NAPA ic14sp coil

If I were to replace my 12 volt coil with an ic14sp do I just bypass the resistor? Can I just solder that wire at that point and forget it? Exactly what have I to gain other than eliminating the resistor? Im not a doubter, just want to know.

The part number should be IC-14SB. You will not need the ballast resistor, so you can solder the two ends together or run a new wire. The gain will be a better and more reliable spark.

There's nothing to be gained by replacing your coil. Your tractor will run just as good as it does now. No better, no worse.

I removed my post.
The advice given since, is better.

You gain nothing by eliminating the resistor, when it comes to cold-starting performance. You lose, you don't gain.

If you want simplicity and don't care about the rest, then yes - bypassing/eliminating the resistor is fine, along with using something like the NAPA Chinese IC14SB coil.

Why do you suppose that the only American car ever sold in the 60s and 70s that did NOT use a resistor was American Motors? Why do you suppose that Ford, Chrysler, and General Motors DID use coil-resistor bypass system?

Do you suppose that the AM brand was known for being superior to all the other makes? If so, I suspect you were not working as a mechanic back when they were current.

When it comes to a breaker-point system, nothing is going to surpass reliablity and cold-starting max-voltage then a coventional coil with external resistor and some sort of cold-start bypass.

Buying a coil with high ohm primaries that does not need an external resistor is an inferior compromise for people who just want simplicity. Same sort of deal as choosing a one-wire alternator, except the latter works better.

You can buy a new non-resistor coil for $8 or $10 and a resistor for $6. Not exactly a huge expense. If you have a Delco starter, you might already have a built in bypass. If not, you can add a $10 relay to do it. Or, a heat-adjusting resistor like many Ford tractors use.

A conventional new coil for $8 to $10, and a new resistor for $6 is not twice the cost of an IC14SB that costs $19. And if some poor sucker buys a NAPA IC14 instead, it costs $44 instead of the $19 the Chinese IC14SB costs.

Also, winding are windings, regardless if inside a coil's tin can, or outside as in a ballast resistor. They can all fail, at some point in time. Wire wound resistors often last a very long time. So do carbon-resistor wires like GM used back in the points-days.

The external resistor and bypass system used with the correct coil can give much high max. voltate that the "all in one tin can" deal.

No. Less max spark potential and no change in reliabilty when comparing one properly done system to the other.

A tractor needs at the least 15,000 volts to run, 20,000 volts for cold starting, but 30,000 max. volts is usually the absolute minimum used in OEM tractor battery-igntion 12 volt systems.

NAPA Chinese MBE IC14SB gives a max. of 30,000 volts.
Most OEM 12 volt tractors use a coil, external resistor, and bypass system that give a max. of 40,000 - 50,000 volts. Some as high as 60,000 volts.

Please explain the "gain in performance" you mention.

(quoted from post at 10:11:50 04/05/10) You gain nothing by eliminating the resistor, when it comes to cold-starting performance. You lose, you don't gain.

If you want simplicity and don't care about the rest, then yes - bypassing/eliminating the resistor is fine, along with using something like the NAPA Chinese IC14SB coil.

Why do you suppose that the only American car ever sold in the 60s and 70s that did NOT use a resistor was American Motors? Why do you suppose that Ford, Chrysler, and General Motors DID use coil-resistor bypass system?

Do you suppose that the AM brand was known for being superior to all the other makes? If so, I suspect you were not working as a mechanic back when they were current.

When it comes to a breaker-point system, nothing is going to surpass reliablity and cold-starting max-voltage then a coventional coil with external resistor and some sort of cold-start bypass.

Buying a coil with high ohm primaries that does not need an external resistor is an inferior compromise for people who just want simplicity. Same sort of deal as choosing a one-wire alternator, except the latter works better.

You can buy a new non-resistor coil for $8 or $10 and a resistor for $6. Not exactly a huge expense. If you have a Delco starter, you might already have a built in bypass. If not, you can add a $10 relay to do it. Or, a heat-adjusting resistor like many Ford tractors use.

