Super m coil from napa

[756puller]

Got a super m that a guy wants me to get running. It has sat for four years now. I did look at it and determined it's a 12 volt system so I was going to replace the coil and points off the bat. Would I be better off to put a new coil on that's internally resisted or should I put the resister on the coil separately? If i go internally resisted coil does anyone know of a 12 volt napa coil that would work?

[Matt Kirsch]

Save yourself and the guy some money. Coils rarely go bad. Clean the points and they'll almost certainly work just fine. Plus you get to be the "Magic Miracle Man" who got his tractor running with only a new battery and a folded dollar bill.

If you insist, replace the coil with whatever is there now. You may run into some guff asking for an "internally resisted" coil, as there is no such thing. There are 6V coils and 12V coils "for use with external resistor" and 12V coils "no external resistor required." I don't know how you'd ask for one at NAPA without a make, model, and year.

[756puller]

I've had a few coils go bad over the years, I already checked for spark and there isn't any.

[iowaboy1965]

That could just be dirty points tho or bad cap, condenser bad or poorly contacting coil wire. I agree, no reason to replace the coil without some more checking.

[HydroTek]

2 hours ago, 756puller said:

Would I be better off to put a new coil on that's internally resisted or should I put the resister on the coil separately? If i go internally resisted coil does anyone know of a 12 volt napa coil that would work?

There is no such thing as "internally resisted"
Really wish that myth would die a horrible death
... and yes , I know some coils have misinformation printed on the outside

Ya gonna get a 12 volt or a 6 volt ... or slight variations for "high performance" secondary increase

Use your meter and Ohm the primary to determine which you have in hand

[nate]

I’m with most of the others,  I can’t figure out why people are so eager to throw stuff away and use Chinese junk as replacements.  Check and test, probably just needs oxidation cleaned off points. 

[M-MAN]

NAPA  IC14SB is for the coil that doesn't need an external resistor.

Don't know why folks take offense when someone mentions a built in resistor. The terminology doesn't matter since we all know what it means. Truth be told both sides are right. There is no stand alone resistor inside. On the other hand there is the extra rounds of wire inside to increase resistance just like the rounds of wire inside the ballast resistor. 

[HydroTek]

Do you buy light bulbs with a "built in resistor" ?

No ...you get them with the correct voltage rating for the system they are going onto

[catman13]

 

a few cheap checks

clean the points good, check the wire where goes into the distributer, disconnect the kill switch

[supermechanic]

Open the distributor, remove the rotor (and dust shield, if this one has it), bump engine over till the points are closed.

 turn on ignition switch so 12 volts is on the positive side of the coil.

 reach in to the moving arm of the points, wiggle it a bit with your finger.

 You should see some sparks at the points if the coil is good.

 snap open the points a few times, a spark should appear at the points when they open.  

A nice snappy blue spark at least 1/2 inch long should be available at the high tension post on the coil.

If, after doing this action, no sparks are at the points, or at the high tension post, I would then condemn the coil, usually it's just oily crud built up on the points.

[DHF]

grandson says super H won't start i say superH always starts so i go look no spark.  when the few times i have a coil go bad it would start and run until hot then die so i didn't think it was coil. cleaned points with file they look good i had a condenser in my parts box so for fun i changed condenser got spark tractor started right up.  old condenser looked fine.

pete

[supermpuller]

pertronix electronic ignition  and flame thrower coil with internal resister. 40,000 volt  1.5 ohm.  I used that set up om my pulling tractors for years.  I then switched  over all my gas farm tractors, and the all start run better and you never have to change points condenser.

[JaredT]

I did a 12v conversion on our C. Bought the first coil from Napa, it lasted about 12 hours and quit, replacement coil lasted maybe 18 hours. I replaced that one with a Steiner coil, not sure what brand, that lasted maybe 20 hours and quit.  Finally I found and installed a Flamethrower, at least 50 hours on it and still going strong. Napas electronic parts aren't what they used to be. 

[756puller]

Got lucky, I did grab points/condenser/coil just so I could have them while I was out there. Hooked up jumper cables, checked for spark, it has spark so I gave it a shot of either and it fired right up.

[Diesel Doctor]

On 11/13/2024 at 7:46 PM, HydroTek said:

Do you buy light bulbs with a "built in resistor" ?

No ...you get them with the correct voltage rating for the system they are going onto

The last coil I can confirm was dead was on a 1962 Chevy Nova and was over 20 years ago.

It quit on the road, I pulled the coil wire and oil was dripping off it.

That was a clue.

The new NAPA coil had the threads buggered up and was the only one in town.

It got us by.

I have felt coils that were very hot. 12V feeding a 6V coil so it needs the resister. 

I have put Flamethrower, and the like, coils on things and in my estimation, were a waste of money.

I failed to feel that new found power and economy.

 

 

[HydroTek]

26 minutes ago, Diesel Doctor said:

The last coil I can confirm was dead was on a 1962 Chevy Nova and was over 20 years ago.

It quit on the road, I pulled the coil wire and oil was dripping off it.

That was a clue.

The new NAPA coil had the threads buggered up and was the only one in town.

It got us by.

I have felt coils that were very hot. 12V feeding a 6V coil so it needs the resister. 

I have put Flamethrower, and the like, coils on things and in my estimation, were a waste of money.

I failed to feel that new found power and economy.

