Will ANY 12V internal ballast ignition coil work?

I have a Ford 4000 that's been converted to 12 volts. The coil tests iffy on it, so I'm replacing it.

The coil on it now is an externally ballasted one. It has a ballast resistor strapped to the side of it and the + side of the coil running through the resistor and to the side of the distributor.

The Ignition post from the starter solenoid to the - terminal on the coil shows 0 ohms resistance.

I take this to mean I should just use an internal ballast coil.

So, since I have several coils on my shelf already, can I grab any one of them that is internal ballast 12v, and it's good to go?

You want the resistor in the wire between the switch and the coil, otherwise the coil gets hot.

Yeah I saw that and wasn't very impressed with whoever did the wiring job on it.

i should be able to toss the coil and the resistor and put in a coil that doesn't need a resistor, but will any of them work?

any direct 12 volt no resistor required coil should work. It you have one, try it.

What are the symptoms and what tests did you do to believe the coil is bad?

I take it you have a 4 cylinder 4000. Love those tractors.
Any 12V coil marked no external resistor required or similar
should work. NAPA IC14SB or equivalent.

symptoms are here: http://forums.yesterdaystractors.com/viewtopic.php?t=1138588

I'm partly just grasping at straws trying to find anything that might be causing the problem, but I ran a multimeter from the + to the - terminal on the coil, and it gave me an infinity reading. My understanding is it should read between 1.5 and 3 ohms.

(quoted from post at 18:43:39 06/11/14) I take it you have a 4 cylinder 4000. Love those tractors.
Any 12V coil marked no external resistor required or similar
should work. NAPA IC14SB or equivalent.

Click to expand...

Yep. a 1963 4 cylinder. I'm very excited about this tractor, I really like it already. It's a big step up in power from the Massey TO35. I just need the darned thing to run properly.

I checked all the coils I have and apparently they're all for electronic ignition and don't have threaded studs on them. I'll run down to NAPA tomorrow.

Doing something wrong there. If I understand you, it runs but you measure infinity across primary. Ain't gonna happen!

Not to thread hijack but the question seems relevant -- I have a 6V coil with a resistor on my tractor that I'd like to ohm out to see if it is any good (it's been converted to 12V). What's the best way to ohm it out to see if something is amiss with it? Across the coil itself? From the coil to the chassis? To the battery?

(quoted from post at 21:54:21 06/11/14)

(quoted from post at 18:43:39 06/11/14) I take it you have a 4 cylinder 4000. Love those tractors.
Any 12V coil marked no external resistor required or similar
should work. NAPA IC14SB or equivalent.

Click to expand...

Yep. a 1963 4 cylinder. I'm very excited about this tractor, I really like it already. It's a big step up in power from the Massey TO35. I just need the darned thing to run properly.

I checked all the coils I have and apparently they're all for electronic ignition and don't have threaded studs on them. I'll run down to NAPA tomorrow.

Click to expand...

Double check your meter and spark first.
In your other post you said it had good spark.
If it still has [b:4a16689b1d]good[/b:4a16689b1d] spark the problem isn't the coil.

Based on what I have experienced, the answer to your question is both yes and No.

Yes, you can put any 12v internal resistor coil on and it will run. (for a while at least)

But:

The original idea was to match the capacitance of the condenser to a coil with a particular internal resistance This was done so that there would be as little arcing/sparking at the points when they opened as possible.

So: If you just put any 12v internal resistor coil on, you probably will have shorter than normal point life. Ideally, you need to install the correct condenser for that particular coil to get the maximim life out of the points.

(I know that now with China making all the replacement parts, how reliable that idea is today.)

My personal experience is the same: You can install any coil, but don"t expect the points to run long without attention/cleaning,etc.

Despite many old wives tales and incorrect beliefs out there and Billy Bob and Bubbas thinking there's a ballast resistor tucked away and hidden somewhere inside a typical 12 volt circa 40's through 60's tractor coil ,,,,,,Typical coils labeled "12 Volt" or "12 Volt not for use with ballast resistor" or "12 Volt no Ballast Required"

HAVE NO DISCRETE STAND ALONE INTERNAL BALLAST RESISTOR INSIDE THEM (even though Billy Bob and Bubba call them internally ballasted coils)

That being said, on a 12 volt tractor you can use a true 12 volt coil (with NO external ballast required) and such are usually labeled as above.