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JDemaris, sometimes I like the way you think. I have posted this before, but it aligns well enough with your position that I now post it again.

Ballast resistor your friend.

I will make this as simple as possible. First, you need to understand that Power is equal to heat (1 watt = 3.4 BTU), and that throughout the industry, coil currents are about 4amps, give or take a small amount, whether 6v or 12v, ballast or not. Next, Power = I X I X R = I*2 X R (that is current squared times the resistance or current times current times resistance). Your 9N, according to the Dealer Service Training Manual had a coil with a primary resistance of 0.47 to 0.51 ohms, running at 4.8amps.
P= 4.8*2 x (0.5 ohms) = 11.25Watts

Now, let us adjust the coils primary resistance such that we maintain the 4.8amps, but WITHOUT the need for a ballast resistor:

This 'new' coil will have 1.27 ohms primary resistance. What is the power (heat) put into it?
P = 4.8*2 X (1.27 ohms) = 29.28 Watts. WOW! You say. Almost a factor of 3X!

You ain't seen nothing yet, my friend.

Now, let us move up to a "true 12v coil", such as the NAPA IC-14SB, a 3.25 ohm primary coil.
Maintaining the 4.8amps, P = 4.8*2 X (3.25 ohms) = 74.88Watts. Holy, stuff! You say.

Well, in reality, if your mighty fine charging system is keeping your battery at the specified 14.4volts. the current will be 14.4/3.25 = 4.4amps and the power will ONLY be P =4.4*2 X (3.25 ohms) = 64Watts. What a relief! Only 6X the old Ford number.

Apparently the heat conducting oil filled metal (also heat conducting) can IC-14sb can live with this power level. Don't feel of it long!

But, what if we had stuck with the original Ford 6v, 0.5 ohm coil AND added 2.5 ohms ballast, which is the value necessary to maintain the original 4.8amp coil current when operated on 14.4 volts? What would the coil power be now? P = 4.8*2 X (0.5 ohms) = 11.25Watts. Well, now, "ain't that amazing", just like Ford designed it!

Where did all that extra power go? It went into the 2.5 ohm resistor (outside of the coil, not in it) and the amount that the coil now does not have to dissipate is, P = 4.8*2 X (2.5 ohms) = 57.6 Watts. The total is 68.85, but the coil is only burdened with 11.25W, just as Henry intended. Needs a hefty resistor though.

Now, before everyone goes all ga ga, all those power levels apply only under the conditions where you stall the engine and leave the key on, points closed. When up and running ALL those power levels can be divided by approximately 3*2, due to dwell time combined with the L/R exponential charging curve of the system. BUT the relative ratios (comparisons) still hold, as in the original 11.25/3*2 = 1.25W compared to the IC-14sb, 64/3*2 = 7.1W...still about a 6X ratio.

Need more of 'why the ballast resistor is your friend'?

The IC-14sb's copper windings will increase in resistance from 3.25 ohms at room temperature to 4.33 ohms at 200F. That causes coil current to fall to 3.33amps, from the 4.4amps. A decrease of 25%. Since Energy output of coil is proportional to current squared, that means that energy delivered to the plugs decreased by a whopping 44% !!

The friend to the rescue! the original Ford 6v, 0.5 ohm coil's resistance over the same temperature change goes up from 0.5 to 0.665 ohms, but it has a fixed 2.5 ohm external ballast resistor in series with it, so the total R at room temp is (0.5 +2.5) = 3 ohms & current as we already know is 14.4/3 = 4.8amps. Then at 200F, the total R is (0.665 + 2.5) =3.165 ohms, & current is 4.55amps. A decrease of 5.2% (compare to 25% above, with no ballast res). AND the Energy...now down by 10% (compare with 44% loss above without ballast res).

The ballast resistor moves heat out of the coil AND it dilutes the increase of coil resistance change with temperature, such as to provide a more constant current and a more nearly constant energy over the temperature range.

