X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from imo-d22.mx.aol.com ([205.188.144.208] verified) by logan.com (CommuniGate Pro SMTP 5.1.2) with ESMTP id 1596856 for flyrotary@lancaironline.net; Thu, 23 Nov 2006 09:35:41 -0500 Received-SPF: pass receiver=logan.com; client-ip=205.188.144.208; envelope-from=Lehanover@aol.com Received: from Lehanover@aol.com by imo-d22.mx.aol.com (mail_out_v38_r7.6.) id q.c9c.39a616d (58550) for ; Thu, 23 Nov 2006 09:35:16 -0500 (EST) From: Lehanover@aol.com Message-ID: Date: Thu, 23 Nov 2006 09:35:16 EST Subject: Re: [FlyRotary] Re: Spark Plug Fouling and Temperature To: flyrotary@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-----------------------------1164292516" X-Mailer: 9.0 Security Edition for Windows sub 5331 X-Spam-Flag: NO -------------------------------1164292516 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Content-Language: en =20 In a message dated 11/22/2006 10:27:56 P.M. Eastern Standard Time, =20 eanderson@carolina.rr.com writes: Never measured the trailing because its hole into the chamber is=20 too small to worry about any part of the electrode poking into the chamber= .. Ed This has to do with automotive racing use of the rotary engine. Some =20 information my not apply to aircraft use.=20 A question from the =E2=80=9CNo pistons list=E2=80=9D RE: Nonfoulers and the= trailing plug =20 holes. The recess looks and acts like the ages old cure for fouled plugs in=20 oil using motors.=20 I had a complete set of those nonfoulers on my old Chevy van. They worked so= =20 well that it would loose some porcelain from a tip now and then. (very high=20 nose temps) But they were working on a slightly different mechanism than th= e=20 same look in the rotary. The plug temps are somewhat controlled by the degr= ee=20 of exposure to the flame of the combustion chamber, and somewhat by the=20 distance the heat must flow from the plug shell to get to the cooling jacke= t and=20 be carried away.=20 The longer the path the hotter the plug runs. The nonfoulers had a broken=20 path at the plug threads into the nonfouler, and another at the plug thread= s in=20 the head, that was twice the thermal breaks of a stock plug. Nothing to do=20 with the heat range of the plug. Most of the path is designed into the head= or=20 rotor housing. How thick is the aluminum where the threads are cut through=20 the housing. How much coolant flows past this location and so on. The rest=20= of=20 the path is built into the plug, and that path length determines the plug's= =20 heat range.=20 This is very difficult to see on those plugs with the Mazda looking 360=20 degree ground electrode. Note here that Mazda plugs look just like aircraft= =20 plugs, and for the same reason. But on a more conventional plug you can see= how=20 long the center electrode insulator is before it joins the shell. In low=20 performance equipment the path is long so as to maintain high enough nose t= emps to=20 keep the plug clean and not foul up with carbon. Carbon is a conductor. It=20= is=20 what is used inside of resistors in electronic equipment. So a long heat=20 path means a hotter tip. A short path, as in the porcelain joins the shell=20= right=20 near the tip, means a colder plug and low nose temps. Using too cold a plug (low nose temps) for the performance situation, just=20 means too low a nose temp and this may lead to a carbon fouled plug. This i= s a=20 pain in the tailfeathers, but is cheap to cure. Using too hot a plug range=20 means high nose temps, and when the engine is used hard, may lead to =20 preignition from the white hot center electrode igniting the mixture before=20= the plug=20 fires (preignition). This can rapidly lead to detonation, and loss of the a= pex=20 seals. So, if you plan on missing the heat range, miss it to the low side. =20 Put in a colder plug than you think you need for the performance you plan to= =20 us. =20 In the olden times with the Kettering system, (where I came from), we used=20 to warm up the engine with real high heat range street plugs. Once the cool= ant=20 was up to temperature, we would shut down and switch to the ice cold racing= =20 plugs for the race. Everybody did this and it worked just fine. If there wa= s=20 a problem on the false grid that required a long shut down, there would be a= =20 good chance that one or two cars would foul plugs from having cooled off to=20 far and not be able to restart. If one of the street plugs was not changed=20= for=20 the race, the engine would be destroyed. Both, very unhappy situations. We need not do that anymore because we have the Mallory Hifire or MSD=20 ignition systems where we can insert over one amp of electrical energy into= the=20 plugs per thousand RPM. The rise times are so short and voltages are so hig= h,=20 that even a carbon fouled plug fires before the lower voltage of the old=20 Kettering system, (points or a points eliminator switch) can leak down acro= ss the=20 carbon path and misfire. Note also that these systems provide enough energy= =20 per strike to kill you. The MSD also fires once when you turn it on and onc= e=20 when you turn it off. If you don't want a Spiedel (watch band) shaped scar=20= on=20 your wrist, and a really bad memory, do not manipulate the plug wires with=20= the=20 battery connected. We use the NGK R6725-115 plugs, gapped at .010". They have a retracted gap=20 and fine wire electrodes. The heat range is ice cold. I have never fouled o= ne.=20 We use a MSD for leading and trailing. Even driving slowly to the false gri= d=20 on a cold morning, no problems. =20 =20 =20 Autolite and Champion both make plugs with a cold enough heat range to race= =20 in a NA rotary. We used Champion N57Gs for years. That is 3/4" reach medium tip gold=20 palladium center electrode. Whatever they say is the replacement for that p= lug=20 should work fine. A very cold plug. I forgot the Autolite number but I saw a box while rooting in the trailer=20 the other day. I will try to find them and publish that number. Auto Zone w= ill=20 order them under $7.00 a box of 4.=20 Always screw a new brand plug into a spare housing in both holes to be sure= =20 that there is no contact of the tip or threads running out in the hole.=20 Usually it is the extended tips that cause the problems. Also there is a sl= im =20 chance that the tip can extend into the chamber and destroy the apex seals.= You=20 wouldn't be the first to do it either. Look at everything. =20 OK I couldn't wait and went out to look. Frost on everything. the Autolite=20 number is AR2592. A little off ice cold. I rebuilt a rotary race engine tha= t=20 had 4 of these in it. No problems. And the price is right. I also noticed=20 several boxes of Champion N86. So they may have replaced the N57Gs from yea= rs=20 ago. Check with Champion on that. Somebody is always asking for plugs at the track, so I gave away the=20 Champions (we got for free) or the Autolites we got for $7.00 and I kept th= e NGKs=20 (we got for free for earning another invitation to the national championshi= ps). Rounded electrodes and missing porcelain? =20 Yes, obviously too high a heat range, and, or, too lean a mixture or advanc= e=20 for the RPM used. The trailing running a split timing gets more mixture in=20 its little chamber before it fires. The bigger the split, the more it gets.= So=20 it is exposed directly to the combustion process. The mixture when lit then= =20 reenters the chamber as a jet of fire, instead of just a spark, and that=20 works wonders for lighting the bigger charge in the chamber.=20 This trickery is used to help reduce the unburned hydrocarbons pollution=20 problem the rotary is famous for. It does not help power much, and it doesn= 't=20 hurt it much. Some builders drill out the little hole to about the same siz= e as=20 the leading hole. I never did it and I never saw one with that mod on the=20 dyno, so I cannot comment on the power it might or might not generate.=20 A housing that has been damaged by too hot a heat range plug, or long time=20 running close to over heated, will get a tiny crack across the little hole.= So=20 long as it cannot be felt, or no surface appearance changes around the crac= k=20 shows up like the apex seals are stressing the area, there is no need to=20 repair anything. However if there is evidence of a step or chrome changing color, the surfac= e=20 may be reduced with a stone and the housing reused barring any other=20 problem. The apex seal will tolerate a depression but not a bump. A housing with radial cracks (in all directions) from the little hole=20 indicates a bigger overheating incident and greater care must be used and e= xtensive=20 inspection of the housing for distortion and so on must be conducted before= =20 reuse. Lynn E. Hanover -------------------------------1164292516 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Content-Language: en
In a message dated 11/22/2006 10:27:56 P.M. Eastern Standard Time,=20 eanderson@carolina.rr.com writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>Never=20 measured the trailing because its hole into the chamber is
too small t= o=20 worry about any part of the electrode poking into the=20 chamber..