If you want to use a 6 volt coil on a 12 volt tractor, then you do need the external series voltage dropping (12 to 6) ballast resistor so the coil only sees 6 volts and doesn't overheat.

Many old 12 volt tractor coils (Im NOT talkin high voltage or high energy or high performance or Accell or Mallory automotive racing coils) have a LV primary resistance in the 2.5 to 4 ohm range with 3 ohms often found.

Got it??

John T Retired Electrical Engineer

Many old 12 volt tractor coils (Im NOT talkin high voltage or high energy or high performance or Accell or Mallory automotive racing coils) have a LV primary resistance in the 2.5 to 4 ohm range with 3 ohms often found.

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Very good information. Just curious -- do old 6 volt tractor coils ohm out similarly, or a little higher/lower?

I assume a coil can fail shorted (nearly 0 ohms) or open (towards infinity ohms, but probably will read in the Mega Ohms range).

And can you measure the coil with it wired up, or do you need to remove the wires to it to do so? I know sometimes when ohm-ing things out you get weird readings if you have other items in circuit (like capacitors that are charging -- ie. the condensor?).

I actually was aware that there's not really a little ballast resistor tucked away inside the coil, it's just simpler to say "internal ballast coil" as most people generally know what you're referring to.

I have this feeling that my test was not run correctly, since I DO have a good strong spark when grounding the plug with it pulled out, but considering how strangely it was wired in I thought I would give it a try with using a new coil.

Thanks for all the information. You learn new things every day.

Oh, and the test was made with all wires taken off of the coil.

(quoted from post at 23:27:30 06/11/14) I actually was aware that there's not really a little ballast resistor tucked away inside the coil, it's just simpler to say "internal ballast coil" as most people generally know what you're referring to.

I have this feeling that my test was not run correctly, since I DO have a good strong spark when grounding the plug with it pulled out, but considering how strangely it was wired in I thought I would give it a try with using a new coil.

Thanks for all the information. You learn new things every day.

Click to expand...

I'd hate to see you spend money on a new coil you didn't need!

If I had to guess I'd say the reason my test failed is just from corroded terminals on the coil.

At this point though I'm all out of possible reasons why the tractor isn't running right, and a new coil is the cheapest of the possible things I can start replacing.

I'm looking at either a new carb, or perhaps the mechanical advance in the distributor isn't working right. However the timing mark on the flywheel doesn't seem to jump around on me, so I don't think that's it.

I suppose I should do a compression test on the engine too.

If you're getting a good spark, and nothing is
heating up, the points are burning normal, I would
assume the ignition system is not the source of
the problem. The only other thing to check is wear
in the distributor shaft bushings, they can do
some strange things.

I looked at the old post, said you had just got
this tractor, and the carb looked like it had been
rebuilt. Also sounds like it will start without
choke even cold? That's not normal for an
updraft. Possibly someone has been tinkering with
the carb, and over did something that couldn't be
undone, as in drilled out an idle jet, plugged an
air vent, who knows...

Any way you can do a carb swap just to see what
happens? I fought a carb problem on a Ford
tractor, think it was a Holley, could NOT make it
run right. Finally bought a new one from the
dealer, different brand, solved all the problems.

Never hurts to do a compression test, though I
doubt that's it.
I don't like to buy parts. They're pricey!
The carb can be fixed if that's the culprit.
Unless it's warped or something weird like that.
Have you cleaned all the fuel screens and the
sediment bowl?
Do you have good fuel flow out of the plug in the
bottom of the carb bowl? Say a pint per minute?
It should be steady. Catch it in a glass jar,
check it for water/dirt and put it back in if
clean.

I know you just bought it, but do you have any
history on this tractor? Has the engine been apart
lately?

I believe I'm getting good spark, but that's just while cranking it over with a plug out. I'm not sure how good or stable the spark is while running. I don't really think the coil is the culprit though, but I figured it was an easy $18 process of elimination, since it obviously wasn't wired in right anyway.

The engine does warm up very quickly by the way, much quicker than I would think it should. And no, no choke ever. It won't start I use the choke, even when cold.

My two best guesses at this point are exactly as you said Steve, I'm wondering if someone screwed with the carb and drilled something out on it. My other guess was the distributor having an issue somehow. I didn't think about the bushings on it.

Royse, I've cleaned all the filters and screens. The sediment bowl and screen look brand new. I believe they were replaced when the carb was rebuilt.

