'72 IH 140 hot coil UPDATE 3 - w/ DATA


I posted the last 3 days about a recurring hot coil issue on a '72 IH 140. It is 12 V neg ground with 10SI alternator and Pertronix electronic ignition. Tractor runs great for 30 min to one hour then spits, sputters, and cuts off. It won't crank back up. I notice the coil is red hot (and I’ve installed new coils several times included the Pertronix recommended coisl and an ic14SB coil from Napa) when this happens and the ammeter shows a large current drain. I switch the key off and after things cool for around 30 min it cranks up, all seems normal, and things repeat. The alternator was just replaced and the output remains steady at 14.6 V.
Yesterday I installed a 1.6 OHM ceramic encased ballast resistor in the wire from the ignition switch to the + coil terminal per several posters suggestions. This dropped the voltage to the coil from 11.5 V to 8.5 V (measuring from the + coil terminal to the frame). The current must be 3/1.6 = 1.9 amps. I hooked the red wire from the ignition module to the coil input terminal (+) instead of the ballast resistor input terminal as the Pertronix instructions say. Pertronix assumes if a ballast resistor is in place, you probably have a 6 V coil. I use 12 V “no resistor required” coils with resistances anywhere from 3.1 to 3.4 ohms.
Today I mowed for over an hour and had no ignition problems at all. The coil was warm but I could hold my hand on it with no problems (before it could burn you if held for > 3 sec). It looks like a red hot coil somehow causes problems in the Pertronix ignitor ignition module. The Pertronix rep says the hot coil is normal, it’s just coincidental, and the problem is elsewhere. I disagree.
 
100% the hot coil is causing the tractor to sputter and stop. When coils overheat they won't take a charge and stop producing spark.

The question is: Why is the coil getting hot without a ballast resistor?

It must have something to do with the Pertronix ignition. That's the only thing out of the ordinary here. There's no way you got that many bad coils in a row.

Of course Pertronix will not admit to anything... "Oh well gosh golly gee, we've never seen anything like that before..." Yeah, and I was born on Saturn and raised by moon men.

I suspect that suspect the coil would not overheat with the proper 12V supply to the coil and a points ignition.

Why do people insist on these Pertronix ignitions? They are JUNK if you ask me. Nothing but problems. If you look at them funny they burn out something. Don't do the exact right voodoo dance, and they burn out something.
 
Funny thing is that without the EI "improvement' and with a good set of points installed, the tractor could have been used for 10 to 20 years with no drama. But what fun would THAT be???
 
Thanks for posting what you found for a fix. That way we all can learn from it.
With the correct coil for the voltage, about all that is left is that the Prtronix module keeps the coil powered much longer than necessary for the application. Either the wrong module for the application, or a bad one with overly long dwell time.
If you have a chance, connect a dwell meter and post back what 4 cyl dwell reading is and compare that to what normal dwell with contact points would be.
Glad you were able to make a cheap fix using a ballast resistor.
 

I'll not revert back to mechanical points. Messing around setting point gaps and changing condensers is in the past for me. My other 2 tractors have electronic ignitions that I haven't had to fool with since installed about 10 yrs ago. I'll get this thing straightened out. I think they run better with the elc ign than mechanical points. It's just my preference.
 
I agree on EI being a great thing, but there's no comparison between the OEM systems and the finicky aftermarket systems such as the one you have been fighting with, both in spark output and in reliability.
 
I'm wondering about checking the dwell. Does that work with electronic ignition. Never tried it. At any rate, I think there needs to be much better information from the co. that mfg's these kits. Way too much information left out. The one I installed here lately did not even mention the bypass system that is wired up factory during starter engagement.
 

If I'm doing the math right, this modification limits the coil's max output from 40,000 to 30,000 Volts (= 8.5 / 11.5 X 40,000).
The 40,000 V is a key selling point for the Pertronix coil. That sounds nice but it doesn't apply if the tractor stops running.
 
The firing voltage at sparkplugs in a running tractor engine is probably consierably less than 1/4 of 40,000 Volts.