Ed
 =20

This has to do with automotive racing use of the rotary engine. Some=20 information my not apply to aircraft use.

A question from the =E2=80=9CNo pistons list=E2=80=9D RE: Nonfoulers and=20= the trailing plug=20 holes. The recess looks and acts like the ages old cure for fouled plugs in=20= oil=20 using motors.


I had a complete set of those nonfoulers on my old Chevy van. They worked= so=20 well that it would loose some porcelain from a tip now and then. (very high=20= nose=20 temps) But they were working on a slightly different mechanism than the same= =20 look in the rotary. The plug temps are somewhat controlled by the degree of=20 exposure to the flame of the combustion chamber, and somewhat by the distanc= e=20 the heat must flow from the plug shell to get to the cooling jacket and be=20 carried away.

The longer the path the hotter the plug runs. The=20 nonfoulers had a broken path at the plug threads into the nonfouler, and ano= ther=20 at the plug threads in the head, that was twice the thermal breaks of a stoc= k=20 plug. Nothing to do with the heat range of the plug. Most of the path is=20 designed into the head or rotor housing. How thick is the aluminum where the= =20 threads are cut through the housing. How much coolant flows past this locati= on=20 and so on. The rest of the path is built into the plug, and that path length= =20 determines the plug's heat range.

This is very difficult to see on t= hose=20 plugs with the Mazda looking 360 degree ground electrode. Note here that Maz= da=20 plugs look just like aircraft plugs, and for the same reason. But on a more=20 conventional plug you can see how long the center electrode insulator is bef= ore=20 it joins the shell. In low performance equipment the path is long so as to=20 maintain high enough nose temps to keep the plug clean and not foul up with=20 carbon. Carbon is a conductor. It is what is used inside of resistors in=20 electronic equipment. So a long heat path means a hotter tip. A short path,=20= as=20 in the porcelain joins the shell right near the tip, means a colder plug and= low=20 nose temps.