I have very good flow. Someone put an inline fuel filter in front of the sediment bowl. So I pulled each part of in turn, and checked flow. I checked the fuel filter, blew through it, no restriction at all. I checked flow with the bowl off and it's flowing at about the same rate as directly from the fuel line, and the drain on the carb is the same. I haven't measured it, but it puts out about a steady 1/4" stream. I'll try draining it in a pint jar and checking it. The inside of the gas tank looks new.

The history of the tractor is that it was in a barn in a farm somewhere, a guy bought it just because he liked it about 5 years ago, paid to have a bunch of work done to it, including wiring etc. Then it sat, no one used it, he died, and his sons sold it. I believe before they sold it the sons paid to have it gotten running again, probably why the carb rebuild looks so fresh. The wiring conversion on it appears quite a bit older, the carb looks fresh, in the past few months or less. Everything is bright and shiny on the carb.

OK, just trying to understand the question here.

Is the tractor in question running poorly? You failed to mention that. If it's running good, starts well both cold and hot then what's the problem? Run her till she dies!

Rick

Running very badly. To even get it running at all I have to have the timing so far advanced (around 30 degrees or more BTDC) that it diesels when turned off and pings badly when under any load. I also can't rev it up without it dying unless it's very slowly and carefully.

Please don't send your ugly neighbor over to my house for suggesting somthing trivial. The huge timing advance coupled with the comment about timing mark being rock steady stricks me as unusual.
Have you checked to see if the plug wires have all been moved around one hole in cap?

I have a 1963 Ford Industrial 4000 with the 172
engine. It has a heat-sensitive external ignition
resistor. When cold it has little resistance.
When hot it gets high resistance. Works like a
voltage regulator. Sends near full batery
voltage when cranking and when the engine is hot
and less ignition power is needed - it increases
resistance. This sort of heat-sensitive resistor
is common on American made four-cylinder Fords.
If turn the key on and do start the engine - in a
few minutes smoke will come off that resistor
because it gets so hot (without the engine
running). That is normal.
Seems everytime someone asks a question around
here about coils -the answers go wild and then
much is declard bogus because "Billy Bob or Bubbs"
chimed in.
Well - #1 I own a 63 4000 Industrial. Had it
for near 30 years. It needs a minimum of 9 volts
at the coil primary to work correctly (where the
IGN wire hooks to it). If you have at least 9
volts and it does not run right -you've got
problems unrelated to any resistor in the wiring.

Note that any 12 volt system is designed to work
well at 9 volts and not just a Ford. A 12 volt
system is designed to make good spark from 9 volts
to 14 volts.

A coil that does not need an extra resistor in the
outside wiring already has extra windings of wire
inside to make that extra resistance. Easy to
measure with an ohm-meter.

You can go to NAPA and buy a coil with the built-
in extra resistance and it will say on it (not for
use with external resistor). That will work fine.
Or you can buy a coil that requires and outside
resistor and it can be used on a 6 volt or 12 volt
tractor.

If I understand what you are saying, the resistor as now wired is reducing the grounding of the coil by the points for each coil firing. The resistor needs to be between switch and coil.

If you have an IGN post on your starter solenoid -
sounds like it is being used as a resistor bypass
when the engine is cranking. Nothing wrong with
that. But when not cranking - power to the coil
primary comes from the ignition switch. An
external resistor will be in that circuit
somewhere.

If you have used coils in your shop -you can
determine if they need external resistors by
checking resistance across the primaries. If 1 to
1.5 ohms - it needs a resistor if used with a 12
volt system. If high - around 2-4 ohms - NO
external resistor is used.

Thanks all for all the advice. I'm working on it, I'll let you know if I get anywhere. As suspected, it wasn't the coil.

Da.bees, I do have an ugly neighbor, but he's not very big. No worries there. And it usually is something trivial that I've overlooked, so I'm glad to hear it. But no, I did check that all the wires were correct and the firing order was correct. TDC on the number one cylinder corresponds to 0 on the flywheel, and the rotor pointed at the number one plug wire. I even checked the rotation to make sure they weren't plugged in a reverse order.

I have an 800 with the same engine. On the heating up real quick- there are at least 2 head gaskets for that engine and one of them is missing some coolant passage holes the other has. Twice I've been given the wrong head gasket. If "a bunch of work" was done on it some time back and the head gasket was among the work, I'd be checking that.

Have you checked valve clearance? Restricted muffler/exhaust? Correct plugs? I'd do a compression check too.