Re: IML: 56 Ignition Problem

[Brad Weikert <a292@xxxxxxx>]

Another thought for you, you say that while the engine is running you 
are getting the full 12 volts to the ignition system.  It would not 
surprise me if that's what your volt meter is telling you even though 
it's not really so.  Here's why.  With the engine running obviously the 
points are rapidly opening and closing.  When the points are open there 
will be battery voltage at the coil but when the points close the 
voltage will drop.  Your volt meter cannot respond so quickly to show 
the voltage fluctuation so instead will hover near the voltage peak 
from the open points portion of the cycle.

I'm thinking that you may very well have a bad condenser.  If you are 
getting a weak spark and the points are getting rapidly burnt I would 
first check the condenser as that would cause both of these symptoms.  
If you have an analog ohmmeter you can sometimes check to see if the 
condenser is working although you cannot check if it has the correct 
value.  Remove the condenser from the car and connect the ohmmeter 
leads to the condenser.  The needle should jump up and then rapidly 
return to infinite resistance.  Now reverse the leads and the meter 
should react the same way again.  This is not a foolproof way of 
checking but will at least tell you if it's acting like a capacitor, 
which is all a condenser is.  If the meter has a steady reading of 
anything other than infinite the condenser is leaking voltage.  If the 
meter doesn't briefly jump up the condenser is probable open and acting 
as if it's not even there.

Have a good day
Brad


On Feb 5, 2007, at 9:39 AM, Brad Weikert wrote:

> Check the voltage with the points closed.  With the points open no 
> current is flowing through the coil and therefore there will be 12 
> volts to the coil and points regardless of how much resistance the 
> ballast has.  The voltage drop will only take place while current is 
> flowing through the resistor.  With the points closed check the 
> voltage at the positive terminal of the coil to see what the actual 
> voltage drop is.
>
> A bad condenser would also cause a weak spark and excessive arcing on 
> the points, drastically reducing their life.
>
> Brad
>
>
> On Feb 5, 2007, at 8:19 AM, Jeff Cantor wrote:
>
> > I've determined that the primary cause of my poor performance 
> > recently is burnt points and a dyeing coil.  Some investigating has 
> > lead me to believe that the route cause of these problems is that, 
> > while running, the ignition system is getting the full battery 
> > voltage of 12V rather than the 6-8V that is is designed for.  My 
> > question for the group is where to go to correct this problem.
> >
> > The first and most obvious culprit would be the coil or ballast 
> > resistor but both the original one and a replacement I installed 
> > appear to have approximately the correct resistance and produce the 
> > same result (12V across the open points when the key is in the one 
> > position).  This leads me to believe that whatever part of the system 
> > that is supposed to switch between providing 12V when starting and 
> > 6-8V when running is not making that transition correctly.  But what 
> > part is that?  Based on the wiring diagram in the FSM, it looks like 
> > power to the coil resistor goes through both the starter and horn 
> > relays as well as the ignition switch.  Which one of these makes the 
> > transition?
> >
> > Thanks,
> > Jeff
> > '56 Sedan
> > Trenton, NJ



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