Magneto or Distributor?

dmat58

Member
I have a Farmall 100 and I have a distibutor and a magneto for it. Which one would you use and why? Thanks
 
Personally, I like mags. When they are right, they produce great spark........even if your battery is DOA. They are a little harder to maintain than a battery ignition, but not that much more. Batteries fail. They can run down. They have to be charged. In cold weather, my opinion is that a mag ignition works much better. The mere fact that regardless of battery condition, a mag tractor will start and run is the selling point for me.

At the end of the day, both ignition types are fine, but I prefer the mags.
 
Do you have the rest of the electrical system and is it in working order. I'd consider the cost of all that stuff in making a decision.
 
I would go with the mag just to be different. Werent the mags still avaliable from fact cause i read mags were still an option till middle 50s.
 
Do you plan on hand cranking it or use the electric starter? A battery ignition unit will give you a smoother running engine at lower engine speeds. Having worked on magnetos on IH tractors for many years I much prefer the battery ignition unit. It is much more adaptable to different engine options such as fire crater pistons, step head pistons etc.
Also, if you remove the DISTRIBUTOR from the magneto your engine will not run. Had to throw that in.
 
Pete, I agree with you that a battery ignition is much more adaptable if you are going to modify an engine, such as to make it a puller, up the compression, etc. etc. etc.

However, for a stock engine, not sure why you say it gives a smoother running engine at lower RPM's? I agree, that the faster you turn a mag, the "hotter" the spark, but at stock RPM's the H4 mag produces a fat spark. I have a BN and an A both with stock C113's that idle VERY nicely.

Also, when the weather is cold, a mag will produce a much hotter spark than a battery ignition due to the voltage drain of cranking a cold engine. that of course produces a more consistent cold starting engine.

so, I am not challenging you, but actually would like to understand your low RPM statement.
 
BOTH are good, each has advantages and disadvantages. Before tractors had batteries they sure came in handy lol. But with batteries and charging systems they gave way to battery powered coil distributor ignition systems. Still great in aviation uses.


Mag advantages are NO BATTERY REQUIRED.
disadvantages are usually no RPM based
variable spark advance like a distributor,
simply two timings, start and run timing.
more parts and maintenance due to impulse
assembly.

Distributor advantage variable RPM based spark
advance timing.
ability to produce (via stored
battery energy) and discharge more
spark energy then a mag especially at
low RPM.
disadvantage IF NO BATTTERY NO SPARK

There are others, its a persons own preferences.

John T
 
The centrifugal advance built into the distributor drive shaft (under the plate that the points mount on) allows timing to be closer to TDC at idle, and farther from TDC at full rated RPM. This is important for smooth idle and good combustion through all operating speeds. Fuel in the combustion chamber burns with a predictable flame front (leak a trail of gasoline for 50 feet and then put a match to one end. The time it takes to ignite the fuel at the other end is the flame travel rate in air, no compression. The same happens in the combustion chamber, only we can't see it. The change in timing accounts for this variation, which in turn allows maximum cylinder combustion pressure to occur ~ 8 to 10 degrees after TDC. Smooth. Jim
 
Jim and John, 100% agree with your comments. There is an interesting article in the SAE archives around this. WILLIAMS, J., "MAGNETO VS. BATTERY IGNITION," SAE Technical Paper 170050, 1917, doi:10.4271/170050

Seems that a combination of things went into the early decisions around Mag vs. battery ignition. One of them was the different operating environments for a automobile vs. tractor vs. industrial power unit.

A battery ignition as stated, produces a more consistent spark over a wider range of RPM's. No question there. However, a tractor or power unit is designed to be taken up to operating PRM's and run that way for long periods of time vs. an auto that is constantly changing speed accelerating or decelerating.

With that all said, a battery ignition will provide better spark characteristics at lower rpm's when considering high compression and different octane fuel. In the end, I 100% agree with the both of you (and Pete) about how the battery ignition behaves. I guess my point is, on a stock C123 engine (in the case of the Farmall 100) under normal use RPM's and standard Regular grade gasoline, I think the mag would perform the same as the battery ignition without noticeable difference in low RPM operations.

