EXPLODING COIL !!!!!
Damien D Keffyn
Yet another problem for the 440 powered Plymouth Road
Runner, I was having a lot of problems in the past (if you remember my
postings) with head bolts and exhaust bolts to name a couple, NEW PROBLEM
THE IGNITION COIL JUST EXPLODED!!!!!!!! It was getting warm at first then
after driving for about 20 min it just exploded right there in the traffic!!
WHAT on earth can cause the coil to get so hot that it explodes? It was a
brand new ACCEL HP coil. The specs on the car again are. The Idle was high
at the time when I stopped at the lights and applied the brakes it just
wanted to keep urging forward. Can High Idle cause a problem like this?
thanx
Damien
Nico Over
cause was that the coil (a Jacobs) didn't have the required internal
reistance (approx 1.7 ohm) for a point system so to much current was
generated. I aggravated this problem myself by bypassing the ballast
resistor because of a non-start problem. Bottom line: make sure the
that the coil you put on has the proper internal resistance for the type
of ignition you have. If you don't have the resistance at the coil a
different ballast resistor must be used. Hope this helps. Nico
Mike Allen
ignition, check your ignition module. A high idle should not cause a coil
explosion. Send the remains of your coil back to Accel anyway and tell them
they're lucky you didn't loose an eye, and to keep you from suing for
"severe emotional trauma" plus the wrecker charges, they should send you
another HP Coil absolutely free. Hint- Bosch coils for transistorized
ignition systems are `explosion proof` with a rubber plug to pop out in the
event of a short circuit before an explosion could result. Great
reliability in electronic ignition systems!
-David
>Damien D Keffyn wrote in message <6sm42o$5fu$1...@dalen.get2net.dk>...
Marcus Teague
You should be reading about 7 volts not 12, at the positive side of the coil.
Damien D Keffyn wrote:
> Hi everyone,
> Yet another problem for the 440 powered Plymouth Road
> Runner, I was having a lot of problems in the past (if you remember my
> postings) with head bolts and exhaust bolts to name a couple, NEW PROBLEM
> THE IGNITION COIL JUST EXPLODED!!!!!!!! It was getting warm at first then
> after driving for about 20 min it just exploded right there in the traffic!!
> WHAT on earth can cause the coil to get so hot that it explodes? It was a
> brand new ACCEL HP coil. The specs on the car again are. The Idle was high
> at the time when I stopped at the lights and applied the brakes it just
> wanted to keep urging forward. Can High Idle cause a problem like this?
>
> thanx
> Damien
--
BREAKFAST.COM Halted... Cereal Port Not Responding.
Joe Davis
would burn points quickly, not hurt the coil. Did you leave the key in the
on position with the engine not running? That will heat up a coil enough to
melt it internally to create a short and get it hot even when the engine is
running. You might have just had a bad coil to begin with. Accel has never
been noted for their customer service so you will probably have to make
several calls and argue to get a response. I had a distributor pickup go
bad after 100 miles and fought with them for 6 months until I gave up and
went with MSD and I'll never buy an Accel product again, not that they have
bad stuff, they just don't back it up with good service.
Dan Timberlake
<mte...@cybertrails.com> wrote:
> Sounds like someone by-passed the resistor wire to the (+ side) of the coil.
>You should be reading about 7 volts not 12, at the positive side of the coil.
>
with the points closed. Points open it will be full 12.6 or whatever.
none...@execpc.com
<nospa...@ulster.net> wrote:
Okay, lets apply a little "Ohms Law" to the above statement....
Volts divided by resistance equals amperage.
The resistance in the primary windings of the Accel is around seven tenths
of an ohm.... possibly less but certainly not more then .7 ohm.
12 divided by .7 = 17.14 amps
at a more realistic system voltage of 14.5...
14.5 divided by .7 = 20.71 amps
like the electrician said when wireing my house...it ain't the volts that
kill ya it's the amps.
lets take it a step further...
volts X amps = watts
12.0 X 17 = 204
14.5 X 20 = 290
How hot will a 200 watt light bulb get?
Now we also need to consider that, when running the current thru the
primary windings is not constant because the primary circuit is being
switched on and off by either the points or the switching transistor in
the control unit
this duty cycle can be any where from about 10 to 48 percent depending
again on whose and what type of control is used..then there is the
frequency, ie; RPMs.
Modern production Distributorless Ignition systems are quite powerful, yet
the peak current usually seen when monitoring the primary of the ignition
coil is in the 6-8 amp range. 6-8 amps seems to be the limit that the
internal components of the control unit are able to handle with any degree
of reliability.
Six amps or 17 amps????? hmmmmmm....
--
Neil Nelson
If you don't believe in something.....
You'll fall for anything....
Member of i-ATN....international Automotive Technicians Network
summer toys; 70 AAR 'Cuda #s match original not restored
see it at.... http://www.geocities.com/MotorCity/9426/photo_pages/orngcuda.html
64 Valiant 340 4bbl
winter toys; 95 Dakota SLT 4X4
88 Toyota Camry AWD
Joe
coils in structions. "Only use the included ballast resistor if a points
type ignition system is used or pre mature failer of points will occur." If
there was a posibility of coil failure they would most certainly mention it
in the instuctions, to cover them selves. Accel coils can also be used with
capacitive discharge ignitions with primary voltages up to 45v. Bypassing
the ballast resistor will kill the points not the coil, it was built run on
up to 16v or up to 55v with a CD ignition. I'm sure Accel's engineers new
Ohms law when they designed them. If the key was left on the coil will get
hot, and could case the windings to partially short causing less resistance
on the primary side, increasing amperage and heat, causing the coil to
eventually explode. Ive used an Accel coil on a race car with a 16v battery
for 5 years before I went to MSD and it never exploded, why????????????
Joe
All Accel coils are for 12v ignitions. I'm sure Accels engineers knew ohms
and kerchief's laws when they designed the coil.
I'm reading from an Accel coils intructoins: "Only use the supplied balast
resisor if a breaker-point ignition trigger is used or premature failure of
the points will occur."
If there was a chance of coil falure they woiuld most certainly mention it
there to cover themselves. Bypassing the resistor will kill the points, not
the coil. Accel claims that there coils will work up to 16v and up to 55v
on cd ignitions, I don't think they'd claim that if there was a chance of
explosion. The thing that limits the amount of voltage that can be used is
the trigger not the coil. capacitive discharge ignitions put over 45v to
the primary side of the coil, Because cd's are modified triggers built to
handle more power, and they pulse the primary terminal with each fire.
If a coils primary side is hot with the engine off and the points are closed
the coil will heat up. It could get hot enouph to short out some primary
windings and cause a lower resistance on the primary side. That would cause
more amperage, more heat and eventually explode the coil.
I used an Accel coil on a race car for 5 years with a 16 volt battery and no
resistor, why didn't it explode??????????? Answer it's built to run up to
16v
I have seen coils explode and most of the time the person had the key on
while checking wiring and it got so hot it blew up.
none...@execpc.com
I guess this reply is to me????
Well I'm quite sure that Accels engineers "new" all about Ohms law also....
however, it appears that *you* do not! Nor do you understand the purpose
of the ballast resistor in the circuit.
Here is a hint.....It has NOTHING to do with voltage!