 

 

Not sure I get the point of your post

The whole "it has an internal resistor" thing is a fallacy , and should be squashed with extreme prejudice

Coils simply do not have a built in resistor inside of the coil to control voltage

Standard ignition coils  are a simple transformer , with the two windings sharing the negative marked terminal

The ratio and gauge of the wires inside determine the input voltage and output voltage

Physical size of the coil housing also plays a part in the amount of "coil" that can be used

Acceptable current draw determines the length and diameter of the primary winding

 

[Diesel Doctor]

23 hours ago, HydroTek said:

Not sure I get the point of your post

The whole "it has an internal resistor" thing is a fallacy , and should be squashed with extreme prejudice

Coils simply do not have a built in resistor inside of the coil to control voltage

Standard ignition coils  are a simple transformer , with the two windings sharing the negative marked terminal

The ratio and gauge of the wires inside determine the input voltage and output voltage

Physical size of the coil housing also plays a part in the amount of "coil" that can be used

Acceptable current draw determines the length and diameter of the primary winding

 

My point was that coils rarely fail when properly installed.

I have seen more incorrectly installed with the wrong voltage and many times. 

You are right, The whole "it has an internal resistor" thing is a fallacy , and should be squashed with extreme prejudice

[Matt Kirsch]

On 11/13/2024 at 8:46 PM, HydroTek said:

Do you buy light bulbs with a "built in resistor" ?

No ...you get them with the correct voltage rating for the system they are going onto

Except that many "12V" coils require an external resistor, because they are really 6V coils.

Go and buy a coil for a late 60's early 70's Mopar. It will be labeled as "12V" even though the car has a ballast resistor for the coil.

At Tractor Supply you can buy a "12V, external resistor required" or a  "12V no external resistor required" coil.

Because, most people's eyes will get wide at being sold a "6V" coil... "Bbbbbutttttt, my car/tractor is 12V. That must be the wrong coil!" It isn't because you have a ballast resistor. "A what resistor? What a line of BS! You are an idiot! I want to see the manager! NOW!"

[England806]

On 11/13/2024 at 9:45 PM, HydroTek said:

There is no such thing as "internally resisted"
Really wish that myth would die a horrible death
... and yes , I know some coils have misinformation printed on the outside

Ya gonna get a 12 volt or a 6 volt ... or slight variations for "high performance" secondary increase

Use your meter and Ohm the primary to determine which you have in hand

Exactly! They have an internal resistance (determined by wire size and length etc) but not an internal “resistor “. Had a friend cut a scrap coil open one day. Looking for an internal resistor. He was disappointed 🤣

[HydroTek]

1 hour ago, England806 said:

Exactly! They have an internal resistance (determined by wire size and length etc) but not an internal “resistor “. Had a friend cut a scrap coil open one day. Looking for an internal resistor. He was disappointed 🤣

I have opened many coils over the years
scrapping the copper

Same for starter solenoids

[HydroTek]

4 hours ago, Matt Kirsch said:

Except that many "12V" coils require an external resistor, because they are really 6V coils.

Go and buy a coil for a late 60's early 70's Mopar. It will be labeled as "12V" even though the car has a ballast resistor for the coil.

At Tractor Supply you can buy a "12V, external resistor required" or a  "12V no external resistor required" coil.

Because, most people's eyes will get wide at being sold a "6V" coil... "Bbbbbutttttt, my car/tractor is 12V. That must be the wrong coil!" It isn't because you have a ballast resistor. "A what resistor? What a line of BS! You are an idiot! I want to see the manager! NOW!"

I am aware of the misinformation on the labeling  of some ignition coils -- that is part of the reason I am so adamant about the whole "internal resistor" fallacy

Mopar was not the only player in this fantasy -- IH was also guilty of printing on the outside of the coils the misinformation

I suppose it was easier for people to believe a lie , than to understand how the ignition system really works -- "external resistor" is a whole another conversation and mostly because people have low reading comprehension

Well ... that is the reason we need warning labels on anti-freeze to not drink it -- and the list goes on

Another one , Kinda like when some get miffed when a Case-IH is called Case

[Jeff-C-IL]

Yeah - many people do not understand this.   A coil is just a transformer - two sets of windings wrapped around a magnetic "Core" - usually steel.   One set is wound with the correct resistance and turns of wire to operate on either 6V or 12V supply depending.  You need the coil to have a certain current flow.  A 12V coil should have more winding and a higher resistance to keep the same amount of current flow in the coil.   The equation is super simple - I = V/R

The secondary coil is wound for a much higher output voltage, to create an arc across the plug gap.    Coils like the Flamethrower were wound for even higher voltages - they could help in engines that ran dirty...ie fouled the plugs.  The ratio of the voltages is set by the ratio of # of windings between the #1 & #2 coils.

What many don't understand is a transformer only works on CHANGING the current flow - it does not work on steady state (DC).   Current flowing in coil 1 creates a magnetic field in the core.  a constant magnetic field will do nothing to coil 2.    CHANGING the current flow is what changes the magnetic field, which then creates a current flow in coil 2.    So just hooking the 12V battery up to it just means you are getting a steady current flow thru coil 1.   There will be no output voltage on coil 2.  its only by turning the current in coil 1 on & off (points) that you get current (spark!) out of coil 2.

Note that hooking the battery up directly will heat up any coil - they are not designed for constant current.

If a 6V coil hooked up to a 12V system - use the equation.   You will get 2x the current flow, (which means a much higher output on #2 - which can be good) - but also means you are dumping way more power thru the coil.  Equation is also simple - P=VI.  More power = more heat.  

[Matt Kirsch]

57 minutes ago, HydroTek said:

I suppose it was easier for people to believe a lie

Nothing unusual about that, but it sure seems like an awful strange hill to choose to die on...

[HydroTek]

You shall not pass ...LoL

[DT Fan]

6 volt coil 1.5 ohms. 12 volt 3 ohms?