Using too cold a plug (low nose temps) for the performanc= e=20 situation, just means too low a nose temp and this may lead to a carbon foul= ed=20 plug. This is a pain in the tailfeathers, but is cheap to cure. Using too ho= t a=20 plug range means high nose temps, and when the engine is used hard, may lead= to=20 preignition from the white hot center electrode igniting the mixture before=20= the=20 plug fires (preignition). This can rapidly lead to detonation, and loss of t= he=20 apex seals. So, if you plan on missing the heat range, miss it to the low si= de.=20 Put in a colder plug than you think you need for the performance you plan to= us.=20

In the olden times with the Kettering system, (where I came from), w= e=20 used to warm up the engine with real high heat range street plugs. Once the=20 coolant was up to temperature, we would shut down and switch to the ice cold= =20 racing plugs for the race. Everybody did this and it worked just fine. If th= ere=20 was a problem on the false grid that required a long shut down, there would=20= be a=20 good chance that one or two cars would foul plugs from having cooled off to=20= far=20 and not be able to restart. If one of the street plugs was not changed for t= he=20 race, the engine would be destroyed. Both, very unhappy situations.

W= e=20 need not do that anymore because we have the Mallory Hifire or MSD ignition=20 systems where we can insert over one amp of electrical energy into the plugs= per=20 thousand RPM. The rise times are so short and voltages are so high, that eve= n a=20 carbon fouled plug fires before the lower voltage of the old Kettering syste= m,=20 (points or a points eliminator switch) can leak down across the carbon path=20= and=20 misfire. Note also that these systems provide enough energy per strike to ki= ll=20 you. The MSD also fires once when you turn it on and once when you turn it o= ff.=20 If you don't want a Spiedel (watch band) shaped scar on your wrist, and a re= ally=20 bad memory, do not manipulate the plug wires with the battery=20 connected.

We use the NGK R6725-115 plugs, gapped at .010". They have= a=20 retracted gap and fine wire electrodes. The heat range is ice cold. I have n= ever=20 fouled one. We use a MSD for leading and trailing. Even driving slowly to th= e=20 false grid on a cold morning, no problems.


Autolite and Champion both make plugs with a cold en= ough=20 heat range to race in a NA rotary.
We used Champion N57Gs for years= .=20 That is 3/4" reach medium tip gold palladium center electrode. Whateve= r=20 they say is the replacement for that plug should work fine. A very col= d=20 plug.

I forgot the Autolite number but I saw a box while rootin= g in=20 the trailer the other day. I will try to find them and publish that=20 number. Auto Zone will order them under $7.00 a box of 4.

Alwa= ys=20 screw a new brand plug into a spare housing in both holes to be sure t= hat=20 there is no contact of the tip or threads running out in the hole. Usu= ally=20 it is the extended tips that cause the problems. Also there is a slim=20 chance that the tip can extend into the chamber and destroy the apex=20 seals. You wouldn't be the first to do it either. Look at everything.=20


OK I couldn't wait and went out to look. Frost on everythi= ng.=20 the Autolite number is AR2592. A little off ice cold. I rebuilt a rota= ry=20 race engine that had 4 of these in it. No problems. And the price is=20 right. I also noticed several boxes of Champion N86. So they may have=20 replaced the N57Gs from years ago. Check with Champion on=20 that.

Somebody is always asking for plugs at the track, so I ga= ve=20 away the Champions (we got for free) or the Autolites we got for $7.00= and=20 I kept the NGKs (we got for free for earning another invitation to the= =20 national championships).


Rounded electrodes and missing=20 porcelain?


Yes, obviously too high a heat range, and, or, too l= ean a=20 mixture or advance for the RPM used. The trailing running a split timi= ng=20 gets more mixture in its little chamber before it fires. The bigger th= e=20 split, the more it gets. So it is exposed directly to the combustion=20 process. The mixture when lit then reenters the chamber as a jet of fi= re,=20 instead of just a spark, and that works wonders for lighting the bigge= r=20 charge in the chamber.

This trickery is used to help reduce th= e=20 unburned hydrocarbons pollution problem the rotary is famous for. It d= oes=20 not help power much, and it doesn't hurt it much. Some builders drill=20= out=20 the little hole to about the same size as the leading hole. I never di= d it=20 and I never saw one with that mod on the dyno, so I cannot comment on=20= the=20 power it might or might not generate.

A housing that has been=20 damaged by too hot a heat range plug, or long time running close to ov= er=20 heated, will get a tiny crack across the little hole. So long as it ca= nnot=20 be felt, or no surface appearance changes around the crack shows up li= ke=20 the apex seals are stressing the area, there is no need to repair=20 anything.

However if there is evidence of a step or chrome chan= ging=20 color, the surface may be reduced with a stone and the housing reused=20 barring any other problem. The apex seal will tolerate a depression bu= t=20 not a bump.

A housing with radial cracks (in all directions) fr= om=20 the little hole indicates a bigger overheating incident and greater ca= re=20 must be used and extensive inspection of the housing for distortion an= d so=20 on must be conducted before reuse.

Lynn E.=20 Hanover



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