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From: John De Armond
X-Source: The Hotrod Mailing list
Date: Jun 1992
Subject: Re: ignition questions

>I am currently using Bosh Platinum plugs.  I have seen some ads for
>"splitfile" spark plugs.  These plugs cost between $5 and $6 each.  Are
>these plugs worth the cost in increased performance and mileage??

Weeellll they might be better than the Bosch plugs.. But so would ordinary
Champions or Autolites or whatever.  Bosch "platinum" (I quote because
the amount of platinum would require a microbalance to measure) are
the worst plugs I've ever tried to use.  REAL platinum plugs are
made by NGK, among others and cost upwards of $10 each.  Platinum is a
precious metal, after all.  On the good side, they last forever.
The OEM plugs are still in my wife's Toyota Camry with 70,000 miles.
Good thing too, cuz the intake has to come off to change the rear bank.

About "splitfire" plugs, I suppose they work if "work" is defined as
getting people to open their wallets and pay 5 prices for a sparkplug.
If you want to see of the principle works (hint: it doesn't),
just take some regular plugs and split the ground electrode with a
strong pair of dykes or a slitting wheel in a Dremel tool.

>I am also thinking about purchasing an ignition system from Jacobs
>Electronics called an "Energy Team".  Does anyone have any experience
>with this system??

Only second hand.  Frankly the Jacob's "from the Dr." bullshit is more
than I can swallow.  I have their media kit and it make me want to
put on gloves, it is so loaded with BS.  I can't tell whether it does
anything special or not because the literature they send out is
so full of hype.  I'm going to get one in here to review soon and get
to the bottom of the hype.

For less money you can get a system that is known to work and is proven
daily and weekly by thousands of racers.  That is the MSD system.
I particularly like the MSD concept because I discovered the same
principle - that multiple and/or extremely highly energetic spark
is worth real power - as part of a science fair project almost 25
years ago.  Over a broad range, the more spark energy the better.
the MSD-6AL (or MSD-6T if you don't need a rev limiter) is an excellent
box that only costs about $130 from Summit Racing.  I have one on
all my high performance cars and love 'em.  You will have to run MSW
wires with the MSD box, as the energetic spark will quickly degrade
resistance wires.

I have used the Mallory Hyfire and the Allison systems but I've
never found anything better than the MSD box, particularly for the money.


From: John De Armond
X-Source: The Hotrod Mailing list
Date: Jun 1992
Subject: Re: Plug codes

>Anyone know how to decode spark plug heat range codes for
>the major manufacturers?
>In the dim recesses of my mind, I seem to recall that the
>plugs I normally use (BP6ES, by I think Champion) are
>coded in such a way that the temperature of the heat
>range is directly proportional to the number in the string.
>That is, a BP7ES would be one range hotter, while a BP5ES
>would be one range cooler.  Izzat so, or do I have it sdrawkcab?

I used to have the charts between Champion and NGK memorized.
NGK numbers ascend for colder plugs and Champion descend.
That BP6ES is an NGK number and would be equivalent to,
oh, probably an N-11Y Champion (strictly from foggy memory.)
Man, I hope I got that right :-)

Both vendors have cross reference charts available for the
asking.  My experience has been that NGKs are broader in heat
range and more resistant to fouling than Champions.  Not enough
experience with any other brand to comment.  Other than Bosch
Platinums (sic) with are fecal matter.

>Racers, of course, typically run one range cooler because
>it allows (or allowed) dialing in a skoosh more spark advance.
>The cooler plugs would dissipate heat better, thereby helping
>avoid some of the knock problems that came about with lots of
>spark advance and also helped move a tiny bit of the combustion
>temperature into the head more quickly than the hotter plugs,
>at some expense in a tendency to foul.

More a matter of load profile than spark advance.  If you slog around
at 2000 rpm in traffic, you run hotter plugs than if you live
at 7000 rpm.  If you've got an oiler and don't plan on trying to
break the motor, several heat ranges hotter is safe.  If it's
really fouling, try one of the no-foul plug adaptors.  They work
but they'll burn a hole through a plug in a healthy cylinder.

>Actually, with modern ignition systems, mass airflow sensors,
>knock detection algorithms and the rest, I wouldn't be surprised
>to learn that tweaking the plugs' heat range doesn't get you
>much of anything any more.  But the cars in question are from
>1965 and 1967, so vintage advice will be right at home.

So put an MSD box on the thing and forget about it :-)

73 John

From: John De Armond
X-Source: The Hotrod Mailing list
Date: Jun 1992
Subject: Re: Plugs

> I don't really have anything against Champion per se, but their quality
>control stinks.

