John T said: (quoted from post at 10:10:24 11/03/09) Sorry I arrived late, but as an electrical engineer I love this sparky chat......A couple engineering points.....
1) I AGREE WITH JIM (janicholson) the location of the ballst resistor DOES MAKE A DIFFERENCE which is why factory set ups ALWYAS had the ballast BEFORE the coil NEVER between it and the points YUKKKKK. Sure its a series LR circuit when the points are closed and at steady state during that time the condensor is shorted out by the closed points (LR ONLY),,,,,,,butttttttt when the points open then its a series LRC circuit and theres ringing and oscillation occuring between the condensor and coil (thats just an LC circuit mostly) until its all damped out i.e. the condensor charges up and stores energy but then it gets discharged (back into the coil), (Ive seen oscilloscope prints of that action). In the factory wiring the coil and condensor are next to each other in series with NO RESISTANCE BETWEEN THEM (its BEFORE the coil remember) any resistance between them (when the ringing oscillation occurs) would serve to discharge energy in the form of wasted heat versus it getting fed back direct to the coil where that energy gets transformed into magnetic energy storage and transfer over to the secondary and out to the plugs where it does more good then the ballast wasting it as heat.
2) THE COIL POALRITY WIRING INDEED ALSO MAKES A DIFFERENCE Why you think the factory bothers to label those lil terminals + and - ??????????. Its easier to discharge electrons from a hotter surface (plug electrode) to a relatively cooler (plugs ground strap) surface. Thats why in vacuum tubes theres a heater located under the cathode to HEAT IT UP to easier emit electrons up to the cooler non heated plate. A retired physicist friend of mine actually took measurements of firing voltages when coil leads were correct but then reversed and found it was several thousand volts less if the coil was wired correct. i.e. if at reverse polarity the coil has to work harder and heats up more and is less efficent becasue it takes more voltage to arc jump the gap if the electrons have to flow from a cold to a hotter surface. SURE she still sparks either way butttttttttt its more efficient and the coil wastes less energy in heat if its wired at the correct polarity.
DISCLAIMER hey its IMPOSSIBLE to explain the Kettering coil ignition system in a few sentences here as that takes entire books and years of study to accomplish, so the above is wayyyyyyyyyyyyyy over simplified and perhaps not 100% perfect but its how I best recall it works and WHY THE BALLAST GOES BEFORE THE COIL AND THE COIL POLARITY MAKES A DIFFERENCE. I graduated from Purdue EE in 1969/1970 so Ive slept some since then lol but this is my ebst effort to help yall (especially non electrical engineers and technicians) understand
God Bless yall for your help here
Ol John T BSEE,JD in Indiana
PS My Ignition Troubleshooting may also help the original poster
Well, John, I like a lot of your posts, but this last one isn't totally on the mark. ALWAYS (as in ballast always goes before the coil) is a big word.......see Attachments. Clearly these Delco engineers didn't know about 'always' (Delco, home of Alfred Kettering).
You say condenser discharges back into the coil with no resistance between them. For the condenser to coil transfer to take place, current must flow from condenser to coil and current must have a loop in which to flow AND no matter where that resistor is physically located, that current flows thru it and the battery and the connections of condenser to ground thru ground thru connections to battery. So, no it does not matter electrically where the resistance is located. I don't need to see "oscilloscope prints), I can see the real thing in my shop now or any time on this set up as it exist at this very moment.......come on over any experiment all you like. Welcome anytime.
I didn't say polarity didn't make ANY difference, just not significant difference. Yes, I am fully aware of thermionic emission, just like your self. It's nice, but clearly not very important for several reasons, 1) it isn't there when you need it most at cold starts, 2)magnetos work just fine where every other spark is of opposite polarity, 3)all old Harley's used one coil where each plug received output from opposite ends of coil, so half the sparks were of one polarity & half the other polarity, 4) many current day electronic ignition engines use fewer coils than cylinders (3 coils for 6 cylinders for example) and result is half run on negative polarity spark and half run on positive polarity spark (how is you Ford V6 running?).
Yes, I'm an 'outsider' and Jim, Gene, John are all insiders, but I'm not wet behind the ears and support my position with facts, but still will be beat about the head & shoulders anyway.
In so many of these things I'm bothered by the acceptance of various things 'because that's the way they have always been', rather that by a factually supported answer to the question, "why?". A daughter ask her mother, 'why do you always cut the end of the ham bone off & drop in in the pan beside the ham?".. Mother responds, 'because my mother always did it that way'. So, the daughter goes to he grandmother an ask her 'why she cut the end off & dropped in in beside the ham?'. Grandmother said, "because I never had a pan big enough to fit the whole ham". Took couple generations, but it was learned, 'why'.
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