I posted the formula earlier, there is only one constant...your lesson
exercise is to solve for the correct answer.
Here is the formula again...
E
______
IxR
I know why his coil exploded because I've done the same damn thing
experimenting with different components, mix and match.
At this point, it would help to know what brand and type of ignition
system the original poster was using.....was it points, single or dual?
Was it electronic, what brand?
I believe in an earlier post, someone mentioned that if measuring the
voltage at the coil + terminal, after the resistor with the key on engine
NOT running you would measure battery voltage, but once the engine was
running, the voltage would measure a definite amount lower then battery
voltage. This info is/was correct and the only other clue I'm going to
give.
Joe
meter that has a 1.5v battery to power it. As a coil charges the magnectic
feild builds a higher resistance tappering to infanate ohms if a coil can
fully charge, but us tech guys know that a coil never reaches full charge,
it's impossible. When power is put to the primary side it is just like a
bare wire, the magnetic field bluids resistance over time in a curve. A
very fast curve, the resistance only passes .7 ohms for less tham a
picosecond, An average resistance for a V-8 idling (most charge time) is
about 3.41 ohms with an Accel hp coil. thats a computed fugure, of course
you can't measure it. In other words your measuring the resistance of wire
wound in a coil and your meter can't buils enouph of a feild to make a
resistance bigger than the wire itself. If any thing in your car had .7
ohms resistance it would be considered a short and smoke the batt. because a
plane peace of wire 10ft long has more than .7 ohms resistance, so you'd
touch the two post on a batt. with it. I don't think so it would melt.
You did back my statment as far as the trigger can't take the current. But
you didn't explain why the coil exploded. I say the coil didn't blow due to
the resistor. Tell me how it can.
Joe
knew all about it you would know that ohms law does NOT work with a
electrical magnectic feild at all because it is a forever changing
resistance. You should have learned that in school. The resistor is there
to save the points and you are right they can't take the current, but the
coil can. HEI's do not have one and operate at 13.8 v for thousands of
miles. Explain to me what makes the coil no be able handle full voltage?
Again it's the trigger that can't take the amperage, not the coil. Your
lesson is ohms law works with fixed resisance only. If you would like more
lessons I'd be glad to teach you about electronics. I have a degree form
DeVry.
Instead of just saying I don't know what I'm talking about, try to explain
it to be. I proved your .7 ohm thorey wrong. I f you are wrong I'll tell
you so, and I'll tell you why. Don't start a fight just make valid points
none...@execpc.com
> I know all about ohms laws and exactly why the resitor is there. If you
> knew all about it you would know that ohms law does NOT work with a
> electrical magnectic feild at all because it is a forever changing
> resistance.
Then call it what it is....reluctance....and don't forget to mention that
its effect has more to do with a time delay in voltage/ampereage build up.
Once the coil is saturated there is little opposition to EMF.
The effect doesn't change the results enough to make your position correct
over mine....at 12.6 volts an ignition coil with .3 ohms resistance
*should* flow 42 amps. In reality it *does* flow 40 amps, but drops off to
about 36 amps as the windings heat up. Remember the resistance of copper
wire increases with a rise in temperature.
> You should have learned that in school. The resistor is there
> to save the points and you are right they can't take the current, but the
> coil can.
The resistor is there to save the points in a points system is correct,
but it doesn't do so by controlling voltage, it controls current.
Take a pyrometer and measure the temperature of a ballast resistor when
the engine is idleing, compare that reading to how hot it gets when the
engine is running at 3000 RPM...why is it cooler, the voltage hasn't
changed!
I can't even imagine how voltage would become a concern over amperage,
compare the switches used in an automobile circuit versus the ones used in
a house hold circuit....ten times the voltage yet the household switches
are decidedly lighter duty.
The MoPar Performance catalog lists a 1/4 ohm resistor for use with the
Accel chrome race only coil. They list a 1.0 ohm resistor for use with the
Accel Plastic cased "Super Coil", none of this is based on the type of
trigger system involved/chosen. And yes, this resistance value does not
remain constant when the circuit is operating. An interesting side note
is that the chrome coil is not recommended for use *under 3000* RPM for
over 30 minutes and the "Super Coil" is not recommended for use *above
6500* RPM. Do you know why they publish these warnings?
> HEI's do not have one and operate at 13.8 v for thousands of
> miles.
Well if you are really a degreed student of DeVry you would know that
*ALL* HEI ignition systems have current limiters built into their
circuitry, possibly with the exception of the 'El Gippo' dime store
replacement stuff sold at K-Mart, Walmart, etc. The current limiting is
usually, if not always limited to 6-8 amperes. The other significant
factor concerning HEI ignition is duty cycle....dwell readings are usually
close to one degree for every 1000 RPM so you need to consider the actual
time in seconds (ms) that current is flowing thru the windings between two
different ignition types, HEI at idle = 7-8 degrees of dwell (very short
on time) vs. points type ignition at 30-32 degrees of dwell at idle =
relatively long on time. A Chrysler electronic ignition system will run
around 42-44 degrees of dwell from idle up too redline depending on which
box is used, and it requires a ballast resistor no matter which or what
coil is used. If you bypass the ballast, the coil will explode long before
the switching transistor gives up the ghost....been there, done that!!
Ever measure the rise time of an e-core style HEI coil versus an oil
filled conventional coil? Which one is faster?
Ever consider that an e-core coil is not constrained inside a sealed
vessel like an oil filled coil is. Will anything over flow or burst if an
e-core coil gets a little warm?
> Explain to me what makes the coil no be able handle full voltage?
I don't recall ever posting or voicing an objection to any amount of
voltage to the ignition coil. If you have ever measured the inductive
kick in the primary of an ignition coil you would know that 300 volts is
about the norm, so why would I give a fat rats ass about 12.0, 13.8, 14.5
44.3, etc.
I've had alternators go wild and feed the + side of the coil 200+ volts
and nothing was harmed.
Like Sparky the electrician said, "It ain't the volts, it's the amps".
> Again it's the trigger that can't take the amperage, not the coil.
Which are you going to argue here, volts or amps?
Look at it another way...if I charge a car battery for eight hours at 5
amps, I result in a a recharged battery. If I charge a car battery at 50
amps for eight hours, I have a very big, nasty mess to clean up. Same
voltage both instances.
Try and shove too many electrons thru a pipe and something going to give.
> Your
> lesson is ohms law works with fixed resisance only.
As I said before, the effect inside the coil is minimal, other then for
what period of time the winding are actually allowed to heat up. The only
other variable resistance involved would be the ballast resistor changing
resistance as it heats up and cools down due to the changing on time in
actual seconds (ie;RPM).
If you'd bother to actually make the tests, you'll see that my lesson in
ohms law works surprisingly well in the application being discussed here.
> If you would like more
> lessons I'd be glad to teach you about electronics. I have a degree form
> DeVry.
> Instead of just saying I don't know what I'm talking about, try to explain
> it to be. I proved your .7 ohm thorey wrong. I f you are wrong I'll tell
> you so, and I'll tell you why. Don't start a fight just make valid points
You can start telling me "why" any time now, so far all I've read was some
misunderstood anecdotal instances interspersed with an attempt to
intimidate by technification.
