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  #1   Report Post  
Backlash
 
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Default Ignition coil

My forklift has the older, cylindrical shaped ignition coil, with a 12 volt
system. The coil was using an external resistor when I got the lift truck.
It is now wired to get 12 volts when starting, and it fires up INSTANTLY. It
then drops back to the resistor for running. However, after starting the
engine with half choke and running for a couple of minutes, I push off the
manual choke. As the engine warms up, you can hear cylinders "coming in"
that weren't running properly before. A plug check found smutty plugs, but
the engine runs relatively well after the "clearing out" occurs. The engine
should not be over-choked, because I am just choking it enough to keep it
running as well as possible, no black smoke exhausting, etc. I am wondering
if the resistor is cutting back on the coil too much, affecting my spark
after startup and during running. The coil has no markings. I am thinking
about bypassing the resistor to see if things improve, but I obviously don't
want to burn up the coil. Does anyone have any info on how to tell if a coil
really NEEDS an external resistor? Any ohm readings I can take to tell if
it's a coil that can be run without a resistor at 12 volts?
Thanks for any helpful info.

RJ

--
"Have no one say it, and say it to your shame, that all was well here, until
YOU came."





  #2   Report Post  
Terry Coombs
 
Posts: n/a
Default

Backlash wrote:
My forklift has the older, cylindrical shaped ignition coil, with a
12 volt system. The coil was using an external resistor when I got
the lift truck. It is now wired to get 12 volts when starting, and it
fires up INSTANTLY. It then drops back to the resistor for running.
However, after starting the engine with half choke and running for a
couple of minutes, I push off the manual choke. As the engine warms
up, you can hear cylinders "coming in" that weren't running properly
before. A plug check found smutty plugs, but the engine runs
relatively well after the "clearing out" occurs. The engine should
not be over-choked, because I am just choking it enough to keep it
running as well as possible, no black smoke exhausting, etc. I am
wondering if the resistor is cutting back on the coil too much,
affecting my spark after startup and during running. The coil has no
markings. I am thinking about bypassing the resistor to see if things
improve, but I obviously don't want to burn up the coil. Does anyone
have any info on how to tell if a coil really NEEDS an external
resistor? Any ohm readings I can take to tell if it's a coil that
can be run without a resistor at 12 volts? Thanks for any helpful
info.

RJ


The resistor is more to extend point life . Even with a capacitor to
absorb the surge , 12v will fry the points . You might try a Chevy ballast
resistor . Are you sure it doesn't use a resistance wire to the coil ? Too
much resistance will surely weaken the spark .

--
Snag aka OSG #1
'76 FLH "Bag Lady"
BS132 SENS NEWT
"A hand shift is a manly shift ."
shamelessly stolen


  #3   Report Post  
Greg Menke
 
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Default

"Backlash" writes:

My forklift has the older, cylindrical shaped ignition coil, with a 12 volt
system. The coil was using an external resistor when I got the lift truck.
It is now wired to get 12 volts when starting, and it fires up INSTANTLY. It
then drops back to the resistor for running. However, after starting the
engine with half choke and running for a couple of minutes, I push off the
manual choke. As the engine warms up, you can hear cylinders "coming in"
that weren't running properly before. A plug check found smutty plugs, but
the engine runs relatively well after the "clearing out" occurs. The engine
should not be over-choked, because I am just choking it enough to keep it
running as well as possible, no black smoke exhausting, etc. I am wondering
if the resistor is cutting back on the coil too much, affecting my spark
after startup and during running. The coil has no markings. I am thinking
about bypassing the resistor to see if things improve, but I obviously don't
want to burn up the coil. Does anyone have any info on how to tell if a coil
really NEEDS an external resistor? Any ohm readings I can take to tell if
it's a coil that can be run without a resistor at 12 volts?
Thanks for any helpful info.


Since the resistor is external, you might put a 2nd one in parallel
with it, more or less halving the effective resistance. I'd hesitate
to simply pull the resistor altogether, the coil would likely overheat
if you ran it that way for more than some few seconds.

I'd measure the resistor and find a wirewound of similar resistance
good for 10 to 20 watts- Radio Shack might still be carrying them
these days. At one point they sold dummy speaker loads- basically
just an 8 ohm resistor that could take a good deal of power.

I have automotive coil with internal resistor, shows about 4 ohms on
my meter. A resistorless coil should have very low resistance, less
than 1 ohm I'd think- I've never measured one. You might doublecheck
that your coil doesn't have an internal resistor already- perhaps the
original resistorless coil was replaced at some point by a unit w/
internal resistor and now you're running with something like double
the resistance.