Mind you, that those percentages hold when running, i.e., the 44% and 10% values do NOT get divided by 3.

The so called 12v, 2.5 ohm square can plastic coil is in the middle of all this, but it is perfectly clear that it's resistance increase from 0.5 ohm original to 2.5 ohms will increase the power (heat into it) by a factor of 2.5/0.5 = 5X at 4.8amps, even though it does use a small ballast resistor. That is P = 5 X 11.25W = 56.52W (stalled) or ~ 6.28W (running). All still 5 times the original Ford.

Why are these made & sold? I do not have a clue, beyond the idea that an individual doesn't have to determine the needed ballast resistor value and it sells.
Do they work & hold up? Again, no real clue. How many are out there running successfully for a long time? One thing appears fairly certain & that is that most recommendations call for reducing the current to about 3 to 4 amps, which should make them live a little longer, albeit at lower energy output and all the problems that may come with that in starting, running, etc.
{This would be putting about the same power into coil as a 1.5 ohm, 6v, with no ballast res or approximately 3.6W or 3.6/1.25=2.9 times original design heat}

Why did I put this together? It is clearly among the highest problem/question area on the boards & thus not the best understood. So, it is here that I hope you will at least go into whatever you do with as much information as you can obtain. Further, it may shed some light on why these conversions result in so much board traffic. 3 to 5 times original stress levels is notable. But you don't have to suffer that.

(quoted from post at 07:11:50 04/05/10)
Why do you suppose that the only American car ever sold in the 60s and 70s that did NOT use a resistor was American Motors? Why do you suppose that Ford, Chrysler, and General Motors DID use coil-resistor bypass system?

When it comes to a breaker-point system, nothing is going to surpass reliablity and cold-starting max-voltage then a coventional coil with external resistor and some sort of cold-start bypass.

Click to expand...

The only reason all the auto makers in the 60s and 70s used a external resistor is so they could use a cold start bypass system.
The only problem with applying that thinking to these old tractors is the starter relay is not a type that will allow a cold start bypass setup.

So basically you are comparing apples to oranges to try and prove your point.

Does not the external resistor have a positive temperature coeficient? I was not aware that it was a constant R device.

Hello John , The point was that American Motors cars did not start well in the Cold and Gm, Ford and Chyrsler did . Well when you are converting from 6 volt to 12 volt you have to install a new starter solenoid any ways so just install one for a cold start bypass and kill two birds with one stone . I have posted the jeep one I have been using for 25 years up here in the cold Northeast on this board 83 times and I guess no one has paid attention to it . It is a perfect bolt on just add the bypass wire and you do not even have to modify the original wiring harness . I even listed it in a story written for the 9N-2N-8N-NAA NEWSLETTER 15 years ago . And I bet you would like the Part Number wouldn't you ? Thanks Tony

Hello Tony;
Jeep makes a ground isolated relay so I can keep my orginal starter button that also has a cold start bypass?????????????

If you have posted such a relay in the past I have missed that.

All the relays I know of that allow a cold start bypass are grounded by the mounting bolts so they do not work on these old Ford Tractors.

Depends on what specific resistor you use. They are not all the same. Resistors made as "ballast" resistors are thermally-reactive.

GM uses a carbon wire resistor that I believe supplies a constant fixed resistance.

Apples to oranges? It certainly is not. Tractor companies have just about always relied on automotive technology for their systems.

Not all coil and resistor systems use a relay- bypass as you state. Many use a thermally reactive ballast resistor (like my Ford 4000 has).

Many tractors uses a coil and resistor system just fine without relying on a starter relay for bypass. Ford uses the heat-sensitive resistor. Deere used a bypass built into the ignition switch. Some companies used a manual bypass switch.

The tractor companies that opted to use Delco-Remy starters usually DID opt to use the starter solenoid for bypass since it was already there (the R terminal).