If you are going to jack up the compression, change the cam timing and lift, etc. then the battery is the only way to go. For normal operation, my point is there is negligible difference, if any. Plus, the inductance of the coil is related to voltage. Go take a voltage reading on your battery at -10 degrees while cranking. Take that same reading at 60 degrees while cranking. Since the coil's inductance is directly related to the input voltage, I like mags for starting in cold weather.

but John, you said it best. Both are good. Both have advantages and disadvantages, which I think I also said, just in more brevity in my initial post. I could have done a better job of stating that for [b:2f573347e7]this application[/b:2f573347e7], I don't think there is a significant difference in performance between the two.

Good posts, good thread. :D
 
If a mag ignited tractor (such as a letter series Farmall) with no "spark" lever is setup to have close to perfect full power timing, it will idle with a noticeable unhappy sound, and moderate lumpiness. If the timing is changed while it is running back to a few degrees before TDC, it will smooth out and pick up RPM. Many a Farmall is operated cultivating, live planting, or doing light work idled down in a higher gear. The fuel efficiency and reduced engine heat are worth it. If they made timing controlled mags (or lever adjustable mags like the old old days) they would be equal. Jim
 
The reason I say battery ignition makes for a smoother running engine at other than full throttle is because with a magneto, as used on these models, the spark advance is full at all running speeds. Only retarded with a impulse for starting. Listen to all those little pops in the exhaust at low rpm on magneto equipped engines. Hear that flap on the muffler slapping back and forth. That is due to improper advance for that speed. I am not talking about pulling tractors as I have no interest in them. I am talking about customers tractors brought into shop for repairs in the years I worked at dealer. Talked more than a few into getting rid of the magneto over the years. Very few if any old tractors are running with their original bore, compression ratio's etc. So , they are all modified to some extent.
 
If you have a good electrical system through and through, I would lean toward the distributer. If your electrical system has some weak points that you might not be going to do anything about, or you plan on or like to hand crank start it, I would go with the mag.
 
I have found that in extremely cold weather , it will start better with a dist & hand crank. The mags get stiff & the impulse doesn't snap like it should.
 
Yup, rotor and cap, that is the distributor. It distributes the spark to the multi cylinders. That is why it is incorrect to call a battery powered ignition unit a distributor. A H-4 magneto uses a distributor just the same as a battery powered ignition unit does. Some magneto's do not have a distributor like on a single cylinder engine or even some two cylinder engines but the battery powered units used in the same application also do not use a distributor.
 
Guys, I have to say it again. This is a great post/thread. what we have done here is provide solid information around pro's and con's for each.

People can now make decisions based upon facts. Pete, John, Jim, excellent input from guys who know!

and others too!
 
Being a sparky like Jim and Bob and others I ENJOY THIS CHAT even if others are bored stiff lol

PS if you want to realy really get bored by sparky chat and see feuds going on, stroll over to Tool Talk WOWWWWWWWWWWWWWWWW

John T
 
The only problem I see with your mag is it may be 60 years old if its the original mag and the magnets may be weak. Hal
 
Hal, while that is possible, the Alnico magnets used in the H4 and J4 series mags really holds it's magnetism, and while not impossible, it is rare that I see an H4/J4 where the magnet is weak enough to require recharging. On the iron horseshoe mags, absolutely. Over time, they will weaken. Interesting thing about those is, however, that they get better with age, meaning their ability to hold their "charge" gets better with time. So, when you do recharge one, they hold it longer as they get older. It is interesting how that works. to John's point, if anyone would like to understand the different types of iron crystalline structure, and how those different forms, and crystal orientation effect the magnetic properties, ask. Will be happy to share! That is why you can heat a piece of iron or iron based alloy to a certain temperature, and it will lose it's magnetic properties.........until it cools down again. All good stuff.

