Coil interchangeability?

[Mr. Recovery]

So relax, and take it easy..............at least until I finally realize my perennial New Year's Resolution of conquering the planet and enslaving the entire human population.



When that happens, you should be VERY AFRAID.


https://www.youtube.com/watch?v=bIZoVO8ZyyQ

dan-2beers.jpg

[Mark]

As linemen, long time ago, we'd test transformers for PCB, if it was above so many parts per million, we would replace it. Go back even further in time, we would take the top off of the transformer, put out hands/arms in the oil to change the tap changer or to parallel/series the windings.Eventually they learned the oil caused health problems.That could be the reason why the cancers showed up.

[Hell on Wheels]

Ok sorry if this is an old conversation and I usually spend my time on the G503, sorry dont hate. I have always forget to come here for the knowledge. Im interested in the youtube video send me the link. funny to see im a PFC here but a COl on the G503.

If someone can send me both a bad chinese and a bad NOS coil, I would be willing to perform surgery on them and document it like I did with the coil testing video on Youtube. Then we will all know once and for all what the differences are inside. A 10 thousand volts difference is huge and the chinese and black coil are not the answer.

[Hell on Wheels]

yes I just learned this lesson taking apart my distributor for maintenance and discovered the dioxins chem as Rick explained.



before:


after cleaning

Dioxins are a class of chemicals. The main ingredient in old dielctric oils, the thing that made them electrically resistant as well as thermally stable, was PCB, aka polychlorinated biphenyl. All dioxins are PCBs, but not all PCBs are dioxin. Dioxin is an unwanted by-product of PCB productions. Many, but not all coils can contain PCB oils, and that is only for coils made before 1979. And it was only for coils that did not use Shell dielectric oils, at the time marketed under the names of Diala, and Diala AX. None of Shell's dielectric oils have EVER contained PCBs. Shell produced an oil with all the necessary protections against electrical conductivity as well as thermal stability without using PCB oils. That was always one of their sales points.

If you have an old coil that has failed, use rubber gloves to clean it up. It is not like some sort of nerve agent like VX or Sarin. It is not instant death. There are still millions of electrical transformers, the type you see at every substation, and on every pole, still in use. But it is still something to not get directly on your skin. While it's toxicity is low, it's negative effects are cumulative.

Now for the supposed use of an internal resistor on the Chinese "chrome coils": I suspect it is true, and that it is an internally variable resistor, which would explain the lack of a difference in output with 12 vs. 24 volt input. With an internally variable resistor, the resistance increases as voltage increases.

This would explain a lot. Namely that the Chinese manufacturer knew that as voltage increased, so would heat, and that would shorten the life of a product they knew to not be made to the same quality standards as U.S. companies such as Prestolite.

[rickf]

[Christian]

Hi
I have been trying to find a wiring digram for the actual installation of the different types of coils and resistors. I have and old resistor with two wires, but I see on the photo that Ken posted, his had three wires (leads).
The resistor must hav a function in the circuit.
Hope someone can direct me to the circuit diagrams.

I have heard, that the reason for the resistor to be separate from the coil had two functions. One being the actual coil was made for 12 volt and therefore needed a resistor to work on 24 volt - by reducing the current through the actual copper coil and preventing it from overload. The other reason was for it to be outside the actual coil and therefor could emit more heat outside the coil housing when in operation.
Weather the above is correct or not, I am not sure, but it does sound plausable.

My experience with resistors in series with the primary coils on other vehicles (Toyota HiLux) is that these systems also have two ignintion leads. The system is, that ignition is by-pasing the resistor when starting, thus creating a greater spark when the engine is cranking (and voltage drops). When the engine is running, the ignintion current to the coil is passed through the resistor, the voltage now being higher. The coil was specially made for this operaton. The car actually worked ok with a "normal" coil (and original resistor) that was installed when the original gave up.

On the M151 we do not have two ignition leads, so it can not be the system described above.

I have found, that one reason some coils dont last long, is because the ventilating system for the distributor is blocked or faulty in some way. Fresh air should be let in from the fitting in the inlet to the carburettor and sucked out by vacuum in the manifold. If there is no airflow the coil may overheat.

Christian

[rickf]

Christian, the coils are all 24 volt. The older coils used the separate resistor under the coil but it only has two wires, one in and one out. As to the purpose of the resistor, I don't know. They are supposed to drop voltage on a normal setup but all f the older ones with the outside resistors I have tested showed 24 volts at the coil. Now, I did not check with them running so it may have limited the voltage at 24 volts down from the running 28 volts, don't know for sure. If there is paperwork out there on it then Ken will have it if anyone does.

