Smoking Coil

[charles germer]

there was 2 types of coils in cars in both 6 and 12 volt systems, internal resistor or external, i worked on a 33 ford woody wagon last year even back than under the dash ford had a resistor to drop the coil input to 4 volts

 

[mfrade]

When auto makers went to 12 volt batteries, they didn't change the ignition system except to add resistors as this supplied a more consistant voltage to the ignition when compared to the old standard 6 volt battery system, Mopar used a "block resistor", single at first then dual, Ford used a resistance wire after the ignition switch to the coil, And GM used both resistance wires or internal resistors inside the coil. Colton, you don't say how much voltage is actually making it into that coil, bad connections or weak wires could also be limiting the actual voltage going into it. Also the condensor could be weak and slowing the flow to ground, so maybe it'll run forever! And - at least around me - there are no warranties on electrical parts. But maybe NC is different. Keep it going in any event!

 

[Greg Riutzel]

The main thing to keep a coil a long time and cool is keeping the primary current within an acceptable range for long point life. Usually we read it's 1-2 amps, but single cylinder it can be as high as 3-4 but no more. Current can be a function of circuit resistance, coil resistance, or both as well as engine speed/dwell time. I didn't say dwell angle, that won't change but dwell time does. In an inductive system, i.e. before CD for example, the main ways to limit current was either coil resistance or a resistance in the circuit. This is where a ballast resistor comes in and it's a "ballast" because it's value will change with current/temperature while maintaining a limit on current but never too much to reduce coil secondary voltage. At idle it can heat up and increase resistance because of long dwell times, but at cruise it can cool off a bit and reduce resistance with a bit more current for charging a coil with a shorter dwell time at the higher RPM. Dwell angle and voltage can be coil killers for an incorrect coil. A coil's voltage rating is closely related to winding construction and turns ratio and resistance is part of that. For dwell angle; 8 cylinder engines, dwell is around 28-32 degrees, 6 cyl. 48-52* and 4 cylinder about 58-61* and this is why most coils for 4 and 6 cylinder engines have coils with at least 3 ohms resistance and 8 cylinder engine coils can range from .85 to 1.8 depending on primary circuit resistance. What about our 1 cylinder engines? Ignition cycle time is once every 360 degrees or once every 2 engine revolutions. Allowing for cam action on the points, that can push Dwell angle into the 180 to 210 degrees! That's an incredible amount of time the points are closed compared to automotive, and a long long time for primary current flow. However with operating speeds in the 3,600 RPM range, the comparatively shorter dwell time can offset the wide dwell angle for actual time the points are closed and a coil with a minimum 3-4 ohm primary resistance can keep primary current below 4 amps and not overheat. The correct coil will also have a beefy construction for the "severe" duty of single cylinder vibrations and whatever the machine the engine is on can throw as well. This a good reason why automotive coils may not go the distance even if they have 3 ohms primary resistance.

 

[charles germer]

simple answer is our prized tractors use a coil with internal balists . what cars and trucks use is of zero help to a layman asking a forum for help. as he or she may have zero idea of what we are talking about with tech talk

 

[Greg Riutzel]

with tech talk

What ya want? A basic understanding of inductive ignition common to all multi or single cylinder or just "get the factory" part? A bit of "tech" gives an answer on why some have replacements that fail, and others go the distance. If this is above your pay grade or reading level, stick with a "factory" replacement.

a coil with internal balists

They don't exist. Show me. Unfortunately, even a Hemmings contributor repeats the myth.

Most repair manuals only give go/no-go tests. If the test light lights, good coil, if not, replace. It's all predicated on factory parts. But if you know the fundamentals, you can separate the good from the super duper "hot" coil hype and know why Kirk's Bosch coils are golden.

 

[charles germer]

https://www.counterman.com/coil-confusion/internal resistor wires directly to a 12 volts source external uses a external resistor or resistor wire between the keyed 12 volt and the coil.

 

[jdrong]

I wonder if anyone is confusing a coil mounted condenser with the legendary "external resistor" that may have never been used on Cub Cadets?

 

[charles germer]

i think you are correct, there were many radio suppressors on coils that looked like a condenser to reduce the spark noise that early fm radios would pick up,

 

[PACub100]

You guys talking Ohms, amps, dwell, resistors, condensers, flux capacitors... I'm just munching on my popcorn, nodding in approval and trusting my Kirk's Transdensor and Bosch Blue to do whatever it is they do to make my tractor go "putt putt"...

 

[gary noblit]

You guys talking Ohms, amps, dwell, resistors, condensers, flux capacitors... I'm just munching on my popcorn, nodding in approval and trusting my Kirk's Transdensor and Bosch Blue to do whatever it is they do to make my tractor go "putt putt"...

Pac,I like reading the tech but don't absorb much..Nice to know somebody understands it..My brain just gets fuzzy..

 

[charles germer]

You guys talking Ohms, amps, dwell, resistors, condensers, flux capacitors... I'm just munching on my popcorn, nodding in approval and trusting my Kirk's Transdensor and Bosch Blue to do whatever it is they do to make my tractor go "putt putt"...

daves ignition items are of the best match for super fire

 

[jdrong]

My question at this point now is, did CC ever sell a GT with an external resistor?

 

[mfrade]

My question at this point now is, did CC ever sell a GT with an external resistor?

At this point in time, does it really matter? If you have a coil and it says to use an external resistor, and you have a points ignition.. then use an external resistor! Save yourself a bunch of headaches and grief... or call Dave Kirk for one of his setups!