Basic auto ignition electric Q

[Paul Conners]

Single coil, rotor & distributor cap system, 4 cylinder.

Is the coil housing grounded? I always thought the coil housing was the
return path for the secondary circuit / spark current. I know that the
primary circuit doesn't use ground in the coil: it is grounded through the
ignition points in the distributor (this is a 70's vintage car).

Both the original and replacement coils do not show any continuity (lo res.
or high res) at all to the HV output connector.

Is the return path for the secondary circuit / HV spark through the points?
Or...?

Thanks.

 

[Ashton Crusher]

On Sun, 18 Oct 2009 21:00:08 -0700, Paul Conners
<pconners98@gUSmail.com> wrote:

Single coil, rotor & distributor cap system, 4 cylinder.

Is the coil housing grounded? I always thought the coil housing was the
return path for the secondary circuit / spark current. I know that the
primary circuit doesn't use ground in the coil: it is grounded through the
ignition points in the distributor (this is a 70's vintage car).

Both the original and replacement coils do not show any continuity (lo res.
or high res) at all to the HV output connector.

Is the return path for the secondary circuit / HV spark through the points?
Or...?

Thanks.

I don't think the housing is grounded.

 

[Steve N.]

"Paul Conners" <pconners98@gUSmail.com> wrote in message
news:0001HW.C7013258010FE9ACB08A39AF@news.eternal-september.org...

Single coil, rotor & distributor cap system, 4 cylinder.

Is the coil housing grounded? I always thought the coil housing was the
return path for the secondary circuit / spark current. I know that the
primary circuit doesn't use ground in the coil: it is grounded through the
ignition points in the distributor (this is a 70's vintage car).

Both the original and replacement coils do not show any continuity (lo
res.
or high res) at all to the HV output connector.

Is the return path for the secondary circuit / HV spark through the
points?
Or...?

The primary & the secondary share a common grounding point thru a grounding
wire and capacitor to ground. The coil actually fires when the points open
and the electromagnetic field collapses and induces a large voltage into the
secondary. So, the secondary is not grounding thru the points. There's a
ground wire from the neg. primary post, thru a capacitor (which passes AC
current which is how the coil works. It's like a step-up transformer) to
engine ground.

http://users.mrbean.net.au/~rover/ketterin.htm

http://www.international-auto.com/fiat-lancia-electrical-system/how-to-test-an-ignition-coil.cfm

 

[Don Stauffer]

terryS wrote:

No computers then. If not 'What's a computer it was some form of
'calculator' such as a circular slide rule or something!
Cheers.

Computers then were folks who sat down at adding machines or desk
calculators (mechanical devices that not only added and subtracted, but
could multiply) and ran long series of computations. This terminology
carried into the early fifties, then disappeared.

Actually, with some ignitions of the Kettering type (coil and breaker
points) the vacuum lines had both advance and retard functions, and
could be considered almost a "fluidic" computer. Much more involved was
the fully evolved fluidic computing going on inside a carburetor in the
sixties and later. Marvels of non-electronic computing.

 

[hls]

"Steve N." <snewman24@cox.net> wrote in message
news:SdWCm.31895$yM3.14302@newsfe05.iad...

"Paul Conners" <pconners98@gUSmail.com> wrote in message
news:0001HW.C7013258010FE9ACB08A39AF@news.eternal-september.org...
Single coil, rotor & distributor cap system, 4 cylinder.

Is the coil housing grounded? I always thought the coil housing was the
return path for the secondary circuit / spark current. I know that the
primary circuit doesn't use ground in the coil: it is grounded through
the
ignition points in the distributor (this is a 70's vintage car).

Both the original and replacement coils do not show any continuity (lo
res.
or high res) at all to the HV output connector.

Is the return path for the secondary circuit / HV spark through the
points?
Or...?

The primary & the secondary share a common grounding point thru a
grounding wire and capacitor to ground. The coil actually fires when the
points open and the electromagnetic field collapses and induces a large
voltage into the secondary. So, the secondary is not grounding thru the
points. There's a ground wire from the neg. primary post, thru a capacitor
(which passes AC current which is how the coil works. It's like a step-up
transformer) to engine ground.