Gregm

  #4   Report Post  
Anthony
 
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Default

"Backlash" wrote in
:

My forklift has the older, cylindrical shaped ignition coil, with a 12
volt system. The coil was using an external resistor when I got the
lift truck. It is now wired to get 12 volts when starting, and it
fires up INSTANTLY. It then drops back to the resistor for running.
However, after starting the engine with half choke and running for a
couple of minutes, I push off the manual choke. As the engine warms
up, you can hear cylinders "coming in" that weren't running properly
before. A plug check found smutty plugs, but the engine runs
relatively well after the "clearing out" occurs. The engine should not
be over-choked, because I am just choking it enough to keep it running
as well as possible, no black smoke exhausting, etc. I am wondering
if the resistor is cutting back on the coil too much, affecting my
spark after startup and during running. The coil has no markings. I
am thinking about bypassing the resistor to see if things improve, but
I obviously don't want to burn up the coil. Does anyone have any info
on how to tell if a coil really NEEDS an external resistor? Any ohm
readings I can take to tell if it's a coil that can be run without a
resistor at 12 volts?
Thanks for any helpful info.

RJ


RJ,
You didn't mention who the manufacturer of the engine was, and that would
be helpful information. My suggestion is a trip to the junkyard...to
find an electronic system from a later model year. Failing that, you
could always go with an aftermarket electronic conversion kit for the
distributor, and something like an MSD or Jacobs ignition kit.
Changing over would provide a reliable, high-voltage, stable spark and
performance, better economy, less maintenance.
Be sure to open the spark gap up to what the electronic system was
designed to run with. (This should gain you some power to boot.)

--
Anthony

You can't 'idiot proof' anything....every time you try, they just make
better idiots.

Remove sp to reply via email
  #5   Report Post  
Karl Townsend
 
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Default

You might use a new approach. Put in retrofit electronic points and change
to a coil without a resistor.

THIS IS SO MUCH BETTER! I live in MN and I've changed all my old tractors
over. Now they all start if the battery can kick it over and I haven't
replaced points in years.

This will cost you about $100. Any autoparts store can order them. I
couldn't find it, but there's an online website to get them cheaper, just
for tractor restore.

Karl





  #6   Report Post  
Backlash
 
Posts: n/a
Default

Thanks all, for your valuable input. Problem is, right now I'm in the middle
of loading my entire workshop into a semi trailer I bought, so needed a
quick solution. Wife got a promotion, we're moving, and at the same time, a
friend bought out my workshop property, so I had to clear that out also. I
think I'll measure the resistance of the coil, and see If I think I can
eliminate the resistor. I haven't owned the unit that long, and the coil
could just already be a more resistive coil. I'll let you all know what I
find out.

Well, off to resume loading. A neighbor has just called and offered his lift
truck as a backup.

RJ

--
"Have no one say it, and say it to your shame, that all was well here, until
YOU came."




"Karl Townsend" wrote in message
anews.com...
You might use a new approach. Put in retrofit electronic points and

change
to a coil without a resistor.

THIS IS SO MUCH BETTER! I live in MN and I've changed all my old tractors
over. Now they all start if the battery can kick it over and I haven't
replaced points in years.

This will cost you about $100. Any autoparts store can order them. I
couldn't find it, but there's an online website to get them cheaper, just
for tractor restore.

Karl





  #7   Report Post  
Randal O'Brian
 
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Default

Check your plug wires.

Randy



"Backlash" wrote in message
...
Thanks all, for your valuable input. Problem is, right now I'm in the

middle
of loading my entire workshop into a semi trailer I bought, so needed a
quick solution. Wife got a promotion, we're moving, and at the same time,

a
friend bought out my workshop property, so I had to clear that out also. I
think I'll measure the resistance of the coil, and see If I think I can
eliminate the resistor. I haven't owned the unit that long, and the coil
could just already be a more resistive coil. I'll let you all know what I
find out.

Well, off to resume loading. A neighbor has just called and offered his

lift
truck as a backup.

RJ

--
"Have no one say it, and say it to your shame, that all was well here,

until
YOU came."




"Karl Townsend" wrote in message
anews.com...
You might use a new approach. Put in retrofit electronic points and

change
to a coil without a resistor.

THIS IS SO MUCH BETTER! I live in MN and I've changed all my old

tractors
over. Now they all start if the battery can kick it over and I haven't
replaced points in years.

This will cost you about $100. Any autoparts store can order them. I
couldn't find it, but there's an online website to get them cheaper,

just
for tractor restore.