And has for 20 years, unfortunately.

> I realize many people have run nothing but Champions for years and
>never had a lick of trouble; bear in mind all the rejects have to go
>somewhere, and evidently they box 'em up and send 'em to Little Rock.

They send some of 'em to Tennessee too.  You've heard the old racer's
maxim "Never start a race on new plugs"?  The guy who invented that was
thinking about Champion.  My favorite has become NGK because the heat
range seems to be the broadest for a given heat number.


From: John De Armond
X-Source: The Hotrod Mailing list
Subject: Re: spark plug washers
Date: Wednesday, Jul 01 1992 16:01:58
X-Sequence: 1455

>Last night when reading thru some old hotrod mags i have, i came across
>an ad for sized washers that you put on your spark plugs to assure the
>plug gap is facing the proper direction for maximum burn of the air-fuel
>mixture.  Does anyone out there know if this really helps performance and
>if so how much??

The purpose of indexing plugs is to a) place the ground electrode where it
will cause the least disturbance to flow and b) where there will be
maximum exposure to the mixture flow at the instant of ignition.
The direction of mixture flow is variable and may even change with RPM
and tuned header/intake action.

Like a lot of other things you can do, indexing the plugs may or may
not help your particular engine.  The only way you can discover
whether it helps or not is to try it and carefully record the results.
Note that extensive testing may be required because the proper direction -
if any - of the ground electrode must also be determined experimentally.
This is absolutely not a "bolt'n'pray" type of tuning tool.


From: John De Armond
X-Source: The Hotrod Mailing list
Date: Aug 1992
Subject: Plug gap

>The question of gap on Jeffs Jacobs system brings to mind the same
>question I have on my MSD 6_T. The instructions make no mention of this
>specification. What would be the recommended gap? I am currently running
>.045 and think that going to .060 would be good. But my motor is now
>running 9.21:1 compression and I don't think that there would really be
>much benefit, but if I get the turbo setup and run ~12-15 lbs. then I am
>out of my area. Could someone give me some information on this subject?

My BS alarm goes on red alert everytime I hear from "Dr. Jacobs".  I'm
about to get one of the boxes and do a tech review on it in order to
strip off all the hype.  I particularly intend to evaluate this metal
replating claim.  I have very serious doubts about this happening based
on observing the ignition process through a pyrex head on a test

RE Bosch Platinum plugs.  Garbage.  I think they're skirting the limit of
the law in claiming that the tiny speck of platinum on the end of
the electrode constitutes a "platinum plug."  I tried some of these in
my BMW and in my Z.  In both cases, they would foul at the least excuse.
The BMW burned the electrode all the way out of sight inside 15,000 miles.
I took them out of the Z before that could happen.

Platinum costs more  per ounce than gold so if you're going to
buy real platinum plugs, you're going to pay for them.  I've
mentioned the ND/NGK plugs  used in my wife's Toyota before.
75,000 miles and still going strong. The electrode in this plug
is solid platinum and tapers down to a sharp point that has not
eroded in this mileage.  They cost about $8 each from Toyota.
I'm pretty sure Bosch makes a real platinum plug too, because
they were used (still are?) in Porches.  These $1.95 K-mart
specials  ain't the critters.

Regarding plug gap, the MSD has more than enough voltage reserve to fire
most any possible gap.  The problem is getting the gap so wide the spark
arcs across the insulator to the shell.  Not good for ignition or anti-
fouling.  I experimentally set the gap on my turbo engine.  This involved
varying the gap in a pressurized chamber (like used to be on the champion
plug cleaning and testing machines) until the spark took the alternate
route.  I'm not sure what the gap is but the center electrode cants
at about a 30 degree angle.

The results I was looking for and got were better idle with marginal
mixtures and better mileage as the result of better ignition at
part throttle.  The only downside is the stock system may not be able
to handle the added voltage stress.  I've heard of rotor buttons blasting
through to the shaft from the added stress.


From: John De Armond
X-Source: The Hotrod Mailing list
Date: Aug 1992
Subject: Re: Plug gap

>-> varying the gap in a pressurized chamber (like used to be on the
>-> champion plug cleaning and testing machines) until the spark took the
> Gosh, I haven't seen one of those things in years.
> I seem to remember some controversy over the plug cleaning machines.
>Do they really work?  I realize only a file or a pass with the moto-tool
>will give nice sharp corners on the electrodes like a new plug, but it
>always looked like it'd be useful to turn the insulator white again so I
>could see the results of the next jet change/boost increase/whatever.

