James, Thanks for the great post, Funnnnnnnnnn discussion, I love electrical chat, I will try n address your questions. At the end I will cover where you with the MSD info may be comparing apples to oranges i.e. just because Im right dont mean your wrong cuz use of an elec switch and a coil designed for such isnt the same thing as the old convention points ignition which the poster is using and upon which my answer stands correct based on the laws of physics..
QUESTION: I "not" douting you know what your talking about. If it made for a weaker spark then what would the point of it be?
ANSWER: The purpose of a ballast resistor is to reduce the amount of current flow in order that in a conventional points ignition the points dont burn up prematurely. In a points ignition where the coil itself already has 3 ohms of ignition circuit primary resistance the coil draws the 3 amps it was designed for but if you lower the current you lower the amount of stored energy the coil can achieve during its conduction cycle and less energy in = less energy stored and therefore less energy discharged across the spark plug gap. The coil is a passive energy storage device and the more energy in the more out soooooooo if you cut the current in half (approx what a ballast would do) theres less input energy n less output. If a coil is designed for 12 volts that allows x amount of current flow which a ballast resistor will reduce THEREFORE the laws of physics and conservation of energy dictates less energy in = less out i.e. use of a ballast (in this 6/12 situation) MUST equate to less energy in the coil = less energy stored = less energy discharged across the plug gap
QUESTION: If a ballest resister made for a weaker spark why the hell did they put them on every HEMI car or wedge car i have ever driven or seen.
ANSWER: Because in those systems use of a ballast accomplished a dual purpose. 1) If a ballast is external to the coil its possible to by pass it ONLY during cranking to get a hotter starting spark sice cranking drops battery voltage down. 2) If a ballast is used that again reduces the current throught the coil MAKING THE CURRENT THAT WHICH THE COIL AND THE SWITCHING DEVICE WAS DESIGNED FOR. In that case the current is correct WITH THE BALLAST IN PLACE BUT NOTTTTTTTT WITHOUT IT. That system was designed for x amount of coil current and for what current the elec switch could handle PLUS if needed (not all used it) an external balalst is able to be by passed for a hotter starting spark.....A BALLAST IS USED THERE CUZ THE SYSTEM WAS DESIGNED FOR THAT AMOUNT OF CURRENT AND IF THE BALLST WERE REMOVED THE COIL WOULD OVERHEAT PLUS THE SWITCHING DEVICE MAY BE DAMAGED. Howeverrrrrrrrrrr if you added yet another ballast, again same as my original answer, the spark will be of less energy
QUESTION: Automotive coils with out a ballest resister on tractors can cause problems ! It cost me a eletronic ign , it burned the eletronic pick up right out of the dist. Petronics told me to put a ballest resister in next time due to the auto coil.
ANSWER: Thats cuz the elec switch you used wasnt rated to switch the amount of current flow that coil was drawing buttttttttttt if the primary ignition was of more resistance (like if you added a ballast) then the current is reduced and the switch or coil dont overheat.....They have different current rated switches for different coil and/or coil and ballast combinations and in our case YES INDEED THE COIL NEEDED BALALST CUZ WITHOUT IT THERES TOO MUCH CURRENT WHICH CAN BE HIGHER THEN THE SWITCH WAS RATED FOR Fried switch grrrrrrrrrr Soooooooo if the elec switch vendor says you need a ballast then in that case yessssssss its needed so the switch dont fry due to too much current
QUESTION:There is no doubting you know the theory on how it all works, but not in this case.
ANSWER; Youre entitled to your opinion and I respect that butttttttt the laws of physics and conservation of energy in my opinion win out making me RIGHT in this case. Less energy into a coil (from less current) means less energy stored during conduction means less energy available to be dischaged across the plug gap
QUESTION: John i'm not taking a shot at you , i'm just passing on what i have learned and been told from the companys that sell the products.
ANSWER: Nor me at you, what you were told can still be correct buttttttttttt remember the use of an elec switch that was designed for x amount of current DICTATES the total primary resistasnce and if the coil isnt enough Then a ballast may be needed.
CLOSING: heres the deal, his question was for a points ignition system NOT an elec switch remember......The points can handle around 4 amps of current sooooooooo if his coil was 3 ohms THEN HE DONT NEED ANY EXTRA BALLAST BUTTTTTTTTTTTTTTTTTTTTTTTT IF HE WAS USING AN ELEC SWITCH that couldnt handle but say 2 or 3 amps YESSSSSSSSSSSSSS he needs a ballst or the switch will fry. What Im saying is you (MSD) can be right but Im also still right cuz we cant comparer an elec switch ignition to A POINTS system........They sell different current rated switches designed for diffetnt coil and/or coil + ballast soooooooo if they say a ballast is needed it is buttttttttttt if his points can switch 4 amps they can handle his coil UN BALLASTED. Yet if pertronix sells him an elec switch that cant handle 4 amps yessssssssss he needs a ballast
FINALLY Its IMPOSSIBLE to cover and explain all here in a few paragraphs that takes yearsssssssss of study to understand soooooooooo I just cant possibly cover and explain everything here to a non engineering or technical general group of people I JUST DO MY BEST TO HELP. If you study the physics of ketterign coil ignition systems n how coils work and understand the concept of conservation of energy you will understand why less energy pumped into a coil = less energy stored during its conduction cycle = less energy discharghed across the plug gap PERIOD and if you add an external ballast that means less energy i.e. weaker spark butttttttttttttt remember if the overall system is designed for a ballast then yes its needed otherwise the switching device overheats soooooo thats NOT the same situation as his example where points that can handle 4 amps is used and his coil resistane is such that 4 amps is available WITHOUT A BALLAST therefore if one were used the laws of physic dictates less spark energy. NOT the same as a situation where the coil and/or ballast was designed for x lesser amount of current which does require a ballast
AGAIN its IMPOSSIBLE to explain ALL THIS COMPLICATED STUFF to lay persosn but hey I do my best lol
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