Hi David,
One of the things that I noticed with my Pertronix is that the output sent
to the coil is not a "one shot" like you would see with points.  (I realize
that there is ringing with points as the field in the coil collapses, but
that's not what I'm talking about). On the Pertronix, once the sensor
detects the magnet, the output oscillates until it no longer sees the
magnet.  If you rotate the engine to the point that the sensor is triggered,
the coil will continue to fire continuously.  Do not try it with the coil
wire connected to the cap or the engine may fire.  I have had it happen.  My
only point is that theoretically you may change the dwell.  I have never had
the need to check it as the nature of the multiple firing of the coil
minimizes the need to adjust the dwell.  (Dwell is set at a certain point to
ensure that the coil saturates properly so that maximum spark will be
generated.)  As a disclaimer, I'll say that this applied to MY unit and may
not be indicative of later designs.  I loved the way mine performed. I loved
that I didn't have to have a point file and business card with me everywhere
I went.  I put it in and forgot about it.  Would buy another in a minute.
Thanks
Mark Rokus
'87 Syncro (wifie's)
'87 Syncro Westy: Mine :-)
'81 Westy
'82 Diesel Rabbit
'72 Karmann Ghia
----- Original Message -----
From: David Beierl <dbeierl@ibm.net>
To: Mark Rokus <marokus@VOYAGER.NET>
Cc: <vanagon@GERRY.VANAGON.COM>
Sent: Sunday, May 14, 2000 10:08 AM
Subject: Re: dwell

> At 23:13 5/13/2000, Mark Rokus wrote:
> >Yes, Pertronix are Hall effect based.  A hall sensor turns on based on
the
> >strength of the magnetic field that they see, thus, it is logical to
> >conclude that you can effect the dwell by changing the distance from the
> >collar (with the magnets in it) and the sensor.  ie... the closer the
> >pick-up is to the collar (magnets) , the longer the sensor will see
> >it.  Obviously, if you get too much of a gap, the pulse will be shorter.
>
> It's logical, but it's not so...decreasing the gap will do nothing (until
> you get physical interference), and decreasing it will perhaps make the
> timing a little late -- or a bit mushy (until the thing stops working at
> all).  But the sensor only provides information to the control module; it
> has no direct effect on the output.  Once the control module knows when
the
> spark is wanted, it generates a pulse without further regard for the
> Hall-effect sensor.
>
> david
> David Beierl - Providence, RI
>   http://pws.prserv.net/synergy/Vanagon/
> '84 Westy "Dutiful Passage"
> '85 GL "Poor Relation"
>
>