Date: Fri, 11 Jun 2004 16:50:46 -0800
Reply-To: Mark Tuovinen <mst@AK.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Mark Tuovinen <mst@AK.NET>
Subject: Re: vanagon Digest - 11 Jun 2004 - Special issue (#2004-549)
Content-type: text/plain; charset=us-ascii
Don,
Indexing spark plugs is not about changing the angle of entry. It is done to ensure that the electrodes are aimed to put the spark in the same spot in all cylinders. By having the electrodes aimed correctly in the combustion chamber you will get equal power from each cylinder, so the theory goes anyway, I have never seen data to confirm or deny this, though it does make sense. Because not all spark plugs will have the electrode pointing in the correct direction once they are installed, shims are used to adjust their position. If the plug was a quarter turn off you might add one shim which makes the threaded portion of the plug sit higher in the head and and the electrode stop in the proper position. I have also seen an automobile manufacturer index plugs on cars in an attempt to squeeze extra fuel economy out of them.
Mark in AK
----- Original Message -----
From: don spence <dspence@OANET.COM>
Date: Friday, June 11, 2004 3:56 pm
Subject: Re: vanagon Digest - 11 Jun 2004 - Special issue (#2004-549)
> Uh Bruce, no offence but I think you've been taken by an urban myth.
> The angle of the plugs entry into the combustion chamber is controlled
> by the angle of the spark plug hole or port. Any lop-sided shim/washer
> would only effect the seal at the base of the plug. I can't
> imagine a
> washer that could overpower and reorient a plug bore. If you want to
> change the angle you'd have to drill and tap the holes where you want
> them. yes? No?
> On Friday, June 11, 2004, at 03:28 PM, Automatic digest processor
> wrote:
>
> > Any of you hot rodders out there remember the indexing washers for
> > sparkplugs? These were essentially shims that you would use to "aim"
> > your
> > spark plug when installing your plugs in the head. When torqued, if
> > your
> > plug wasn't at the optimum angle (spark not facing the most
> turbulent> fuel/air mixture), you pulled the plug out threw in one
> or two more
> > indexing
> > washers and the angle of the plug could be aimed to optimize
> burn for
> > most
> > power (they weren't worried about emissions in those days, but a
> > better burn
> > is cleaner in this case).
>
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