Karl







  #8   Report Post  
Kevin Beitz
 
Posts: n/a
Default

I had the same problem with my old 1965 International Scout... I put a
super hot yellow racing coil in place of the old one years ago... Its
been working great .......
  #9   Report Post  
Richard W.
 
Posts: n/a
Default


"Backlash" wrote in message
...
Thanks all, for your valuable input. Problem is, right now I'm in the

middle
of loading my entire workshop into a semi trailer I bought, so needed a
quick solution. Wife got a promotion, we're moving, and at the same time,

a
friend bought out my workshop property, so I had to clear that out also. I
think I'll measure the resistance of the coil, and see If I think I can
eliminate the resistor. I haven't owned the unit that long, and the coil
could just already be a more resistive coil. I'll let you all know what I
find out.

Well, off to resume loading. A neighbor has just called and offered his

lift
truck as a backup.

RJ

--
"Have no one say it, and say it to your shame, that all was well here,

until
YOU came."




"Karl Townsend" wrote in message
anews.com...
You might use a new approach. Put in retrofit electronic points and

change
to a coil without a resistor.

THIS IS SO MUCH BETTER! I live in MN and I've changed all my old

tractors
over. Now they all start if the battery can kick it over and I haven't
replaced points in years.

This will cost you about $100. Any autoparts store can order them. I
couldn't find it, but there's an online website to get them cheaper,

just
for tractor restore.

Karl


Most engines run with a 6 volt coil.The resistor is to bring the voltage
down from 12 volts to six volts. Fords use a resistor wire. Chryslers use a
ballast resistor. I don't recall what GM uses. When you start the engine the
system by passes the resistor so you are running 12 volts to the coil. This
is for cold weather starting. Once the engine is running the power is
rerouted through the resistor and you are then running the coil with the
proper 6 volts. Some cars use coils with the resistor built in.

Richard W.


  #10   Report Post  
 
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On Sun, 5 Dec 2004 07:09:57 -0500, "Backlash"
wrote:

My forklift has the older, cylindrical shaped ignition coil, with a 12 volt
system. The coil was using an external resistor when I got the lift truck.
It is now wired to get 12 volts when starting, and it fires up INSTANTLY. It
then drops back to the resistor for running. However, after starting the
engine with half choke and running for a couple of minutes, I push off the
manual choke. As the engine warms up, you can hear cylinders "coming in"
that weren't running properly before. A plug check found smutty plugs, but
the engine runs relatively well after the "clearing out" occurs. The engine
should not be over-choked, because I am just choking it enough to keep it
running as well as possible, no black smoke exhausting, etc. I am wondering
if the resistor is cutting back on the coil too much, affecting my spark
after startup and during running. The coil has no markings. I am thinking
about bypassing the resistor to see if things improve, but I obviously don't
want to burn up the coil. Does anyone have any info on how to tell if a coil
really NEEDS an external resistor? Any ohm readings I can take to tell if
it's a coil that can be run without a resistor at 12 volts?
Thanks for any helpful info.

RJ

Check the coil primary resistance. If it is3.25 ohms, run without
resistor. If less than 3.25 ohms, total of resistor and coil should be
roughly 3.25.


  #11   Report Post  
 
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On Sun, 5 Dec 2004 17:06:37 -0800, "Richard W."
wrote:


Most engines run with a 6 volt coil.The resistor is to bring the voltage
down from 12 volts to six volts. Fords use a resistor wire. Chryslers use a
ballast resistor. I don't recall what GM uses. When you start the engine the
system by passes the resistor so you are running 12 volts to the coil. This
is for cold weather starting. Once the engine is running the power is
rerouted through the resistor and you are then running the coil with the
proper 6 volts. Some cars use coils with the resistor built in.

Richard W.


Not true. Coils on 12 volt systems with resistors generally run on
closer to 8 volts.
6 volt coils are generally 1.14-1.26 ohms.
12 volt coils used wqith a resistor are generally 1.42-1.58 ohms. They
range from 1.25 to 1.73
12 volt coils for use without a resistor generally run 3.15 to 3.48
ohms, while electronic ignition coils, particularly CDI, generally run
well under 1 ohm, with 0.3 to 0.6 being common.
  #12   Report Post  
 
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Take out the resistor. It will run fine. One caveat. Make sure that
you do not leave the key on without the engine running. It WILL blow
up the coil. Running the higher voltage will give you a "hotter"
spark.

My dad, grand dad and I have been putting alternators on IH B and C
tractors for years. Of course all were originally 6V systems. We have
just switched them directly over to 12V using the original coil. As
long as you do not let the coil "soak" at this higher voltage it will
not adversely affect it. I am sure it does reduce the life of the
coil, but we have run then for an awful long time with out replacing
any of them. It isn't actually the voltage that is hard on it, but the
higher current that the primary windings take without the resistor
limiting the current.

