Yes, you are right, because as the rotor tip is passing the stud on the cap,
which probably takes about 3 degrees of rotation, since the rotor tip is
and the flatted portion of the stud is somewhat wide too, the spark occurs
SOMEWHERE WITHIN this time period,
governed by the instant the window in the rotating metal cup on the
distributor shaft begins to pass the
Hall Effect Sensor. This turns off the voltage to the coil, and the
collapsing magnetic field inside the coil causes the spark pulse.
Does that sound right?
Tom of the overheated engine.
You understand it very well.
it is either the low to high transition or the high to low transition of
the shutter vane passing the hall effect that signals the ignition
control module to break current flow thru the coil primary circuit
causing the magnetic field to collapse which induces a high voltage in
the ignition coil secondary.
The distributor cap and rotor have nothing to do with ignition timing.
you are an idiot.
if you move the distributor cap 15 degrees, the timing wiill be out 15
degrees. to say that the cap and rotor have no effect on timing makes as
much sense as you saying man can fly if he flaps his arms like a bird and
jumps off a bridge.
There are 2 distinct sections to a distributor-
The low voltage section which is below the cap and rotor. This section
controls the spark timing, either by using points (remember them?)
or a Hall Effect Sensor or similar electronic device, to open the coil
circuit and provide the spark pulse, to spark the plug.
By turning the distributor relative to the engine block, this changes the
timing of when the spark occurs relative to the piston position.
The high voltage section is composed of the cap and rotor, and is like a
large selector switch
. The spark pulse comes in through the center post on the cap and through
the rotor via the springy finger on it. The tip of the rotor then sends the
spark to one of the plug wire towers that it is nearest to, and then down
that plug wire to the spark plug. The rotor tip is wide and the tower post
is too, so there is about a 5 degree interval during which they are close
enough to send a spark across them. Within that
relatively wide interval, the lower portion triggers off the spark at an
exact time to make the engine run right.
The distributor cap and rotor could be run off a different shaft than the
points/hall sensor stuff, and the engine would still run the same.
It is only out of convenience that they are both driven by the same shaft.
Somewhere in history there probably was a car that ran them separately.
TheModel T Ford had 4 separate coils, each connected to a spark plug, and
its "distributor" (I think it had a different name though), turned the low
voltage of each coil on to fire the plug.
Nobody here is an idiot. This stuff can be confusing as hell.
Tom the hot engine guy
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