So here it is again...
volts times resistance equals amps, less resistance equals more amps.
volts times amps equals watts, watts equals power. Power in this case
equals heat, as things get hotter they expand.
none...@execpc.com
Well Joe thats nice theory, now go out to the garage and wire it up with
some test equipment attached so you can come back and tell us why it works
differently.
To reword your question.....how can a 1/2 ohm resistor protect a .7 ohm
circuit... (you almost answered your own question here) it can't...because
it isn't always a 1/2 ohm resistor. Could a wire wound resistor heat up
enough to change to a 1.2 ohm resistor? Sure! would it drop the current
enough that the components would live...lets plug it in and see...
With the resistor.....
Coil at .7 ohms + resistor heated to 1.2 ohms = 1.9 ohms
12.6 / 1.9= 6.6 amps X .66 duty cycle (dwell) = average amps of 4.3
With out the resistor....
12.6 / .7 = 18 amps X .66 duty cycle = 11.8 average amps
12.6 x 4.3 = 54.18 watts
12.6 x 11.8 = 148.68 watts
Now, take two light bulbs, one 60 watt and one 150 watt, and place them
against the curtains in your house, turn them both on at the same time and
see which one starts the house on fire first.
Joe
resistor on a HEI without exploding. You can't answer it because the coil
will take the current. The points will fail, not the coil. You sure know
the laws, you just don't know why you're applying them. Do you disagree
that the trigger is the weak part that cant take the current? If so, what
does this have to do with the coil exploding? What you are saying is that
the points cant take 11 amps, well we went over that already. You said the
coil blew up over mismatched part in a previous letter??????? Everything
you wrote so far boils down to the trigger failing due to too much current.
Lets talk about an Accel hp coil, which is built to run with a transistor
trigger, or you can install a ballast resistor to use it with points.
So I ask you mister ohms law:
Why can I use the same coil on an electronic ignition whit no resistor?
Why does Accel recommend NOT using it with HEI?
I'll give you the answers to both: The primary voltage is limited reduce
the current through the trigger.
So stop with ohms law and tell me exactly how a coil will blow up with 14v
going to the pos. term.
So I'm expecting a letter on ohms law and current again. Tell me more how
the points will burn, because that all you seem to know about.
Electronic Ignitions (what the Accel hp coil was built for) run off full
system voltage (without exploding). I'll bet you're still not learning
anything. You would be good at house wiring though.
So you lesson today is an ignition coil is a collapsible circuit that can
take more volts than the alternator can put out. The internal resistance
will limit the amperage (as you know with ohms law)
So think it out before you send another useless post about ohms law.
Joe
protect. Is it the coil? You apparently seem to think so. Or is it the
trigger? I'm going for trigger. Why did the coil explode?????????? The
question that you still can't answer.
Joe
cylinders). Try a 440 V8 with one coil for all eight. Try more like a
19%-23% duty cycle at idle. You must have went to good old automotive
school witch don't tach anything about technology before 1980.
Joe
volts at the coil + terminal (engine running), and their is 6.17 amps
through that same wire. So use your ohms law to figure out resistance on a
running coil. Nothing close to the .7 ohms that you tested with a meter.
Why???? Because your meter can't build a magnetic field to make any
resistance. You cant calculate amperage in running condition based on
measurements of a disconnected coil. You know all the laws, just learn how
to apply them.
The car has an electronic ignition with an MSD blaster coil. Very
compairable to Accel's hp. In case you can't get it it rounds to 2.29 ohms.
And that's with no resistor.
So one more time, the reistor protects the points (because they can't take 6
amps) the coil lives just fine with it.
none...@execpc.com
> All of this still doesn't say why that same coil can be use without a
> resistor on a HEI without exploding. You can't answer it because the coil
> will take the current. The points will fail, not the coil. You sure know
> the laws, you just don't know why you're applying them. Do you disagree
> that the trigger is the weak part that cant take the current? If so, what
> does this have to do with the coil exploding? What you are saying is that
> the points cant take 11 amps, well we went over that already. You said the
> coil blew up over mismatched part in a previous letter??????? Everything
> you wrote so far boils down to the trigger failing due to too much current.
> Lets talk about an Accel hp coil, which is built to run with a transistor
> trigger, or you can install a ballast resistor to use it with points.
Well, I guess your reading and comprehension (u-n-d-e-r-s-t-a-n-d-i-n-g)(
there, I said it real slow) skills are at about a par with your spelling
and grammer skills.
Your claims as to the trigger being the weakest part are highly
subjective, depends on which control, what type of control, and the
quality of components used.
I have already explained the roles played by different dwell schedules as
used in different manufacturers designs.
I have also cited examples of using a high current coil with out ballast
resistor, where the coil failed and the switching transistor (why you
insist on calling it "the trigger"is beyond me) survived.
>
> So I ask you mister ohms law:
>
> Why can I use the same coil on an electronic ignition whit no resistor?
You have yet to mention what brand and application of electronic ignition,
in what type of vehicle.
A wild assed guess is that you (due to sloppy work habits) have yet to
locate where the unwanted voltage drop is on the ground side of the
switch.
> Why does Accel recommend NOT using it with HEI?
>
> I'll give you the answers to both: The primary voltage is limited reduce
> the current through the trigger.
Oh! and I suppose that this will NOT reduce the current thru the
coil....OK genius! Thanks for supporting my position here.
> So stop with ohms law and tell me exactly how a coil will blow up with 14v
> going to the pos. term.
Ahhh...those wonderous comprehension skills of yours rear their ugly head
again, I NEVER said ANYTHING about 14 volts being bad for the coil.
> So I'm expecting a letter on ohms law and current again. Tell me more how
> the points will burn, because that all you seem to know about.
>
> Electronic Ignitions (what the Accel hp coil was built for) run off full
> system voltage (without exploding). I'll bet you're still not learning
> anything. You would be good at house wiring though.
Not according to the MoPar Engine Manual....They are quite specific about
what value of ballast is to be used for which particular Accel HP coil.
> So you lesson today is an ignition coil is a collapsible circuit that can
> take more volts than the alternator can put out. The internal resistance
> will limit the amperage (as you know with ohms law)
>
> So think it out before you send another useless post about ohms law.
No real need to think it out as it is quite a natural event to recite
since I taught the theories and practical applications for enough YEARS
Mr. Admitted Student.
none...@execpc.com
> I took your advice and went out on my car and checked it. There is 14.1
> volts at the coil + terminal (engine running), and their is 6.17 amps
> through that same wire. So use your ohms law to figure out resistance on a
> running coil. Nothing close to the .7 ohms that you tested with a meter.
> Why???? Because your meter can't build a magnetic field to make any
> resistance. You cant calculate amperage in running condition based on
> measurements of a disconnected coil. You know all the laws, just learn how
> to apply them.
Great, wonderful! Thanks for posting the AVERAGE current flowing thru
your coil. Now connect the coil directly to the voltage source, BOTH
positive AND negative, and remeasure the current *WITHOUT* the effect of
the internal current limiting circuitry of the control module and
*WITHOUT* the meter reacting to the off time.
> The car has an electronic ignition with an MSD blaster coil. Very
> compairable to Accel's hp. In case you can't get it it rounds to 2.29 ohms.