Right. The secondary voltage relies on a ringing (AC) voltage which is
generated
by the collapse of the magnetic field, inducing currennt via a series tuned
circuit, IIRC.

 

[terryS]

On Oct 19, 7:23 am, "Steve N." <snewma...@cox.net> wrote:

"Paul Conners" <pconner...@gUSmail.com> wrote in message

news:0001HW.C7013258010FE9ACB08A39AF@news.eternal-september.org...

Single coil, rotor & distributor cap system, 4 cylinder.

Is the coil housing grounded? I always thought the coil housing was the
return path for the secondary circuit / spark current. I know that the
primary circuit doesn't use ground in the coil: it is grounded through the
ignition points in the distributor (this is a 70's vintage car).

Both the original and replacement coils do not show any continuity (lo
res.
or high res) at all to the HV output connector.

Is the return path for the secondary circuit / HV spark through the
points?
Or...?

The primary & the secondary share a common grounding point thru a grounding
wire and capacitor to ground. The coil actually fires when the points open
and the electromagnetic field collapses and induces a large voltage into the
secondary. So, the secondary is not grounding thru the points. There's a
ground wire from the neg. primary post, thru a capacitor (which passes AC
current which is how the coil works. It's like a step-up transformer) to
engine ground.

http://users.mrbean.net.au/~rover/ketterin.htm

http://www.international-auto.com/fiat-lancia-electrical-system/how-t...

'Old type' systems. IIRC the 'points' were between the coil primary
and ground! In other words, in operation, the points completed the
negative side of the circuit. With ignition 'on' (again IIRC) 12 volts
etc. was connected to the hot end of the coil's primary.
The points opened (or closed, can't remember which!) the magnetic
field either collapsed or or rose (can't remember which!) and the
secondary made a bl**dy big spark that was distributed by the rotor to
the appropriate spark plug!
Very simple system! If the 'points' got bad take them out and rub them
on stone/rock to smooth them up and then a week or so later replace
them or dress them up with a file! If the capacitor (condenser) went
bad you could sometimes use an old radio capacitor instead hanging it
below the distributor with wire!
No computers then. If not 'What's a computer it was some form of
'calculator' such as a circular slide rule or something!
Cheers.

 

[Paul Conners]

The primary & the secondary share a common grounding point thru a grounding
wire and capacitor to ground. The coil actually fires when the points open
and the electromagnetic field collapses and induces a large voltage into the
secondary. So, the secondary is not grounding thru the points. There's a
ground wire from the neg. primary post, thru a capacitor (which passes AC
current which is how the coil works. It's like a step-up transformer) to
engine ground.

In order to test the coil in place (without a point set), there must be a
capacitor from coil (-) to ground, yes? And then ground the (-) terminal and
release. Spark should be seen?

Thanks.

 

[hls]

"Paul Conners" <pconners98@gUSmail.com> wrote in message
news:0001HW.C701D7E50136B6BEB08A39AF@news.eternal-september.org...

The primary & the secondary share a common grounding point thru a
grounding
wire and capacitor to ground. The coil actually fires when the points
open
and the electromagnetic field collapses and induces a large voltage into
the
secondary. So, the secondary is not grounding thru the points. There's a
ground wire from the neg. primary post, thru a capacitor (which passes AC
current which is how the coil works. It's like a step-up transformer) to
engine ground.

In order to test the coil in place (without a point set), there must be a
capacitor from coil (-) to ground, yes? And then ground the (-) terminal
and
release. Spark should be seen?

Thanks.

There will be already be a capacitor, usually inside the distributor, or
maybe
external to it. You should be sure that capacitor is good before you make
any
judgements on such a test.

Then when you ground the (-) terminal, the primary coil will charge, and
when you release the ground the field will decay and you should get a spark
from the HV tower of the coil to ground.

 

[Paul Conners]

There will be already be a capacitor, usually inside the distributor, or
maybr external to it. You should be sure that capacitor is good before you
make
any judgements on such a test.

What is the value of such a cap, uF & V?

Then when you ground the (-) terminal, the primary coil will charge, and
when you release the ground the field will decay and you should get a spark
from the HV tower of the coil to ground.

Thanks.

 

[Steve W.]

Paul Conners wrote:

Single coil, rotor & distributor cap system, 4 cylinder.