[RAFINDER]

Christian, the coils are all 24 volt. The older coils used the separate resistor under the coil but it only has two wires, one in and one out. As to the purpose of the resistor, I don't know. They are supposed to drop voltage on a normal setup but all f the older ones with the outside resistors I have tested showed 24 volts at the coil. Now, I did not check with them running so it may have limited the voltage at 24 volts down from the running 28 volts, don't know for sure. If there is paperwork out there on it then Ken will have it if anyone does.

Hello Rickf, the function of the resistance in series with the coil is to protect the coil itself when we leave the ignition on without starting the motor. The resistor absorbs the voltage and prevents the coil from overheating and destroying it.

[RAFINDER]

Christian, the coils are all 24 volt. The older coils used the separate resistor under the coil but it only has two wires, one in and one out. As to the purpose of the resistor, I don't know. They are supposed to drop voltage on a normal setup but all f the older ones with the outside resistors I have tested showed 24 volts at the coil. Now, I did not check with them running so it may have limited the voltage at 24 volts down from the running 28 volts, don't know for sure. If there is paperwork out there on it then Ken will have it if anyone does.

Hello Rickf, the function of the resistance in series with the coil is to protect the coil itself when we leave the ignition on without starting the motor. The resistor absorbs the voltage and prevents the coil from overheating and destroying it.

It is advisable to install the resistance for safety of the coil.

[rickf]

Hmmm, Didn't work too well in that capacity since I have seen a LOT of cooked coils. I have two older ones here now that are cooked.

[Christian]

Hi.
thanks for the replies.
I have just had another look at the photo Ken posted. It could look as if one of the black leads is actually a shadow. This makes sense when reading the other replies.
@ rafinder - if the resistor is in series with the coil, I fail to see the how the resistor can "absorbe" more or less power depending on wether the engine is running or not with the ignition on. If the points are closed the current will flow and the resistance in the coil and resistor will be added together. if the points are open there will be no current and therefor no heat generated. could you elaborate ?

If the coils are all 24 volts design, (and the resistor is in series with the coil) then the resistor is to lower the voltage to this amount when the engine is running and generator gives off 28 volts at max. but it would also reduce the voltage during start when the voltage drops considerably when cranking the engine, thus giving a (theoreticaly) smaller spark.

Does anyone know the ohm value of the resistor?

We should all know, that you do not leave the ignition on if the engine is not running. But all of us tend to forget things when we are distracted. Then we buy new ignition coils

Christian

[rickf]

I measured one of them and I seem to remember 2-3 ohms? I will have to dig it out and check it again. Yea, we forget and have to buy a new one, which is about impossible to find unless you go the Chinese route.

[RAFINDER]

Hi.
thanks for the replies.
I have just had another look at the photo Ken posted. It could look as if one of the black leads is actually a shadow. This makes sense when reading the other replies.
@ rafinder - if the resistor is in series with the coil, I fail to see the how the resistor can "absorbe" more or less power depending on wether the engine is running or not with the ignition on. If the points are closed the current will flow and the resistance in the coil and resistor will be added together. if the points are open there will be no current and therefor no heat generated. could you elaborate ?

If the coils are all 24 volts design, (and the resistor is in series with the coil) then the resistor is to lower the voltage to this amount when the engine is running and generator gives off 28 volts at max. but it would also reduce the voltage during start when the voltage drops considerably when cranking the engine, thus giving a (theoreticaly) smaller spark.

Does anyone know the ohm value of the resistor?

We should all know, that you do not leave the ignition on if the engine is not running. But all of us tend to forget things when we are distracted. Then we buy new ignition coils

Christian

Hello, indeed if the points are closed, the current will flow and the resistance in the coil and the resistance will add up, but it is absorbed by the resistance because the coil is inductive.
And if the points are open there will be no current and therefore no heat will be generated.
It also protects the electronic ignition if you have it installed.

[RAFINDER]

I measured one of them and I seem to remember 2-3 ohms? I will have to dig it out and check it again. Yea, we forget and have to buy a new one, which is about impossible to find unless you go the Chinese route.

Indeed Rick, the resistance value is between 1.5 and 3 Ohm.

[Christian]

HI.
This is an enjoyable discussion even if it does go a bit "nerdish" at times. We all learn all the time.

@ Rafinder - it is true that the coil will react as inductive resistance, but will this not only apply when the current direction is changed ? If there is a change in current direction the formular for resistance should be XL = 2 x pie (3.14) x f x l => Ohm = 2 X pie x Hz x Henry.
With direct current DC and the points closed, there will be no change in the current direction. so it should only be the copper resistance that results. This in turn will create the heat in the coil. The effect being P = U2/R => Watt = volt2/Ohm

I feel we are getting closer to what the external resistors purpose is.
Christian