> And that's with no resistor.
What kind of car? What kind of ignition system and what was the duty cycle
WHEN you made your measurements. This would be helpful to know in order
for you to understand the reasons you measured values truncated by the
circuitry.
>
> So one more time, the reistor protects the points (because they can't take 6
> amps) the coil lives just fine with it.
--
none...@execpc.com
Do You really believe that a DIS ignition system runs at 66% dwell.....
Yuk Yuk Yuk!!!
Now lets look at the 440 with one coil for all eight cylinders,
A single points ignition would be set for 30-32 degrees of dwell, the
maximum dwell reading on an eight cylinder engine is 45 degrees, 66% of 45
is....Holy shit 29.7 degrees of dwell, got that so far?
The Chrysler ignition boxes run around 42 degrees of dwell, or about 94%
duty cycle.
If you are honestly measureing 19-23% duty cycle in your ignition system
that figures out to be around 8.5-10.3 degrees of dwell....
That is an awful lot of off time for the coil to cool down and
recover....... kind of explains why *YOUR* particular set up didn't or
hasn't blown up , doesn't it?
Geee...turn it on for 10% of the time, leave it off for 90% of the time.....
Too bad they *ALL* do not work that way.......
Ya gotta wonder why the design dictates 90% off time don't cha???????
Could it be to allow the coil to cool off???
Could it be that cooling the coil keeps it from being damaged from heat?
It's been fun ejumakating you!
Joe
and disagree on others You were proven wrong in more than one of your
theories (you still insist on figuring current using ohm measurements made
from a unhooked coil. wrong!!!). I was proven wrong too and some issues.
You where the first to start throwing in cheap shots that don't have
anything to do with the conversation, that's what children do when they're
loosing a game, I thought you were a man. I do understand how a coil can
get hot without a resistor, but an Accel HP coil (the one we were talking
about) can take that abuse. anytime I've ever seen a points ignition
without a resistor, the points burned before the coil. I the proper name is
not a trigger, it's function is to trigger the spark (have you ever called
an engine a motor?), very cheap shots you throw. I used the term duty cycle
wrong, my fault. You were referring to the dwell, but again you used .7
ohms in the same formula. Wrong again!!!!! If you're going to throw out
fancy formulas, at least use them correctly.
The funniest thing is that it seems that I'm the only one here who hasn't
blown up a coil.
For as many ignitions as I've worked on in 30 years, I don't think it's
luck.
So pick apart my grammar on this one, and avoid the fact that you used the
ohms law all wrong.
John Leipold
SNIP
Gary Glaenzer
I was wrong on some things', but NOOOOOOO....you had to make a point that
you were 'less wrong'.....grow up!
Gary in Jacksonville, IL; where Cruise Night is September 26th this year.
............................................................................
........................................
Joe wrote in message <6t0vg8$9g7$1...@supernews.com>...
none...@execpc.com
> It's been fun. Everyone has a different opinion.
Some how you managed to confuse facts with opinion....not surprised!
> We agree on some things
> and disagree on others You were proven wrong in more than one of your
> theories (you still insist on figuring current using ohm measurements made
> from a unhooked coil. wrong!!!).
Ummmm...how again was I proven to be wrong? I gave you results from real
life examples that concluded within *fractions of an ohm* that my
calculations and measurement procedures are/were correct. ie; 12.6/.3 = 42
amps....the actual measured amperage *of the circuit* was in FACT 40
amperes.....
Did you bother to read the post or was your kid at soccer practice?
> I was proven wrong too and some issues.
Yes by myself (see above) and a few others.
> You where the first to start throwing in cheap shots that don't have
> anything to do with the conversation, that's what children do when they're
> loosing a game, I thought you were a man.
Well, here's the way it works....this is usenet, it ain't sunday school or
a tea party. If you post erronious information I or some other person will
call you on it. You continually ignored the examples I had given you, they
weren't opinions they were facts that *I* bothered to verify years ago. I
find it a little more then insulting when I post proof and you choose to
ignore it because there is no physical way that I can push it directly in
front of your face, and if I could, I suspect you'd squeeze your eyes
closed real tight, like this (-) (-) .
My tactics are not the issue in this thread, your inability to admit that
you applied the wrong conclusions are however. Whether or not I am a man
is not the issue either, but your habit of attributing inaccurate
statements to other posters (me in this case) is...you repeatedly
substituted voltage when I posted ampereage. To proud to bother and
verify that your beliefs are wrong, you instead repeatedly re-posted more
messages claiming that I hadn't posted sufficient proof when the circuits
in question *HAD* actually been constructed and measurements made, results
posted back to you.....you still claimed there was no proof....who was on
the losing side of the game?
>I do understand how a coil can
> get hot without a resistor, but an Accel HP coil (the one we were talking
> about) can take that abuse. anytime I've ever seen a points ignition
> without a resistor, the points burned before the coil.
So you wrongly concluded that because the points were acting as a safety
fuse, the coil could suffer no damage under slightly different
circumstances....sheeesh! Here's a news flash...you haven't seen it all
and I haven't seen it all, but I know enough to realize that if it were a
dual point distributor, the points would most likely fuse shut and current
would continue to flow until something went bang! To you everything is
cut and tried according to how your MSD has served you over the years.
> I the proper name is
> not a trigger, it's function is to trigger the spark (have you ever called
> an engine a motor?),
Ummmm actually....NO! Do all the DeVry graduates get the two confused?
> very cheap shots you throw.
Act like a vacuum head, get treated like a vacuum head, or in other words,
your information offered isn't quite in line with your claims of education
> I used the term duty cycle
> wrong, my fault. You were referring to the dwell, but again you used .7
> ohms in the same formula. Wrong again!!!!! If you're going to throw out
> fancy formulas, at least use them correctly.
Ok then explain for me (us) how it is that today I was able to measure 23
amps thru a GM external HEI coil which had a resistance measurement of .55
ohms (as tested with a Fluke 87 DMM) when connected to a 12.5 volt
source??? By your previous claims, it shouldn't have been much over 6
amps.
It wasn't a defective coil, brand new off the storage shelf in my shop.
> The funniest thing is that it seems that I'm the only one here who hasn't
> blown up a coil.
Maybe because you keep making invalid comparisons...like how the coil
survives in your particular application (MSD) which has its own internal
current limiting circuitry (MSD) and short dwell period (MSD or HEI)
against a (I believe it was) a 74 Charger with Chrysler Electronic
Ignition (???) with totally different design and operational
charactoristics. Maybe it's because you haven't considered that the
instructions that come with an Accel coil differ in their recommendations
compared to the instructions that came with your MSD ignition control box
and depending on which one you followed saved you from connecting a
ballast resistor into the circuit that wasn't required. Remember, I never
said that the ballast was required in *ALL* applications, I did however
post information that was applicable to the original posters complaint
(which it appear is actually the result of some truely screwed up
wireing).
> For as many ignitions as I've worked on in 30 years, I don't think it's
> luck.
Nothing, and I mean NOTHING surprises me anymore.
> So pick apart my grammar on this one, and avoid the fact that you used the
> ohms law all wrong.
The fact that you still do not understand how the ignition components
involved operate is hardly proof that I have misapplied ohms law.