It's never been a big secret that a tractor with a 12 volt system never had 12 volts available to the coil when cranking, no matter how you hook it up. When cranking, system voltage drops down to 9 or 10 volts. That's why the best systems use, in 12 volt systems, a 6 volt type coil along with a resistor. A coil meant to work on 12 volts, that never gets more then 9-10 volts when cranking, does not work very well.

When it comes to cars, most auto makers knew that. A 6 volt system drops to 4-4.5 volts when cranking, and a 12 volt system drops to 9-10 when cranking. Thus a 12 volt starter and a 12 volt igntion is usually designed to operate well at 9 volts - NOT 12 volts.

Why can't you use the grounding-type relay? As long as you buy an older type that does not have a diode in the coil system, it will work with any polarity. Common on older 60s-70s Jeeps, Ford cars and trucks, etc. I buy them new for $8 each.
Hook positive or negative to the "S" terminal, and coil bypass to the "R" terminal. They are sold in 6 volt and 12 volt versions. Later ones used on Fords incorporate a diode and only work on negative ground.

There are also many cheap relays for under $10 that are two sets of isolated contacts and no ground. Very easy to hook into any tractor for a resistor bypass.

I'll ask a question for all of you.
To create a bypass circuit, could you add a wire from the starter lug of the solenoid to the coil? This wire would NOT go through the ballast resister.
This would be on a 12 volt converted Ford tractor like my 1964 Ford 4000.

Now I have the solenoid wired with the battery wire in on top with the wire from the alternator and another wire to the hot side of the key switch
The bottom lug just has the starter wire on it. The "I" lug I have the wire from the keyed side of the switch. The S lug is wired to the grounding switch on the Trans cover.
The coil is wired from the keyed side of the switch through a ballast resister.
I have not done this. I was just wondering.
Keith

(quoted from post at 11:01:47 04/06/10) I'll ask a question for all of you.
To create a bypass circuit, could you add a wire from the starter lug of the solenoid to the coil? This wire would NOT go through the ballast resister.
This would be on a 12 volt converted Ford tractor like my 1964 Ford 4000.

Now I have the solenoid wired with the battery wire in on top with the wire from the alternator and another wire to the hot side of the key switch
The bottom lug just has the starter wire on it. The "I" lug I have the wire from the keyed side of the switch. The S lug is wired to the grounding switch on the Trans cover.
The coil is wired from the keyed side of the switch through a ballast resister.
I have not done this. I was just wondering.
Keith

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on't work. Reason is that while it would supply full voltage to coil, during start, once start is over, the starter terminal will look like ground (starter internal resistance is very, very low) and thus virtually short your coil supply to ground. Now, you might place a diode in such connection & gain some starting benefit & essentially break that connection once start is over.

Hello John , Napa part number ST-83 (that why I said 83 times in the last post, just a joke)is the one I have been using for years . But ALL of my 12 volt conversions use the original 12 volt Diesel generator, original wiring harness and then the ST-83, 12 volt coil(with a Napa ICR11 resistor or a resistor coil, like the Pertronics High Voltage one used with the Electronic Ignition kits which is what I use all of the time too), bulbs etc. etc.

Hello John , I forgot to mention in my last post that Ford used to make a Ballast Resistor for use on their Industrial Engine power units that were gas 134, 173 or 192 that even had a Ford logo stamped on it. On the power units it was mounted on the center bolt of the valley cover just above the coil . Most of my conversion work is for show or restoration tractors that are suppose to look original and I just tape the bypass wire into the harness to hide it , work tractors get what ever the customer wants . Thanks Tony

Tony, just to be 'perfectly clear' (as someone used to say), is this drawing on the left an accurate representation of your ST-83?

While I don"t necessarily disagree with the benefits about the a switchable ballast resistor primary igniton ciruit possibly being superior to a fixed ballast resistance primary circuit from the standpoint of providing a higher primary current during start and less heat input into the coil at normal running conditions, the magnitude of the benefits are dependent on the relative resistance of the resistive elements at start up and in operation.

On the con side, the ignition circuit become a bit more complicated for this system and requires the addition of more components into the primary circuit especially for some of the early model tractors While the components to do this are generally very relable, the overall system reliability will decrease somewhat with the addition of more componetns and their associated connections.

