When a distributor cam goes around it opens and closes a set of points.
Dwell is the expression of how much time the points are closed, expressed
in degrees of rotation of the crankshaft.
Points need to be closed for enough time to build up the magnetic field
in the coil so that when it colapses (points open) a large enough voltage
spike is generated, which is routed to the spark plugs.
Not enough dwell produces a weak spark. Too much dwell overheats the
ignition coil.
Peace,
Pat
- Support Habitat for Humanity, A "hand up", not a "hand out" -
Pat Horne, Network Manager, Shop Supervisor, Future planner
CS Dept, University of Texas, Austin, Tx. 78712 USA
voice (512)471-9730, fax (512)471-8885, horne@cs.utexas.edu
On Tue, 10 Jul 2001, Daniel Neuman wrote:
> All right so.. I can't adjust the 'dwell' of the pertronix and I realize that
> I don't exactly know what dwell is. Oh well... I don't have a problem with
> the Pertronix unit. I think it works great and I will never ever go back to
> points. The only problem I had was somehow the wires got caught on the rotor
> and spun up and ripped off. But I bought a spare off of ross and I should be
> good to go.
> Daniel 69 2000
> SF CA
>
> > Hi Daniel,
> >
> > Nice idea but I'm not sure that would work. Aren't there magnets embedded
> > in the Pertronix that sense the rotational position of the center cam, for
> > firing purposes. Changing to an offset for the mounting plate will simply
> > alter the rotational position, which is the same effect as adjusting the
> > timing (rotating the distributor as a whole). The standard ignition points
> > are more mechanical in nature, where the offset of the mounting plate
> > changes the interval of time that the points are opened before they close.
> >
> > Probably the best place to experiment is in the electronics areas,
> > particularly the coil. Some people tell me the Pertronix works great with a
> > hotter coil. Good luck, I'm looking forward to hearing of successes with
> > these units.
> >
> > Fred - So.SF
> >
> > ______________________ Reply Separator ________________________
> > >Subject: Pertronix Debate
> > >Author: Daniel Neuman <dneuman@quark.sfsu.edu>
> > >Date: 7/10/2001 1:48 PM
> > >
> > >Hello All,
> > >I have a 'spare' pertronix unit that I want to try to jigger to see if
> > >I can make it work a bit better. I know that Fred Katz does not like
> > >them because you can not adjust the dwell. The two mounting screws do
> > >not allow for any adjsutment of when it 'fires' I want to circularly
> > >ovalize these two mounting screws so that the unit can be slightly
> > >rotated back and forth for some dwell adjsutment. Does anybody have
> > >any ideas about the usefullness of this excercise?
> > >Because of the MSD ignition I can't actually check the swell with a
> > >meter so I guess I am just going to tweak the plate one way or the
> > >other and see if it makes any difference...can't really afford a bunch
> > >of dyno runs ya know..
> > >Daniel 69 2000
> > >SF CA
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