But feel free to send out warnings to all the auto and component
manufacturers informing them that you *believe* that all of the
specifications they have published over the last umpteen years is "all
wrong". Those guys working deep in the bowels of the engineering
department need a good laugh now and then (or so they tell me).
John Hamm
>
> The funniest thing is that it seems that I'm the only one here who hasn't
> blown up a coil.
>
Snip, snip, OUCH!
Now, now. I've never blown one up either.
--
John Hamm Buy/Sell/Trade
Vinyl, CDs, R2R tapes, Equipment, Literature
Motorcycles (Suzuki GT-750 Water Buffalos)
http://www.sunflower.com/~jlhamm/main.htm
Joe
childish remarks. I was wrong about the duty cycle. Everyone here has made
good and bad points (including me, and yes including others). I do still
consider all of us technicians, this is how we learn more about our jobs.
I'll bet everyone here has learned something. Next time there's a
disagreement I promise I will not be the first to throw a cheap shot, an I
will respect constructive criticism.
Can we all make this promise? Lets all grow up ok?
The replies to this post will separate the men from the children.
Charles Cochran
friend of mine blew up one by connecting it to 220 house supply
current. He had to go get some bits of the shell removed from his butt
afterward. I think he was trying to build an electric fence for his
horses if I remember correctly.
I've worn a bunch out and the closest to blowing one was on a M-52A1
Jeep in my Nat. Guard unit when I accidentally applied 24 volts to a
non-military coil (6 v G.M.). It smoked a little.
Btw, Ohm's Law will allow accurate calculation of current flow based on
applied voltage and measured resistance. Where a coil causes trouble is
that it's a very basic auto-transformer operating on collapsing magnetic
fields. You start with a regulated( by circut resistance) current flow
generating a strong magnetic field in the transformer. When the current
flow ceases, the field collapses inducing a higher voltage in the
secondary windings thus creating a spark.
The collapsing magnetic field is very basic to and required for any
transformer to work. It happens, for example, at a rate of 120 times
(A.C. current cycles 60 times a second giving 120 collapses/sec as the
current reaches the null point and reverses polarity) a second in the
transformer that supplies your home. Just take an ordinary
audio-transformer hook a voltmeter to the output leads and a flashlight
battery to the primary side. You may read voltage as you make or break
the battery side of the circut, but once connected you will read no
voltage.
Now can we shut up about who's right and who's wrong?
To check my description and experiment, pick up nearly any good 6th
grade level electronics book. It's all probably in there.
Budd
Joe wrote:
>
> It's been fun. Everyone has a different opinion. We agree on some things
> and disagree on others You were proven wrong in more than one of your
> theories (you still insist on figuring current using ohm measurements made
> from a unhooked coil. wrong!!!). I was proven wrong too and some issues.
> You where the first to start throwing in cheap shots that don't have
> anything to do with the conversation, that's what children do when they're
> loosing a game, I thought you were a man. I do understand how a coil can
> get hot without a resistor, but an Accel HP coil (the one we were talking
> about) can take that abuse. anytime I've ever seen a points ignition
> without a resistor, the points burned before the coil. I the proper name is
> not a trigger, it's function is to trigger the spark (have you ever called
> an engine a motor?), very cheap shots you throw. I used the term duty cycle
> wrong, my fault. You were referring to the dwell, but again you used .7
> ohms in the same formula. Wrong again!!!!! If you're going to throw out
> fancy formulas, at least use them correctly.
>
> The funniest thing is that it seems that I'm the only one here who hasn't
> blown up a coil.
> For as many ignitions as I've worked on in 30 years, I don't think it's
> luck.
>
Joe
the good :) work :)
Grape Ape
all this. I seen Joe admit he mad a mistake once and you just keep going
throwing more info at us that doesn't matter.
I believe him, I've never seen a coil explode from not using a resistor
either. This is what it all started over, right? he said that the points
would burn up before the coil. And so far it seems you have been proven
wrong on that.
I also agree that children call each other names when they loose an
argument. If you weren't so defensive and so quick to try and belittle
someone you might make a point.
But I just see you as an asshole, you started in with a stuck up know it all
attitude. You have no respect from me.
You really acted like a kid especially when you got a friend to back you
(little kids are the cruelest when they team up). There have been post from
other people saying he is wrong too.
You said you were a teacher in one of your posts. Let me know were so I
don't send my son there. A teacher should help not criticize.
J-Bone
up. You are being a jerk.
This has been going on for a while (too long). I've been testing coils as
you two have been fighting and 90% of my conclusions were closer to Joes,
not yours, so give it up.
Please don't start taking shots at me. As a matter of fact I wont let you.
This is the last time I click on EXPLODING COIL!!!!!!!!
none...@execpc.com wrote in message <6t1j97$l...@newsops.execpc.com>...
John
nothing. You made fun of him when he mentioned MSD and now your bringing in
GM HEI??? You change you story evetime there's a post.
If I was you, I'd get off the news group for a while to let people forget
what an ASS you are.
YOU WERE WRONG TOO, HA HA HA HA HA.
Smitty
>Some how you managed to confuse facts with opinion....not surprised!
>Ummmm...how again was I proven to be wrong? I gave you results from real
>life examples that concluded within *fractions of an ohm* that my
>calculations and measurement procedures are/were correct. ie; 12.6/.3 = 42
>amps....the actual measured amperage *of the circuit* was in FACT 40
>amperes.....
>Did you bother to read the post or was your kid at soccer practice?>
>Yes by myself (see above) and a few others.
>Well, here's the way it works....this is usenet, it ain't sunday school or
>a tea party. If you post erronious information I or some other person will
>call you on it. You continually ignored the examples I had given you, they
>weren't opinions they were facts that *I* bothered to verify years ago. I
>find it a little more then insulting when I post proof and you choose to
>ignore it because there is no physical way that I can push it directly in
>front of your face, and if I could, I suspect you'd squeeze your eyes
>closed real tight, like this (-) (-) .
>My tactics are not the issue in this thread, your inability to admit that
>you applied the wrong conclusions are however. Whether or not I am a man
>is not the issue either, but your habit of attributing inaccurate
>statements to other posters (me in this case) is...you repeatedly
>substituted voltage when I posted ampereage. To proud to bother and
>verify that your beliefs are wrong, you instead repeatedly re-posted more
>messages claiming that I hadn't posted sufficient proof when the circuits
>in question *HAD* actually been constructed and measurements made, results
>posted back to you.....you still claimed there was no proof....who was on
>the losing side of the game?>
>So you wrongly concluded that because the points were acting as a safety
>fuse, the coil could suffer no damage under slightly different
>circumstances....sheeesh! Here's a news flash...you haven't seen it all
>and I haven't seen it all, but I know enough to realize that if it were a
>dual point distributor, the points would most likely fuse shut and current
>would continue to flow until something went bang! To you everything is
>cut and tried according to how your MSD has served you over the years.
>Ummmm actually....NO! Do all the DeVry graduates get the two confused?
>Act like a vacuum head, get treated like a vacuum head, or in other words,
>your information offered isn't quite in line with your claims of education
>Ok then explain for me (us) how it is that today I was able to measure 23
>amps thru a GM external HEI coil which had a resistance measurement of .55
>ohms (as tested with a Fluke 87 DMM) when connected to a 12.5 volt
>source??? By your previous claims, it shouldn't have been much over 6
>amps.