Is the coil housing grounded? I always thought the coil housing was the
return path for the secondary circuit / spark current. I know that the
primary circuit doesn't use ground in the coil: it is grounded through the
ignition points in the distributor (this is a 70's vintage car).

Both the original and replacement coils do not show any continuity (lo res.
or high res) at all to the HV output connector.

Is the return path for the secondary circuit / HV spark through the points?
Or...?

Thanks.

Both windings in the coil ground through the negative terminal.

You should find conductivity from the + terminal to the - Terminal. And
from the high voltage terminal to the - terminal.

The positive terminal on the coil goes to the battery (through a switch
or relay usually) On most vehicles this voltage is NOT 12 volts, it is
stepped down through the ballast resistor or through resistance wire so
that 6 volts gets to the coil.

The - side gets connected to the points. You will usually see a
capacitor on the coil, it is there to stop radio noise and voltage
spikes from going into the wiring.
On the points you will see another one. It's purpose is to damp the
electric pulse and keep the points from arcing.

This all supposes the old style can coils.
Most of the new high voltage coils DO ground through the coil frame.

--
Steve W.

 

[hls]

"Paul Conners" <pconners98@gUSmail.com> wrote in message
news:0001HW.C701F660013DDB5CB08A39AF@news.eternal-september.org...

There will be already be a capacitor, usually inside the distributor, or
maybr external to it. You should be sure that capacitor is good before
you
make
any judgements on such a test.

What is the value of such a cap, uF & V?

They vary. Typically they are between .15 and .25 microFarads.
I know that these capacitors are subjected to test voltages up to about
1800 volts.

I have heard this discussed, but dont know the exact working voltage of
the units... A figure of 600 WV has been quoted, but I dont honestly know.

If I were going to run this test (if I were having a problem), I would buy
a new ignition capacitor from the FLAPS and use it. I would replace the
old one whatever the case.

 

[Scott Dorsey]

hls <hls@nospam.nix> wrote:

"Paul Conners" <pconners98@gUSmail.com> wrote in message
news:0001HW.C701F660013DDB5CB08A39AF@news.eternal-september.org...
There will be already be a capacitor, usually inside the distributor, or
maybr external to it. You should be sure that capacitor is good before
you
make
any judgements on such a test.

What is the value of such a cap, uF & V?

They vary. Typically they are between .15 and .25 microFarads.
I know that these capacitors are subjected to test voltages up to about
1800 volts.

Yes. Originally they were foil capacitors made with oiled paper, but
these days most of them are made with thick mylar film.

I have heard this discussed, but dont know the exact working voltage of
the units... A figure of 600 WV has been quoted, but I dont honestly know.

Probably a lot higher than that today, because these days they use much
thicker mylar film with metallization, rather than wrapping film with
foil. The metallized film technology is much cheaper, and they tend to
use much thicker material than necessary in order to make the caps look
and feel like the old ones. This means higher breakdown voltages.

If I were going to run this test (if I were having a problem), I would buy
a new ignition capacitor from the FLAPS and use it. I would replace the
old one whatever the case.

These days, condensers hardly ever fail. They'd probably last the life
of the engine. In the paper and oil days, you had to replace them all
the time because they would degrade pretty quickly. The thing is, you
get a free condenser every time you get new points so you might as well
just replace it.

Or install a Mark V capacitive discharge ignition module and then you'll
never have to change your condenser OR points ever.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

 

[hls]

"Scott Dorsey" <kludge@panix.com> wrote in message
news:hbiqgs$6f$1@panix2.panix.com...

hls <hls@nospam.nix> wrote:
"Paul Conners" <pconners98@gUSmail.com> wrote in message
news:0001HW.C701F660013DDB5CB08A39AF@news.eternal-september.org...
There will be already be a capacitor, usually inside the distributor,
or
maybr external to it. You should be sure that capacitor is good before
you
make
any judgements on such a test.

What is the value of such a cap, uF & V?

They vary. Typically they are between .15 and .25 microFarads.
I know that these capacitors are subjected to test voltages up to about
1800 volts.

Yes. Originally they were foil capacitors made with oiled paper, but
these days most of them are made with thick mylar film.

I have heard this discussed, but dont know the exact working voltage of
the units... A figure of 600 WV has been quoted, but I dont honestly know.

