To add even more trivia to a beat =
to death
subject:
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.
Personal experience: Don't get you =
hand
anywhere near the business side of one of these (coil output). =
Not
only does the module decide when to fire the coil, it gives it a =
sustained
spark. It hurts lots more than when you get hit by =
points. I ran
one in a beetle that I circle track raced for years and it =
brought
home more than one trophe. It later went into a '73 bus and =
ran
fine. In case it matters, I also carried a set of points and a =
condenser in the bus just in case.
Mark Rokus
'87 Syncro =
(wifie's)
'87
Syncro Westy: Mine :-)
'81 Westy
'82 Diesel =
Rabbit
'72
Karmann Ghia
----- Original Message ----- =
Sent: Saturday, May 13, =
2000 10:54
PM
Subject: dwell
Yes dwell
angle is still a factor in transistorized =
ignitions.
It is no longer adjustable but through software it is possible =
in
distributorless ignitions, but no the service =
tech
cannot do so.
Dwell
is expressed in degrees of distributor shaft
rotation. 30*dwell on an eight cylinder engine =
would
leave 120* of cumulative rotation for the coil =
to be off charge and therefore cooling somewhat. 45* on a =
four
cylinder engine would leave 180* to cool, and 180* =
to charge
the coil cumulatively. Simply because the distributor shaft =
rotates
360* of course. If you have a transistorized ignition, =
breakerless
whatever, you can still measure the dwell angle. If =
the
system is weak chances are you will find a shorter =
dwell
angle when you test it. I have done this and I know it
works. In fact, transistorized ignitions can and do =
have
variable dwell periods factored into the circuitry =
on
some applications. In reality the hall effect sensor is =
simply a
switch and not the conductor that all current must =
pass to
charge the coil and this leaves you many =
possibilities.
To
understand this best it is best to realize that dwell exists =
even in
distributorless ignitions, though it is often =
ignored, it
is a percentage of time in a given engine =
revolution.
That doesn't matter but that it is important to realize =
that
without contact points you do still have a dwell
angle.