>It wasn't a defective coil, brand new off the storage shelf in my shop.
>Maybe because you keep making invalid comparisons...like how the coil
>survives in your particular application (MSD) which has its own internal
>current limiting circuitry (MSD) and short dwell period (MSD or HEI)
>against a (I believe it was) a 74 Charger with Chrysler Electronic
>Ignition (???) with totally different design and operational
>charactoristics. Maybe it's because you haven't considered that the
>instructions that come with an Accel coil differ in their recommendations
>compared to the instructions that came with your MSD ignition control box
>and depending on which one you followed saved you from connecting a
>ballast resistor into the circuit that wasn't required. Remember, I never
>said that the ballast was required in *ALL* applications, I did however
>post information that was applicable to the original posters complaint
>(which it appear is actually the result of some truely screwed up
>wireing).
>Nothing, and I mean NOTHING surprises me anymore.
none...@execpc.com
<jlh...@lawrence.ks.us> wrote:
> Joe wrote:
> >
> > The funniest thing is that it seems that I'm the only one here who hasn't
> > blown up a coil.
> >
>
> Snip, snip, OUCH!
>
>
> Now, now. I've never blown one up either.
>
>
> --
> John Hamm Buy/Sell/Trade
> Vinyl, CDs, R2R tapes, Equipment, Literature
> Motorcycles (Suzuki GT-750 Water Buffalos)
> http://www.sunflower.com/~jlhamm/main.htm
Have you ever tried to get one to blow up?
none...@execpc.com
> The replies to this post will separate the men from the children.
Sounds like a good idea, and no I'm not posting this as a way to suck up
or prove to ANYONE whether or not I'm an asshole. It's a discussion guys!
Anyone, and I mean anyone who has participated in this group for any
period of time knows that I will admit when I am wrong.
If you *really* want to see what a bunch of children look like then just
subscribe to milw.general
Y'all have a nice week now!
none...@execpc.com
> You're not alone. I've never "blown" up a coil in a civilian vehicle. A
> friend of mine blew up one by connecting it to 220 house supply
> current. He had to go get some bits of the shell removed from his butt
> afterward. I think he was trying to build an electric fence for his
> horses if I remember correctly.
Gee, never thought to hook one up to 220 house current, A+ to your friend
for thinking that one up.
<snipped>
>
> Now can we shut up about who's right and who's wrong?
In the name of peace and quiet, and to quell the infighting amongst the
troops, I'll second the motion
>
> To check my description and experiment, pick up nearly any good 6th
> grade level electronics book. It's all probably in there.
>
> Budd
>
Gotta go.....now where did I stash that old dryer cord???? 8^)
none...@execpc.com
> What are you trying to prove?? Whatever it is, you aren't proving a thing,
> nothing. You made fun of him when he mentioned MSD and now your bringing in
> GM HEI??? You change you story evetime there's a post.
>
> If I was you, I'd get off the news group for a while to let people forget
> what an ASS you are.
>
> YOU WERE WRONG TOO, HA HA HA HA HA.
Looky here,
A post from AOL, and only one line is all caps!
Ya think there is hope for the world?
John
Accel HP coil is a direct replacement for that very coil. It is also a
direct replacement for a points system (providing you use the resistor).
Now, you said that 14.5 volts divided by .7 ohms equals 20.71 amps (not
taking into account the off time). You also said that was too much it
should be more like 6-8. So an accel coil can handle that amperage, that
means Joe was right, it wouldn't hurt that coil (he didn't say all, he
specifically said an Accel HP coil). That is way to much amperage for the
points. I called Summit because of all this and they agreed, the coil will
live under those circumstances. So I disagree with you. As far as
measuring coils amps with the test ohms I've always came 2-4 amps off form
real life measurements, so again I agree with him, it's not 100% accurate.
I measured a coil with .57 ohms resistance with 12.8 volts system voltage
(no resistor), the MSD trigger (switch) states on the instructions has .1
ohms resistance. Using your method I come up with 19.1 amps, Actual amps
was 17, so what did I do wrong, I double-checked and had another technician
check it, it's just not 100% accurate. Joe said that he knew that a coil can
heat up do to low resistance, but that particular coil will live (points
wouldn't last to long). Yes, you guessed it, I agree.
One thing I recommend to you, and this is not a cheap shot, learn some slang
terms. You seem to have a problem knowing what everyone is saying because
they don't use the exact name for it. I knew what they were talking about
when they said "trigger". You went off the deep end when you heard that. I
have called an engine a motor and so has 99% of the U.S.
Joe has given me some very accurate advise in the past on this news group
and saved me a lot of money and aggravation fining problems. So far he has
never steered me in the wrong direction.
Maybe you do know your stuff, but you'll never get any points across acting
like you do.
none...@execpc.com
> You said that you measured 23 amps through a external GM HEI coil right?
Yes, although the ammeter doesn't display tenths of an amp so it may have
been slightly higher or lower (insignificant)
> An
> Accel HP coil is a direct replacement for that very coil. It is also a
> direct replacement for a points system (providing you use the resistor).
> Now, you said that 14.5 volts divided by .7 ohms equals 20.71 amps (not
> taking into account the off time).
John, if you are trying to make it appear that my numbers contradict
themselves, here is exactly what I posted in reference to measurements of
the HEI external coil
################################################################################
In article <6t1j97$l...@newsops.execpc.com>, none...@execpc.com wrote:
> Ok then explain for me (us) how it is that today I was able to measure 23
> amps thru a GM external HEI coil which had a resistance measurement of .55
> ohms (as tested with a Fluke 87 DMM) when connected to a 12.5 volt
> source??? By your previous claims, it shouldn't have been much over 6
> amps.
> It wasn't a defective coil, brand new off the storage shelf in my shop.
################################################################################
> You also said that was too much it
> should be more like 6-8.
No, I said "By your previous claims, it shouldn't have been much over 6
amps." To refresh your memory, Joe had gone to his MSD equiped car, hooked
up an ammeter, started the car and at idle measured somewhere around 6
amps. He then used ohms law and calculated from that 6 amps and a system
voltage measurement, a resistance reading somewhere in the 2.2-2.3 range.
The reason he saw only 6 amps is a result of the current limiting
circuitry inside the MSD control box, not because of the magnetic field
inside the coil creating inductive reactance.
To clarify, I'm not saying that the inductive reactance doesn't exist, I'm
saying that that is not what he observed.
> So an accel coil can handle that amperage, that
> means Joe was right, it wouldn't hurt that coil (he didn't say all, he
> specifically said an Accel HP coil). That is way to much amperage for the
> points. I called Summit because of all this and they agreed, the coil will
> live under those circumstances. So I disagree with you. As far as
> measuring coils amps with the test ohms I've always came 2-4 amps off form
> real life measurements, so again I agree with him, it's not 100% accurate.
> I measured a coil with .57 ohms resistance with 12.8 volts system voltage
> (no resistor), the MSD trigger (switch) states on the instructions has .1
> ohms resistance. Using your method I come up with 19.1 amps, Actual amps
> was 17, so what did I do wrong, I double-checked and had another technician
> check it, it's just not 100% accurate.