So what is the gain of the switchable ballast resistance over the fixed internal resistance system? If the coil is designed for the higher heat dissipation, there"s no loss in reliability from the built in resistance and the system is more reliable with few parts and connections. The switchable ballast resistance system adds better starting capability with added complexity and cost and less reliability, albiet most likely acceptable reliability.

The always cost concious automotive industry went to the switchable ballst system most likely driven by emmision regulations in the mid 60"s I believe.

Seems like about a wash to me. None the less, an interesting discussion. Opinions are like belly buttons;everybodies got one.

(quoted from post at 14:48:28 04/06/10) While I don"t necessarily disagree with the benefits about the a switchable ballast resistor primary igniton ciruit possibly being superior to a fixed ballast resistance primary circuit from the standpoint of providing a higher primary current during start and less heat input into the coil at normal running conditions, the magnitude of the benefits are dependent on the relative resistance of the resistive elements at start up and in operation.

On the con side, the ignition circuit become a bit more complicated for this system and requires the addition of more components into the primary circuit especially for some of the early model tractors While the components to do this are generally very relable, the overall system reliability will decrease somewhat with the addition of more componetns and their associated connections.

So what is the gain of the switchable ballast resistance over the fixed internal resistance system? If the coil is designed for the higher heat dissipation, there"s no loss in reliability from the built in resistance and the system is more reliable with few parts and connections. The switchable ballast resistance system adds better starting capability with added complexity and cost and less reliability, albiet most likely acceptable reliability.

The always cost concious automotive industry went to the switchable ballst system most likely driven by emmision regulations in the mid 60"s I believe.

Seems like about a wash to me. None the less, an interesting discussion. Opinions are like belly buttons;everybodies got one.

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The main benefit is that it compensates for the low cranking voltage of the battery........when a 12v battery has 9v due to cold & 150A starter draw, the resistance bypass still lets the coil see 9v. Then when running, and resistance in circuit, the coil still sees 9v (not being over-currented /over-heated by 12 to 15v.
Delco started using the ballast switching in the 1950's.....long before the word 'emissions' became a large part of the automotive vocabulary. At the same time, Delco competitor, Autolite, took another approach to the same problem........actually the same method used on the early Ford "N" tractors. That is the temperature dependent ballast resistor. When cold (at starting) resistance is low (~0.4 ohms) and after running a bit, it heats up (when glowing red hot ~1.7 + ohms) thus performing a similar function of compensating for low battery voltage during start up.
Personally, I don't add those kind of mods to my tractors, because they all start just fine as they stand. But if a fellow wants to play, there is a big playground & many options.

Jeep was just one of several companies that used that particular type of solenoid (or call it a relay). Jeep didn't make them, just used them. American Motors used them on many cars. Also, many boats used them, especially Chris Craft.

There is nothing special about the ST83 that Echin makes and markets through NAPA. Just happens to NOT hook one-end of the pull-in coil to ground. Makes no difference if you use this type, or many others on tractors. That pull-in winding has no polarity needs, no more than a starter does. So, if it does require ground, it works them, regardless of negative or postitive ground.

Some automobile companies have been using ballast resistors since the late 1920s. It's not something new. Some older coils had them mounted right on top of the coil and some were inside the can. Some old bypass methods had it built into the push-button starter switch.

I must be missing something. Why can't you use a grounded-coil type relay on your Ford tractor? Polarity doesn't matter.

You can't use a post that feeds the starter when cranking, to also feed power to the coil, UNLESS you hook a diode inline. There would be a backfeed problem once the engine was running.
If you hooked in a diode, it would have to be heavy enough to carry coil current. You can buy them at Radio Shack for a few bucks. But, you could buy a relay with a bypass for near the same price.