John, I know EXACTLY what you mean. People get their knickers in a knot pretty quickly. That is part of the problem with these online boards. People can't hear the inflection in your voice.......they can't see the expression on your face. so, people can take things the wrong way really quickly. I have been doing mechanical work for over 40years (first for a living, and for the last 30 years on the side), and I still learn something new in discussions like these each time they happen.
 
So, can you explain what is in a magnetic field, where it comes from & why like poles repel & unlike poles attract?
 
Ok, here is the high level fly-by, and we can drill deeper if anyone wishes.

Iron and iron base alloys (steel) have multiple crystalline structures bases upon temperature, heat treat, alloy, and some other lessor facts. The crystalline structure of iron compounds that is magnetic is called Ferrite. When you heat Ferrite to the Curie point (temperature), the crystalline structure changes from Ferrite to Austenite. This also changes the shape and electron structures within the crystals. Austenite is NOT magnetic. hence, when you heat a magnet to the Curie temperature, it loses it magnetism.

So, why does it lose it's magnetism? Again, has to do with the electrons in the Fe (Iron) atoms, the crystalline structure, and the orientation of the spin of the atoms. When the orientation of the electron spin in the crystalline structure is aligned (through the magnetic field, ie. magnetic charging), the iron or iron alloy retains and produces a magnetic field (measured in magnetic moment, which is Newton-meters (Joules)/Teslas, basically a vector. It can also be measures as Gauss) Basically magnetism is measured by the amount of torque per Tesla

North and South poles on a magnet, can be explained in very simple terms that the electron spin alignment is 180 degrees opposite or "out of phase" for the magnetic dipole (poles).

so, to fully simplify, the electron spin orientation within the Fe crystals produces the magnetic field. Changing that crystalline structure through heat or magnetic induction, will modify the magnetic field produced. The various crystalline forms of iron are called Allotropes.

If you would like the math and more information such as specific crystalline geometry, we can continue. Remember, iron and iron alloys all have a crystalline structure. Heat treating and alloy components effect the crystalline structure and subsequently the magnetic and physical characteristics of metal.

Hope this provides a basic answer to your question. 8)
 
Explaining what is in a thing with no mass or matter is not possible. It is one of the four forces at a distance Gravity, Electromotive, Weak Atomic force, and strong atomic force. Graviton, Photon, W and Z bosons, and Glueon, being the carriers of these forces. Jim
 
One thing I forgot to clarify (I assumed, which is bad, bad, bad), is that at the atomic level, temperature is actually vibrations in the atoms, and is directly proportional to (measured by) KE (kinetic energy). Now, when matter goes from a solid, to a liquid, to a gas, what is happening is that the KE of the atoms exceeds the inter-atomic electromagnetic attraction that exists. Also, the entropy (disorganization) of the atomic structure increases as the temperature increases. It is the structured alignment of the atoms, and the orientation of the electron spin in a crystal that produces magnetism. When you heat it up, the entropy increases, so the orientation of the electrons gets all "jumbled" up, so to speak.

Same thing happens when you de-magnetize something. you are "un-aligning" the orientation of the atomic structure and electron spin in the material.

If you want to "supercharge" a Fe based magnet, you can do it with super cooling the magnet as well. All based upon electron spin and crystalline composition of the material.

Everyone snoozing yet? LOL
 
That is where you are wrong, Jim. What is in a magnetic field is matter in motion. It is the smallest entity of matter. It travels and spins at C. E = m x c x c. Anything spinning will take on the characteristics of a gyroscope. Magnetic lines of force are curved so the particles travel in a helix or corkscrew. The spin of unlike poles cause the particles to turn into each other just like corkscrews (attract) & like poles are turning opposite so they turn away from each other. (repel) Clear as mud?
 
You are getting close. Now explain how the permanent magnets in a heater motor or in a starter can keep producing energy start after start when it only takes a few watts to charge the magnet?
 