John, I don't think you did anything wrong, lets find out what happened to
the missing amperage. You have two numbers to use, lets solve for the
third and fourth....
12.8 volts divided by the 17 amps you measured equals .75 ohms. By using
your ammeter and voltmeter you have determined that the dynamic resistance
of the circuit is .75 ohms (third). You measured/ figured it to be .67
ohms (.57 for the coil and .1 for the switch). subtract the .67 from .75,
equals .080 ohms (fourth),
eight onehundredths of an ohm accounts for the discrepancy in what you
calculated using ohms law versus what you measured with your ammeter.
I didn't just prove the minimal effect of inductive reactance in an
ignition coil....YOU DID!!
To compare how far off Joe and I are on the numbers, use this analogy.....
I tell you to gap your spark plugs at eighty thousandths of an inch.
Joe tells you to gap your spark plugs at one and one half inches.
This is only a comparative analogy, I'm not accusing Joe of saying plugs
should be gapped that wide...save the flames please!
> Joe said that he knew that a coil can
> heat up do to low resistance, but that particular coil will live (points
> wouldn't last to long). Yes, you guessed it, I agree.
Any coil will live in a hot condition until one of two things happen, 1)
it reaches the boiling point of the oil inside (if it's an oil filled
coil) and 2) it reaches the temperature that will melt the varnish off of
the windings and short out. As far as I know, and I may be wrong, the
coil that was originally being discussed *is* an oil filled coil....that
oil is very toxic to humans, again AFAIK. I will always choose to err on
the side of caution.
> One thing I recommend to you, and this is not a cheap shot, learn some slang
> terms. You seem to have a problem knowing what everyone is saying because
> they don't use the exact name for it. I knew what they were talking about
> when they said "trigger". You went off the deep end when you heard that. I
> have called an engine a motor and so has 99% of the U.S.
I knew full well what the slang terms Joe was using meant. The problem is
that although he had claimed to have a Degree from DeVry Institute, he
sure didn't sound like it. Secondly, while I consider flames about
spelling and grammer to be extremely boorish, I also believe that you and
I and everyone else reading this newsgroup deserve the respect and
courtesy of at least a quick proof read before hitting the send button,
those are my own personal feeling and surprisingly, according to some of
the e-mail I've recieved, the feelings of quite a few others.
> Joe has given me some very accurate advise in the past on this news group
> and saved me a lot of money and aggravation fining problems. So far he has
> never steered me in the wrong direction.
>
> Maybe you do know your stuff, but you'll never get any points across acting
> like you do.
Do ya Think??? Well John it got you to reply again, in further search of
an understanding of what was being discussed here, and I mean that in a
nice way!
Look at it like this....When you were in school, which teachers were your
favorite? The ones that just stood at the front of the classroom and
droned and droned, on and on, no accent on a sylable or the ones that kept
it interesting and dynamic? Assuming of course you weren't there to catch
up on your ZZZZZZs.
Blackhawk
caused the oil (used to cool the coil) to get hot enough to explode. Pretty
simple really...
Gary
John Leipold wrote in message <6t1a2l$4pj$3...@supernews.com>...
Chris REMOVE DUCKBUTTER
>ignition systems are `explosion proof` with a rubber plug to pop out in the
>event of a short circuit before an explosion could result. Great
>reliability in electronic ignition systems!
Yet another hint--Bosch "blue" coils for air-cooled VWs are also internally
ballasted and provide like 40,000V!! I've run them on many american-type
watercooled cars. They're the most reliable coil I've ever run.
Joe
consider 12% minimal. What happened to the rest of the current? We
straightened out how the coil works already, upon initial contact the coil
has the most impedance. Then the impedance goes down as the magnetic field
is built, as the field is built the amperage goes up until saturation is
achieved. When you figure amperage through a coil, you must consider the
time it takes for this to happen (that time must be figured in with the
average current flow). The average impedance makes up for that .08 ohms.
Now, if the coil does not have time to fully saturate, than maximum current
is not achieved. So as rpms increase, the coil has less time to charge (as
we proved in the Now we're getting somewhere post), and that reduces
amperage(the formula you used doesn't take that into account). It is very
significant as rpms rise.
Now lets look at an MSD box. I'm going to leave the multiple sparks out
right now. I was using ohms law to calculate resistance from measured
amperage and voltage. That is how you said to do it (this is before duty
cycle came in). MSD have no resistance (at least not enough to worry about
right now). MSDs do not only switch the neg. side of the coil, at low rpms
they delay power to the pos. side. When the - side of the coil switch opens
there's a spark. than the + side switch opens also on an rpm sensitive
delay,. Then the + and - sides close (allowing the coil to do its thing).
Than it starts over. After about 2500 rpm, that delay taper to a pretty
much steady voltage to the + side. That is a much better design than a
resistor. I didn't say that all ignitions were the same I just said that
ohms law doesn't work in figuring real running average amperage through the
coil (which is how you were doing it). I'm sorry I made more confusion with
the MSD reference.
Now let me explain what I consider duty cycle. You measure duty cycle as on
time. I measure it as real life amperage as compared to calculated using
the ohms law. Not only do you consider the dwell but also the time it takes
to build the current and when maximum current (saturation) is not achieved.
My figures are much lower than yours because of that. I never said that my
ignition ran at 10 degrees of dwell, that was you figure not taking into
account all the variables. If you want to post average current flow through
a coil, you must consider all the variables and the entire rpm range,
that's where our #'s conflicted. On a test bench with power to the positive
side and the negative side grounded ohms law works, because the coil has
reached saturation. That is not running on an engine though.
Grape Ape
owe's a big apology for calling you stupid. You obviously know more than
him. Right Nelson?
Nelson was right (as far as he got), but Joe took it a few steps further.
Nobody's perfect.
Grape Ape
>
>Anyone, and I mean anyone who has participated in this group for any
>period of time knows that I will admit when I am wrong.
>
about him and called him all kinds of names, basically calling him retarded,
and he was right.
I think everyone will have more respect for you if you either admit it, or
prove him wrong.
All of us who didn't know how this stuff worked, now does. I'm pretty clear
on how it works, so this discussion had a good purpose.
Is anyone not clear on how a coil works?
none...@execpc.com
wrote:
OK, if you insist...and you appear to be quite insistant!!
let's start here.....a post from Grape Ape detailing the results of his
and Joes tests on his car.....
> 1 - He measured the primary resistance. .63 ohms
>
> 2 - We ran the car and took a voltage reading to get actual running voltage.
> 13.7 volts
>
> 3 - He calculated current, 13.7 / .63 = 21.746 amps
> 4 - Then he set his fancy machine up and adjusted it to 13.7 volts and
> double checked it using the same meter. Yes actual amps was 21.75 -
> perfect. But that's with no off time figured into the average amperage
> trough the coil
>
> 5 - Now add the off time. we measure dwell at exactly 32 degrees. All
> eight cylinders means 256 degrees of on time. He figured that into .71 duty
> cycle. Right?
>
> 6 - 21.746 amps x .71 duty cycle = 15.44 amps. Right?