Radio Shack stocks a 1N5402 diode that is power rated at 3 amps. It costs $l.60. You can take two, hooked in parallel, to hook the starter post to the coil and it can carry up to 6 amps which will be fine (if your coil is OK). Make sure the diodes are pointing the correct direction. This allows power to travel FROM the starter post TO the coil, but never back.


I don't know what specific starter relay you are using. There are over 40 types of four-terminal relays that all look the same, at a glance.

If you have the type with two larger terminals, and two small terminals marked "I" and "S", it goes like this. One big terminal is hooked to battery power all the time. The other big terminal is hooked to the starter's big post.
With the two small terminals, "S" goes to your starter key switch or push-button switch. "I" goes to the power-primary terminal on the coil.

You can buy a new one from Standard SS581 or NAPA ST81SB, or Delco C3912. New prices is $8 to $10, depending on who you buy from.

I don't tend to buy starter relays by their looks or what car they were used on. I got right to the spec book and buy by the specs they are listing with. Otherwise, things can get confusing since they all look similar.

(quoted from post at 15:22:11 04/06/10) I must be missing something. Why can't you use a grounded-coil type relay on your Ford tractor? Polarity doesn't matter.

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The Ford 8N uses a solenoid/relay wired with one end of coil internally tied to the BATT side of same and the other coil end wired to the small screw/3rd terminal (#1 in first image), which when grounded, causes current thru coil. The transmission mounted neutral safety start switch has only one wire/terminal on it and activation grounds that terminal. That is why you can't use a solenoid that has coil internally grounded to case/mounting (#2). {A note on "can't: anything is possible..I can & have made same work, but some call my work a presidential solution.}
Now........the reason for my questioning & drawing (ST-83) was/is, it seems to be wires like the Ford N solenoid, BUT with the addition of a 4th terminal to be used to essentially bypass the ballast resistor. I have seen at least 4 different solenoids (different internal wiring), but never like what I drew for the ST-83, so I was questioning, whether such an animal actually exist (wired as drawn)?? Typical ballast bypass as on many GM cars is as shown on right side of second image.
Some that I know exist:

I think you're going to have one hell of a migrane before you get your message sunk in on this subject...
I gave up a long time ago.

Rod

[b:d48e259e5e]Personally, I don't add those kind of mods to my tractors, because they all start just fine as they stand.[/b:d48e259e5e] But if a fellow wants to play, there is a big playground & many options.[/quote]

My point, exactly! Why add all the additional stuff to make this system work? If it's there as an OEM system then I'd certainly use it.

I'd sooner go to electronic ignition before I modified the existing system with a switchable ballast resistor, but that's just my personal preference.

Aren't you sorry you asked, now?

Point well taken! oOe of these days I"ll learn to shut up!

Hey JMOR , Some how my post ended up at the top of page one , instead of here . Thanks Tony

Hello JMOR , Why do you keep referring to the 9N/8N 6 volt system when the tractor is a 801/4000 6 volt system that been changed to 12 volts ? One is type A one is type B , Wiring is different between the two of them . There is no common parts bewteen the two of them except for the key switch . Thanks Tony

Hello John , Give me a call at my shop when you a minute 1-413-267-5087 . Thanks Tony

(quoted from post at 00:15:04 04/07/10) Hello JMOR , Why do you keep referring to the 9N/8N 6 volt system when the tractor is a 801/4000 6 volt system that been changed to 12 volts ? One is type A one is type B , Wiring is different between the two of them . There is no common parts bewteen the two of them except for the key switch . Thanks Tony

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hy? I don't reckon I know, Tony. This thread is about 30 or 40 entries long & the opening poster, Jimmyjack, never said what tractor he had. Along the way, no mention was made in the majority of posts as to which tractor, but finally I see 4000 thrown in with the direct wire from starter to coil. I see that this non-specificity is the cause of most of the confusion, as each poster has perhaps a different tractor in his mind!
I see where your discussion is a good fit for such as 4000 diesel & some hundred series where the solenoid receives power from the key switch and ground from a safety switch AND that since it has coil isolated on both ends that makes it "universal" for just about any application. Thanks.