Official Champion word and my experience is that those things, which use
abrasive sand, remove the glaze from the porcelean and thus make the
plug extremely foul-prone.

What I've found to work quite well, however, to whiten a plug up for another
check is to GENTLY bead blast the porcelean.  40 psi air or less.


From: emory!!jjnjw
X-Source: The Hotrod Mailing list
Date: Jul 1993
Subject: help: sparks plugs hot/cold
X-Sequence: 5808

Hello ..

I was looking thru my owners manual ( '90 miata) and I noticed they had
3 different plugs listed for my car ..  as it turns out ..  the extremes
are hot or cold plugs..  Please explain the difference and when you
should use a hot plug or a cold plug

[The cold plug would be approrpiate for extended wide open throttle.
By extended I mean several miles at a time.  The hot plug would be for
conditions such as very extended idling where fouling might be a problem.
The middle plug is for average service.  JGD]

AND ..

When i race the car (auto crossing) ...  should i use a different plug
then what i would use when i am driving on the street ?

I don't mind changing the plugs when I get to the "event" and then
changing again before i drive home ..  IF one plug type is better then
another for tre particular use...  Some one told me that : If your plug
electrodes are 'white' then you need a colder plug and If they are
black/carbon-coated ..  then I should use a hotter plug ..  I have NO
idea ...

[I wouldn't bother changing plugs in a (mostly) stock engine.  Modern
plugs have a fairly wide heat range and coupled with closed loop engine
management, you're unlikely to have any fouling problems.  You really
can't read much from plug color with unleaded gas.  IT just doesn't color
the plug like leaded fuel used to.  JGD]

Please post here  OR write to me directly ..
 James D. Wynn

thanks in advance ...

From: (Bruce Hamilton)
Subject: Re: "Hot" vs "Cold" plugs??
Date: Mon, 01 Sep 1997 18:47:47 GMT

Well, I thought I would see if anyone actually read my posts
by mixing up two major parameters for spark plug heat ranges
( length of exposed central electrode, and length of the heat
transfer region ) in the ascii drawings. Nobody noticed, even
though the drawings looked unbalanced. Altavoz followed up
- without detecting the deliberate error - as I expected, but
I though some of the obvious clue-laden readers might have.

Ah well, the correct drawings are below, and I've added to them
to show where the threaded portion is relative to the heat transfer
area, as the seat and threads are the major paths of heat transfer.
Obviously the overall heat range of the tip results from the balance
between the heat dissipated from the tip versus the heat transferred
to the tip from combustion and the plug body, which is greatly affected
by the design ( amount of exposed electrode, electrode material and
diameter, overall heat retention of the plug body, overall thermal
mass and conductivity of plug body, etc.etc. ).

It's also worth noting that the majority (67%) of the heat from
combustion ( which determines the temperature of the plug, and thus
the temperature at the tip of the central electrode ) arrives
via the metal body of the plug - predominately from the bottom
surfaces and the inside of the threaded area, and the exposed
insulator only transfers 20% of the heat to the plug, and the
exposed central electrode only 4%, and the exposed earthed electrode
transfers 8%. The temperature range of a plug arises from the
sum total of the heat flows within the plug, which determine the
temperature of tip of the central electrode and (less importantly),
the earthed electrode, not the ceramic - as originally claimed
by altavoz.

I previously wrote:-
>The heat range is defined by the length and diameter of the
>special conductive seal in the body of the plug and the position
>of that seal relative to the electrode tip. If the electrode provides
>a long path to reach the heat transfer region, then the plug
>is "hot", and if the path is short then the plug is "cold".
>                    Cold              Medium             Hot
>  4% dissipated     |oxo|             |oxo|             |oxo|
>                   _|oxo|_           _|oxo|_           _|oxo|_
>                __/ |oxo| \__     __/ |oxo| \__     __/ |oxo| \__
>               |   /ooxoo\   |   |   /ooxoo\   |   |   /ooxoo\   |
>    body       |  /oooxooo\  |   |  /oooxooo\  |   |  /oooxooo\  |
>10% dissipated  | |oooxooo| |     | |oooxooo| |     | |oooxooo| |
>                | |oooxooo| |     | |oooxooo| |     | |oooxooo| |
>                | |oooxooo| |     | |oooxooo| |     | |oooxooo| |
>                |_ \ooxoo/ _|     |_ \ooxoo/ _|     |_ \ooxoo/ _|
> heat transfer    ||ooxoo||         ||ooxoo||         ||ooxoo||
> region  64%     <||ooxoo||>       <||ooxoo||>       <||ooxoo||>
>  dissipated     <||ooxoo||>       <||ooxoo||>       <\|ooxoo|/>
>                 <||ooxoo||>       <\|ooxoo|/>       <| |oxo| |>
> gas seal        <\|ooxoo|/>       <| |oxo| |>       <| |oxo| |>
>                 <| |oxo| |>       <| |oxo| |>       <| |oxo| |>
> insulator nose  <| |oxo| |>       <| |oxo| |>       <| |oxo| |>
> 20% dissipated  <|  \x/  |>       <|  \x/  |>       <|  \x/  |>
>                 <|   x   |>       <|   x   |>       <|   x   |>