The 40,000 Volts open circuit output voltage of a coil is virtually MEANINGLESS, except for advertising HYPE.

They got YOU, didn't they!
 
(quoted from post at 14:02:50 03/28/15)
Ha! Keep your points, I'll keep my elec ignition modules. My tractors run much better with them and maintenance is zero.
I've been observing this problem from the start. I have reserved comments because "help" from too many directions usually quits being a help. But here is an observation on your most recent post.

You have been fighting with and posting on this problem for 6 days. You have made over 30 posts on the subject. At this point you may have the problem fixed. A one hour run is certainly encouraging, but not yet enough to be proof. For the time and money you have put into this problem, most people could have done a few decades worth of maintenance on a system with mechanical points. Yeah, a tractor may run better on an electronic module, but only if and when it works at all.
 
You are missing my point.

I am NOT against EI, in general.

EI, fuel injection and engine control computers are GREAT, IMHO.

I have installed MANY of the Pertronix units.

My point is that a Pertonix Ignitor ignition (especially the basic Ignitor we are discussing here) is nothing like a OEM or most other aftermarket HEI's or CDI's.

They basically function at the level of a new set of points that doesn't deteriorate over time.

But they ARE a bit funky, occasionally drop dead, and are very sensitive to excessive coil primary current, and accidentally leaving the ignition switch "ON" without the engine running often lets the smoke out of them because they are not "smart" and shut down primary current like many other aftermarket ignition systems and OEM systems do when there's no engine rotation.
 
(quoted from post at 13:08:56 03/28/15) I'm wondering about checking the dwell. Does that work with electronic ignition. Never tried it. At any rate, I think there needs to be much better information from the co. that mfg's these kits. Way too much information left out. The one I installed here lately did not even mention the bypass system that is wired up factory during starter engagement.

It should work. All you are doing is comparing the amount of times the coil circuit is grounded versus the amount of time the coil circuit is open. One you find that ratio you just apply it to to amount of distributor degrees available.

On a four cylinder engine you are working with 90° (360°/4). If the distributor is grounded (points closed) half the time you take .5 (half) and multiply it by 90°. You come up with 45° dwell. The distributor turns 45° with the coil grounded and then the next 45° with the circuit open. It shouldn't make any difference it the coil is grounded by closed points or grounded through a transistor.
 

Good point. I've learned a somethings and the effort will be worthwhile to me when the problem is fixed.

I understand other Pertronix users have had similar problems and perhaps this modification may help someone else.
 
True but the electronic switch ""closes"" the points (Turns on the transistor to ground) much earlier than the points. The points must break far enough to break arcing, and close long enough to saturate the coil. The transistor need not break the arc as it is solid state, and just turns off. The turn on moment is not controlled by cam position, but is delayed just long enough to allow the spark to complete. The more expensive products may delay turn on to mimic points action to allow the coil duty cycly to be ~50%. Jim
 
OK, but, normally one hooks a dwell meter to the distributor side of the coil and other lead to ground. I would imagine one would do it that way also with this electronic system. I would not like frying my dwell meter hooking it up wrong. Like I said before, I think the mfg's of this unit would serve their own purpose better if they would put a little more information on just how this unit should be hooked up and tested for proper operation. Clearly there is a lot of confusion on a lot of peoples part. I understand how solid state circuits function but one cannot tell by looking at them.
 
You will not damage your dwell meter by connecting it to an electronic ignition system, I did it this afternoon.

I dont have anything with a Pertronix system, so I dont have any dwell numbers on it. I do have a 6 cyl 4020 JD that I have fitted with a 70's Chrysler electronic ignition system which I did measure.

I started by checking the point dwell on a 4 cyl tractor with point ignition. The dwell on that one read 34 degrees which I suspect is pretty close to average for a 4 cylinder.

I then checked the 4020 with the chrysler electronic ignition.
The Chrysler ignition module is designed for an 8 cylinder engine running at speeds that may exceed 5000 rpm. It uses a matched Chrysler 1.5 ohm coil and Chrysler dual ballast resistor, so it is all stock matched parts. and has performed flawlessly on the JD 6 cyl for near 20 years.

