I got over a hundred thou out of one set of them.  The center electrode was
eroded to a kinda triangular shaped nubbin, but they still were firing just
fine.

My understanding is that, as one electrode gets hot, its resistance
increases and the spark then shunts over to a different one, etc.

Although the gap was pretty big on my 100K plugs, there was no appreciable
wear on the side electrodes.

Karl Wolz

----- Original Message -----
From: "Edward Nutter" <eanutter@POSTOFFICE.PACBELL.NET>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Thursday, May 16, 2002 8:30 AM
Subject: Re: 3 probe plugs

> When I used 'em there was no performance or milage increase. They just
> lasted forEVER.  As near as I could tell, whichever electrode had the
> highest conductance got the spark.  When it wore to where another
> electrode had more conductance, the other got the spark.  That increased
> the effective life of the ground electrode by a factor of 3.  The center
> electrode gradually changed from a circle to a rounded triangle.  As I
> mentioned, that took a long time.
>
> Ed
>
> Jason Willenbrock wrote:
>
> > hey all,
> >
> > what is the benefit, if any, of the bosch 3 electrode spark plugs for
> > vanagons?  better fuel efficiency or what?  and how do you set the
> > gap?  what should the gap be for a 90 vanagon?
> >
> > jason
> >
> > 90gl
> >
>