       Bruce Hamilton

From: John De Armond
Newsgroups: rec.outdoors.rv-travel,alt.rv
Subject: Re: 460 Manifold Bolt problem
Date: Sun, 18 Nov 2007 21:51:08 -0500
Message-ID: <>

On Sun, 18 Nov 2007 22:51:29 GMT, "Steve R." <> wrote:

>A side note- book says plugs every 30k, the odo reads 37k and the plugs look
>good, are Autolite Platinums but since I'm in this far...

Hi Steve.  I'd leave those plugs alone.  With modern fuel and EFI, plugs are good for
the life of the engine in most cases, the exception being an engine that's an oil
user.  I quit changing plugs a couple of decades ago.  140k miles on a Toyota with
the original plugs.  120k on my 94 Caprice with original plugs.  100k on the Ford
Aerostar van that I'm driving now.

The downside to changing plugs is that there is some minor risk of either damaging a
plug hole or getting a bad plug.  I learned the latter lesson back in my racing days.
An old mechanic's adage is "Never start a race on a new plug", referring to single
cylinder engines, of course.  I've had new out of the box plugs within minutes of
installation, crack an insulator, lose a side electrode or just turn up bad for no
reason that I could discern.  One of the more boring tasks I had to do as a race
mechanic was to "burn in" enough plugs for each race.  That involved running them,
usually in a dyno mounted engine, for a few minutes to break 'em in and cull the bad

If it were my engine I'd leave well enough alone.


From: Dave Baker
Subject: Re: Proper Way to Gap Spark Plugs?
Date: Tue, 8 Nov 2005 03:23:20 -0000
Message-ID: <43701a2a$0$41148$>

Julie P. <> wrote in message
> Everytime I change my spark plugs, I have a hard time gapping them. I
> use the round disc-type gapper (size of a half dollar coin) so I can
> adjust the gap to the exact size I need, the kind you can get a most
> auto parts store for $0.99 or so.
> By hooking the grounding prong (is that what it's called?) of the spark
> plug over the hole in the spark plug gapper, I can get the prong to move
> away from the other prong (similar to opening a bottle cap), as the
> gapper gives me the leverage to do this. But it always bends too far
> away. And getting the prong to move back in is a pain. I usually end up
> trying to press the prong against a hard flat surfaced to bend it in. It
> takes me about an hour or more to gap just four plugs!
> Is there an easier way?  Thanks,

Struth, an hour? It should take about a minute per plug. I don't normally
use any special tools, just a watchmakers screwdriver to open the gap if
necessary (only on copper electrode plugs NOT the thin platinum ones) and
feeler gauges to set and measure it. To close the gap just insert the
required thickness of feeler gauges, hold the plug upside down and tap the
earth electrode gently on a heavy, solid piece of clean metal (steel plate,
old cylinder head, the top of a vice etc) until the feeler gauge is a nice
sliding fit.

To open the gap if it starts off too small.

1) With copper electrodes you can insert a watchmakers screwdriver and
gently lever the electrodes apart a bit making sure not to apply any side
force and break the insulator.

2) With platinum electrodes you'll need the hook tool because the platinum
electrode is too thin to lever against.

Always set your gap by starting off too big and tapping the earth electrode
back down to size. If you bugger about with the hook tool trying to bend the
earth electrode to an exact gap you'll be there for ever - which clearly is
where you're at right now. You're always fighting the spring in the material
when you try to bend metal to an exact size. However, by tapping gently you
can achieve a very precise control over how much the gap alters per tap.
Similarly, never try to just press the gap down to size by pushing the plug
against a vice. That's just applying a bending force but by another method.
It requires a sharp, but light, impact to obtain control over the material
Dave Baker

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