I was not surprised that the Chrysler module indicates 40 degrees dwell on the 8 cyl scale, that would be about right for a healthy spark on an 8 cyl engine running 5000+ rpm.
On a slow turning 6 cyl Like my JD that indicates about 55 degrees dwell and would be 80 degrees dwell on a 4 cyl engine.
Thats more than twice the time the coil is powered on the stock point ignition with 34 degrees of dwell time.
I can see where that could lead to the coil running overly hot in a slow turning 4 cyl application, although as I said, It has run without problems for 20 years on the 6 cyl JD.

Thats why I would like to hear from someone with a Pertronix module on a 4 cyl as to what the indicated dwell time is.

I have installed atleast 6 Pertronix ignition systems with the matched pertronix coil on 2-4 cyl tractors and skid loaders, and none have lost their happy, so am real interested why this one cooks coils.
 

A 4 cyl engine with mech points I would expect to have about 50 deg of dwell to 40 deg open points. That's 55% of the time heating the coil. I don't see how it's possible to have less than 45 deg. Are you sure this data is correct?

My neighbor has a dwell meter that we will use tomorrow to measure dwell on 3 4 cyl tractors with the pertronix EIM. I will post the data. I suspect higher dwell is responsible for hotter coils as other posters have suggested. Pertronix is very stingy with their data.

Thanks for posting your data.
 
I have been following this with interest. I run a Pertronix since 2006 on my 1966 140, born with a 12V genny but now running a Hitachi 14231, also since 2006. The coil is a NAPA 12V "External Resistor required" with a NAPA ICR13 resistor. The coil gets hot, but no hotter than it did with points. Same coil all seven years, plus some years when it was used with points.

I'll blow the dust off my dwell meter and see what I get tomorrow. I never USED the dwell to tune my 140 when I had points, but I would check the reading when I was done, just for fun. Seems to me high 30s was typical, but it's been 7 years.

I love the EI. With points, I could not get through the winter without changing rotor and cap. I never knew if it was going to start. The EI seems to burn through the condensation and starts strong all winter. (This is a snow-plowing tractor). I can't remember when I last had a cap/rotor fail. I'll never go back to points. If this Pertronix crumps, I'll buy another in a heartbeat.

But I am wondering if I should be happy I have the external resistor type coil.
 
If you are sure your tractor is wired correctly I agree that there must be a problem with your Pertronix system. I purchased a Farmall 300 a couple years ago with the pertronix ignition and it has not caused me one bit of trouble. A friend of mine had a pertronix ignition burn up on an 8N ford but he accidentally left the ignition switch on.
 
If the points on a mag are set to .013" the dwell will be less than 40. just geometry of bumps and cams. Jim
 
(quoted from post at 23:46:15 03/28/15) I have been following this with interest. I run a Pertronix since 2006 on my 1966 140, born with a 12V genny but now running a Hitachi 14231, also since 2006. The coil is a NAPA 12V "External Resistor required" with a NAPA ICR13 resistor. The coil gets hot, but no hotter than it did with points. Same coil all seven years, plus some years when it was used with points.

I'll blow the dust off my dwell meter and see what I get tomorrow. I never USED the dwell to tune my 140 when I had points, but I would check the reading when I was done, just for fun. Seems to me high 30s was typical, but it's been 7 years.

I love the EI. With points, I could not get through the winter without changing rotor and cap. I never knew if it was going to start. The EI seems to burn through the condensation and starts strong all winter. (This is a snow-plowing tractor). I can't remember when I last had a cap/rotor fail. I'll never go back to points. If this Pertronix crumps, I'll buy another in a heartbeat.

But I am wondering if I should be happy I have the external resistor type coil.

I got a dwell of 64, way up the scale. So there may be something to that theory. I'll watch the coil temp once I get to mowing season. I really hope snow season is over.
 

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