Probably a lot higher than that today, because these days they use much
thicker mylar film with metallization, rather than wrapping film with
foil. The metallized film technology is much cheaper, and they tend to
use much thicker material than necessary in order to make the caps look
and feel like the old ones. This means higher breakdown voltages.

If I were going to run this test (if I were having a problem), I would buy
a new ignition capacitor from the FLAPS and use it. I would replace the
old one whatever the case.

These days, condensers hardly ever fail. They'd probably last the life
of the engine. In the paper and oil days, you had to replace them all
the time because they would degrade pretty quickly. The thing is, you
get a free condenser every time you get new points so you might as well
just replace it.

Or install a Mark V capacitive discharge ignition module and then you'll
never have to change your condenser OR points ever.
--scott

Condensors seldom failed even in the old days, but occasionally they
did. A person would have been a fool to pull a wrench on one of
those Kettering systems and not replace the condensor along with the
points.

I have, once, seen a bad set of points. Fresh factory new. Shorted
always.

Saludos cordiales

 

[hls]

"Jamie" <jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote in message

Hope that did something fer ya!


That is a pretty good summary, Jamie.

 

[Jamie]

Paul Conners wrote:

Single coil, rotor & distributor cap system, 4 cylinder.

Is the coil housing grounded? I always thought the coil housing was the
return path for the secondary circuit / spark current. I know that the
primary circuit doesn't use ground in the coil: it is grounded through the
ignition points in the distributor (this is a 70's vintage car).

Both the original and replacement coils do not show any continuity (lo res.
or high res) at all to the HV output connector.

Is the return path for the secondary circuit / HV spark through the points?
Or...?

Thanks.

The shell of the coil plays no part of the process..

The (+) terminal is connected to the power source in your
car some where. Normally a ballast resistor is used to reduce
power in run state and use full power while starting.. This
is due to battery voltage being dropped when the starter is
engaged.

The (-) of the coil is connected to the points, which also
has a condenser/capacitor of a value normally in the range of
.047, But that varies depending on the coil that is being used.

When the points are closed, the coil will approach saturation.
It is important to insure you have sufficient closure time on the
points to cover for higher RPM's, (DWELL time) is important to make
sure you have enough time to allow the coil to reach saturation at
the highest RPM's

Some problems existed when the cam lobs wore out and it was hard
to get the dell time correct with enough opening time on the points
along with a bad set of bearings in the distributor.

When the points open, the capacitor(condenser) will act as a
temporary shorting post. This will dampen the arch that otherwise
would be at the points on open and thus, destroy them over time.

Also, the capacitor acts as a path to ground for that moment and
then quickly gets charged there for releasing the current that is
present in the coil. This is called collapsing the inductor (coil).

When collapsing of the field takes place, the energy then gets
released from the coil is a reverse polarity. AT this point, the
capacitor (condenser) will act as its path to ground which will be
near 0 ohms and because there is virtually nothing loading the coil
down, all of the energy that it took, in the time given to saturate
the coil (Dwell), gets released all at once, which multiplies the
voltage many times over on top of the coil already having a step up
design internally to the plug wire..

Then the cycle starts all over again when the points close, at which
time, the only current the points see is the capacitor (condenser)
charge, which gets discharged of course, via the points.

Which stands the reason why if you have a bad condenser, you'll have
arching which burns the points and does not allow a good path to ground
to give you full potential to the HV wire.
Of course, if the condenser is shorted, your car just won't start at
all.! no spit or sputter!.

Hope that did something fer ya!

 

[Tegger]

"hls" <hls@nospam.nix> wrote in
news:qsednY6j6dlxZUHXnZ2dnUVZ_vmdnZ2d@giganews.com:

Condensors seldom failed even in the old days, but occasionally they
did. A person would have been a fool to pull a wrench on one of
those Kettering systems and not replace the condensor along with the
points.

I remember that condensers were so cheap there was no point in tempting
fate by leaving the old one in when you replaced the (also cheap) points.


--
Tegger

 

[Paul Conners]

They vary. Typically they are between .15 and .25 microFarads.
I know that these capacitors are subjected to test voltages up to about
1800 volts.

I have heard this discussed, but dont know the exact working voltage of
the units... A figure of 600 WV has been quoted, but I dont honestly know.