>
> 7 - With the engine running (no resistor), I should read 15.44 amps through
> the coil. Right?
>
> 8 - Wrong. I read 13.67 at 1000 rpm, and the more I revved it the lower it
> went.
>
> 9 - Why? Joe explained, not using his exact words, when the coil is fully
> charged (or saturated), it is at it's peak amperage, bit it doesn't have
> time to fully charge, even if it did, you still have to take into account
> the time that it takes to reach full current (because it takes that same
> time to build the current every time the points close), because that reduces
> the average amperage through the coil.
You were doing just fine until # 5.... Yes 32 degrees of dwell would
result in the multiplier of .71....problem is you can't use the raw dwell
number....
Why?? read # 9 again.....Joe is exactly correct in his explaination, but
why didn't he apply it to the experiment??? Beats me! Dwell includes coil
rise time (the effect Joe describes in #9) .....
I was really hoping you two would catch your error and re-run the numbers
based on coil saturation time.
The previous numbers that I posted were taken from actual running tests,
the .66 duty cycle (which = 30 degrees of dwell) was the actual max
saturation time that was measured on a vehicle that had an engine running
dwell measurement of 42 degrees. In other words, on the vehicle that I
tested on, 12 degrees of the dwell event are low current, some portion of
that 12 degrees should not be used in the equation.
Yup! I neglected to mention that one little tid-bit, and I fully admit
that I did it on purpose.
There is another point I would like to make.... When dealing with
electrical circuits, the end result will most likely NOT agree EXACTLY
with the values that you measure and plug into the formula in the
beginning, tolerances, differences in measuring equipment, the effects of
heat in a wire or circuit will all skew the final readings slightly.
So I guess two people plugging erronious numbers into their formula makes
me an asshole......hey what ever gets you guys off!
Grape Ape, you were correct, Joe did take it a step further..........
Just not far enough.
Y'all have a nice week now!!
John
stuff works exactly. How does dwell include that lower current time? I
thought dwell was just a measurement of how long a coil has to saturate,
measured in degrees of distributor rotation. I thought that it just
measured on time, compared to off. Like I said I'm not sure, I would just
like to learn more. what makes up dwell on electronic ignitions? Is it the
air gap on the pickup? Or is it in the control module? I would like to
know what dwell my MSD 6AL has so I can try to figure this stuff out. My
dwell meter flips out when hooked to my coil.
Grape Ape
and will be back in 3 weeks. I'll ask that question to him when I see him.
As far as electronic ignitions. It's the module, the magnetic pickup
creates an AC voltage (just like anti-lock brake sensors), that frequency
tells the ignition module what rpms and where the distributor is and it's
converted into an on/off switch by the module, and does the same thing that
the points would do. That's the basic idea (might not be exact), I'm sure
someone will post the exact technical way it's done. Moving the air gap
will weaken or strengthen the signal, but the frequency will be the same
(pretty sure, not 100% sure). Someone tell me if I'm wrong.
MSD boxes are not the way to start learning, They switch the positive
terminal and also have much higher voltages at the positive terminal of the
coil. MSD's also have multiple sparks that are a result of switching the
positive terminal on and off quickly. That's why your dwell meter is not
reading correctly. Tachometers cannot read the multiple sparks either,
that's why the box has it's own tach connector rather that using the coil
(some tach's still flicker due to this).
You would be better starting out with a regular HEI so you get the basics
down. I don't fully understand about MSD, Joe's the pro on them, I seen him
working out the ignition plan on his Outlaw Street Camaro and he lost me
after 10 seconds. That plan included a MSD 10 box and since charging
systems were required, he put one on the rear end that ran off the
driveshaft. I don't know that logic, but since then, I've seen 4 other
teams do it. That car ran deep into the 6's and over 200 mph. If he left
something out of the formula, it was done to make a point. I'm sure he
knows how to figure this stuff. He figures everything out to the point of
being annoying.
John wrote in message <6tkbjk$8cl$1...@supernews.com>...
none...@execpc.com
> I would like to but into this and ask a question. I don't know how all this
> stuff works exactly. How does dwell include that lower current time? I
> thought dwell was just a measurement of how long a coil has to saturate,
> measured in degrees of distributor rotation. I thought that it just
> measured on time, compared to off. Like I said I'm not sure, I would just
> like to learn more. what makes up dwell on electronic ignitions? Is it the
> air gap on the pickup? Or is it in the control module? I would like to
> know what dwell my MSD 6AL has so I can try to figure this stuff out. My
> dwell meter flips out when hooked to my coil.
Good questions John,
First thing to understand is, dwell is a function of voltage over time
over distributor degrees of rotation, the voltage reaction when the
switch(either points or transistor) opens or closes is immediate, the
effect on current is a little different. The current builds rather slowly
when the switch closes, this is rise time, it takes a few milliseconds
(thousandth of a second) for the current to increase, when the switch
opens the current collapses immediatly.
The total dwell schedule on electronic ignition systems is controled by
the circuitry inside the module, and is often monitored and adjusted
slightly by that circuit, this is called "closed loop dwell control" in
some factory systems. Both Ford and GM have used this type of ignition
module in certain applications over the years. The MSD s a whole different
animal, like you said, it tends to drive test equipment crazy and is not a
good set-up to use in the comparisons in this discussion. Not saying it
isn't a good ignition.....just hard to use for discussion....
When viewed on an oscilliscope, the primary voltage (dwell) and current
patterns look something like the drawing below.....
__________ ____________________ dwell
I I
I__________________I
/-----------------I
__________/ I____________________current
The start and end of the event occur at the same time, but the peaks occur
at different times. How high the current ramps up to is controled by the
module in some electronic ignitions, in others it is controled by a
ballast resistor.
Chrysler Electronic Ignition uses such a ballast to control the primary
current, so does the older Ford Dura Spark and SSI ignition. Some Chrysler
systems do not use a ballast, this started around 1978 when the pick-up in
the distributor was redesigned to a hall-effect switch to control the
module, the dwell event is much shorter on these systems.
MCD
time? It can't. Dwell is simply the number of degrees that the coil has to
charge, period. A dwell meter has nothing to do with current rise time, it
has to do with points on or off. When the points are closed, a dwell meter
reads nothing, why? Because a dwell meter has around 10,000-12,000 ohms
resistance, and current will take the easiest path (through the points)
totally bypassing the meter. When the points open there is now a slight
amount of current through the meter (not enough to hold the magnetic field,
that's the purpose of the resistance, if it had no resistance the field
wouldn't collapse and the engine can't run). There is just enough current
to get a reading. The meter measures when the points are open (off time).
So how will it know what goes on with the points closed? It uses the off
time to figure the on time (that's what's left). Dwell doesn't include
saturation time at all (it can't). A dwell meter can't even tell you how
many cylinders you have, you must look at the right scale to know. It tells
you on time (by measuring off time and telling you what's left), than the
scale on the meter must be in the right place to read for a certain number
of cylinders.
John, you were right, dwell is a measurement of the amount of time a coil
has to saturate, measured in distributor degrees, nothing more.
Nelson, you are wrong again, they were 100% correct in there experiment, and
their conclusion was exactly right. If dwell included saturation time than
dwell would change by just replacing the coil with one that takes a
different amount of time to saturate.