow.  This causes an inductive surg= e (high voltage - about 100+ volts), which is then transformed by the secon= dary winding to spark plug voltage.  All the ignition switch does is p= ermanently ground the primary coil in parallel with the points, preventing = the voltage surge.  The resistance of the primary coil is very low, le= ss than 1 ohm.  If you read the resistance to ground you will get a zero reading if the points happen to be closed and a very low reading, u= sually mistaken as zero, when the points are open.  Sorry for the long= explanation, but what you are reading is probably normal.

I use a simple ohmmeter to set timing, but noting the very slight = difference when the points open.  But the prop has to be turned very s= lowly or the voltage surge will make the meter go kablooey.
Gary = Casey


I tried to start my I= O360 today and discovered that the P-lead on the Slick magneto seemed to be sho= rted to ground.  When I diagnosed with a vom, I found that the p-lead = stud on the mag IS a ground.  My question:  what is the point of = grounding the P-lead if it is ground already?  This is a new mag run o= nly one hour at Superior on test stand.  Someone please explain.
Ed Gray  Dallas
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