Here's a Wico mag with dead magnets. It's off a Standardtwin garden tractor. I could've had them recharged, but I found another mag. A lot of these
old garden and farm tractors were never sheltered.
That makes a big difference here in MD from rain, snow and fog. We had machine sheds on the farm
and my dad would say if you have enough time to take out the tractors or implements take time to shelter them. The only thing I leave out is my old wheel barrow. I've replaced the wooden handles several times. I have one with dual wheels, but its buried in the garage. Hal
PS: The military used mags on their gas engines. The M48 tank had 4 mags all timed to the flywheel.
The engine was V12 with 1790 CID. It also had 24 sparkplugs 2 on each cylinder barrel.
a174316.jpg
 
if you go to a parts place and ask for a dist for a H-4 Mag you will get raised eyebrows. Thats why the rotor and cap for a mag is listed as such and sure not a dist.
 
You ask for the distributor cap for an H-4 mag or you may end up with the cap that covers the coil. I have even seen that discussed on here a while back where some one asked what cap some one was telling him to get new for his magneto.
 
They do not produce energy. They just provide a magnetic field upon which the magnetism (from the armature) reacts. They do not have energy stored in them, they have directional magnetism resulting from alignment of atom's spins. QED Quantum Electrodynamics. I cannot respond to the discussion further, not because I have no podium (acceptance of QED is pretty much universal) it is because there is no way to prove either of our conjectures in simple dialog. No Offense intended. Jim
 
Once you understand something, it becomes very simple and very obvious. Magnets produce their own energy by E=M x c x c. You are trying to make it difficult when it is very simple to me. No offence either. It only takes a few watts to align the atoms. Then the field is coming from the atoms. (M) A permanent magnet starter will keep starting for years & produces way more energy than what it took to align the atoms. Lets put 746 watts in a conventional starter. It should produce about 1 HP. Then put 746 watts in a permanent magnet starter armature & it will produce more than 1 HP. It all boils down to E=MXCXC.
 
(quoted from post at 23:00:06 11/16/14) Once you understand something, it becomes very simple and very obvious. Magnets produce their own energy by E=M x c x c. You are trying to make it difficult when it is very simple to me. No offence either. It only takes a few watts to align the atoms. Then the field is coming from the atoms. (M) A permanent magnet starter will keep starting for years & produces way more energy than what it took to align the atoms. Lets put 746 watts in a conventional starter. It should produce about 1 HP. Then put 746 watts in a permanent magnet starter armature & it will produce more than 1 HP. It all boils down to E=MXCXC.

WOW!
 
Air planes did indeed use a magneto and some if not all used two of them just in case one failed.
 
Well, I am going to follow Jim's lead and bow out here. I will leave though with some commentary about the conservation of matter and energy.

Teddy52food, not sure if I misunderstand your wording, or if you are mis-representing your statement. However, magnets do not produce energy in the classic sense. you cannot get more work out of a motor than the energy you put into it. That, I will debate with anyone. However, if your articulation was meant to imply that a permanent magnet motor is more efficient or has more torque than other types, then yes, I agree. The physics around the conservation of Mass and Energy apply. So, yes, the magnetism remains. It allows for an efficient motor. however, you are ADDING energy to the motor through the electric current......starters don't work on their own. The magnetism in a perm magnet starting motor allows it to work, only after you energize the windings, but it does NOT add net energy to the motor to perform work. remember, Newtonian mechanics: Work is measured in Joules. The unit for Joules is Newton Meters. Newtons: 1 N = 1 kg⋅m/s2 or for electricity, 1 Joule = 1 watt per second. ok, this is now going down a whole other path..........

I still say this was a good thread, albeit it took a left turn in Albuquerque............ as Bugs Bunny said. all good. no offense meant or taken to anyone.
 
They are getting more torque on a PM starter with less input. This is because the PM fields ARE producing energy by E=M x c x c. Years ago the heater motors with field windings were fused at 30 amps. Now with the PM fields the amps are about half. Are they blowing less air? No, I don't think so. Open your mind. This is real. This should be brought up to our youth with young uncluttered minds, as most of us are old & set in their ways. It is a new source of energy.
 

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