If I were going to run this test (if I were having a problem), I would buy
a new ignition capacitor from the FLAPS and use it. I would replace the
old one whatever the case.

The reason I ask is that there is none in this system. A friend has purchased
a solid-state magnetic-triggered ignition module that replaces the point set.
A trigger sleeve slips over the distributer cam lobes and contains 4 small
magnets.

It is new and I can't get it to work -- no spark. My next step in
troubleshooting is to test the coil, but sans capacitor, I guess it can't be
done. I guess I'll buy a cap just to test the coil.

BTW, I do get 11K secondary resistance and low (I forget the exact value)
primary resistance referenced to the (-) terminal.

Thanks to all for your help.

 

[Steve W.]

Paul Conners wrote:

They vary. Typically they are between .15 and .25 microFarads.
I know that these capacitors are subjected to test voltages up to about
1800 volts.

I have heard this discussed, but dont know the exact working voltage of
the units... A figure of 600 WV has been quoted, but I dont honestly know.

If I were going to run this test (if I were having a problem), I would buy
a new ignition capacitor from the FLAPS and use it. I would replace the
old one whatever the case.

The reason I ask is that there is none in this system. A friend has purchased
a solid-state magnetic-triggered ignition module that replaces the point set.
A trigger sleeve slips over the distributer cam lobes and contains 4 small
magnets.

It is new and I can't get it to work -- no spark.

OK if this is a points equipped vehicle you will probably need to run a
direct battery feed for the new system. Many of the old systems used a
resister in line (either a simple ballast resister or actual resister
wire) to drop the voltage at the points to 6 volts or so. Made the
points last longer. However a 12 volt ignition will not like the voltage
that low (GM HEI unit won't even fire under 9 volts).

If it's a Ford or Chrysler it uses a separate ballast resistor. Just
bypass that. If it's a GM the wire feeding the coil positive will need
to be replaced.


My next step in

troubleshooting is to test the coil, but sans capacitor, I guess it can't be
done.

Sure it can. Take a spark plug. Install ONE wire to connect it to the coil.

Now take a strand of copper wire and wrap it around the plug base. Now
connect the other end to the neg. terminal on the coil. Now take a feed
line from the battery with pos and neg. Connect the positive side to the
coil. Take the negative side and touch it to the negative terminal a
second or so. Pull it away FAST. You should see a spark if the coil is OK.


I guess I'll buy a cap just to test the coil.

BTW, I do get 11K secondary resistance and low (I forget the exact value)
primary resistance referenced to the (-) terminal.

Thanks to all for your help.

--
Steve W.

 

[bw]

"Paul Conners" <pconners98@gUSmail.com> wrote in message
news:0001HW.C701F660013DDB5CB08A39AF@news.eternal-september.org...

There will be already be a capacitor, usually inside the distributor, or
maybr external to it. You should be sure that capacitor is good before
you
make
any judgements on such a test.

What is the value of such a cap, uF & V?

Older caps, such as those in buzz coils were 0.47 uF and 400 volts
Ford model T caps were supposed to be about the same. See a Dyke's manual.
Most automotive caps were 0.22 uF and 400 volts AC or 600 volts AC
Briggs and Stratton magnetos used the same rating forever. 0.22 uF and 400
volts
Some caps have other values, such as 0.15 uF, but 0.22 will be the most
common by far and will work in just about anything. The only real variable
is the type of mount, how long the center wire extends, and if you want a
connector at the end of the wire.

Then when you ground the (-) terminal, the primary coil will charge, and
when you release the ground the field will decay and you should get a
spark
from the HV tower of the coil to ground.

 

[Mike Cook]

Older caps, such as those in buzz coils were 0.47 uF and 400 volts
Ford model T caps were supposed to be about the same. See a Dyke's manual.
Most automotive caps were 0.22 uF and 400 volts AC or 600 volts AC
Briggs and Stratton magnetos used the same rating forever. 0.22 uF and 400
volts
Some caps have other values, such as 0.15 uF, but 0.22 will be the most
common by far and will work in just about anything. The only real variable
is the type of mount, how long the center wire extends, and if you want a
connector at the end of the wire.

What flavor are these caps (or what modern equivalent)? Non-polar
electrolytic? Poly-something?