As mentioned, this will result in a hotter spark. This is good. You
can run a wider gap and/or get the plugs to jump better if you are
burning oil or have likewise poor conditions.

As one other poster mentioned, you could put another resistor in
parallel to effectively 1/2(assuming matching resistor) your resistance
and bump up the primary voltage. This will work well and limit the
potential to cook the coil.

JW

  #13   Report Post  
 
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Pertronix ( http://www.pertronix.com/ ) is one company that comes to
mind. I live in Karl's neighborhood, and have to agree. A "pointless"
system is so much better. At a $100 a crack, they get pricey if you do
a lot of them, but they really work well. I have installed one on
spray buggy and one in an older car. I think I have the older Ignitor
module.

  #14   Report Post  
 
Posts: n/a
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Pertronix ( http://www.pertronix.com/ ) is one company that comes to
mind. I live in Karl's neighborhood, and have to agree. A "pointless"
system is so much better. At a $100 a crack, they get pricey if you do
a lot of them, but they really work well. I have installed one on
spray buggy and one in an older car. I think I have the older Ignitor
module.

  #15   Report Post  
invntrr
 
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Default

I have a like new MSD 6 that gives you a hot spark ... bought it for my
B3000 but found out my truck has " direct ignition " with no rotor so it
isn't compatable
wrote in message
oups.com...
Take out the resistor. It will run fine. One caveat. Make sure that
you do not leave the key on without the engine running. It WILL blow
up the coil. Running the higher voltage will give you a "hotter"
spark.

My dad, grand dad and I have been putting alternators on IH B and C
tractors for years. Of course all were originally 6V systems. We have
just switched them directly over to 12V using the original coil. As
long as you do not let the coil "soak" at this higher voltage it will
not adversely affect it. I am sure it does reduce the life of the
coil, but we have run then for an awful long time with out replacing
any of them. It isn't actually the voltage that is hard on it, but the
higher current that the primary windings take without the resistor
limiting the current.

As mentioned, this will result in a hotter spark. This is good. You
can run a wider gap and/or get the plugs to jump better if you are
burning oil or have likewise poor conditions.

As one other poster mentioned, you could put another resistor in
parallel to effectively 1/2(assuming matching resistor) your resistance
and bump up the primary voltage. This will work well and limit the
potential to cook the coil.

JW





  #16   Report Post  
 
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Default

On 6 Dec 2004 14:11:10 -0800, wrote:

Take out the resistor. It will run fine. One caveat. Make sure that
you do not leave the key on without the engine running. It WILL blow
up the coil. Running the higher voltage will give you a "hotter"
spark.

My dad, grand dad and I have been putting alternators on IH B and C
tractors for years. Of course all were originally 6V systems. We have
just switched them directly over to 12V using the original coil. As
long as you do not let the coil "soak" at this higher voltage it will
not adversely affect it. I am sure it does reduce the life of the
coil, but we have run then for an awful long time with out replacing
any of them. It isn't actually the voltage that is hard on it, but the
higher current that the primary windings take without the resistor
limiting the current.

As mentioned, this will result in a hotter spark. This is good. You
can run a wider gap and/or get the plugs to jump better if you are
burning oil or have likewise poor conditions.

As one other poster mentioned, you could put another resistor in
parallel to effectively 1/2(assuming matching resistor) your resistance
and bump up the primary voltage. This will work well and limit the
potential to cook the coil.

JW

Coil life may not suffer, but with point ignition, point life WILL.

As for current vs voltage - you can argue both ways. High current can
only flow through a fixed resistance with increased voltage - so which
came first - the chicken or the egg? You cannot have high current
without too high voltage - so it IS the voltage that is critical for a
given coil. The only way a ballast resistor reduces the current flow
in the coil is by reducing the voltage seen across the coil. It does
this by creating a "voltage devider". The resistor drops its share of
the voltage, leaving less for the coil.

The net effect is to reduce the current flow through the entire coil
primary circuit - including the points.
  #17   Report Post  
 
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On Tue, 07 Dec 2004 00:19:05 GMT, "invntrr"
wrote:

I have a like new MSD 6 that gives you a hot spark ... bought it for my
B3000 but found out my truck has " direct ignition " with no rotor so it
isn't compatable

Chances are EXCELLENT that the existing direct ignition system will
out-perform the MSD anyway.

Today's electronic ignition systems are capable of putting out
astronomical spark voltages, at pretty sizeable currents.
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