Posted by JMOR on November 24, 2021 at 01:28:10 from (76.187.207.141):
In Reply to: spark coil questions posted by Bob N.Y. on November 23, 2021 at 14:06:20:
Summarizing, my view is that if factory proper positive ground system is change to negative ground battery & nothing else is done, the negative HV spark will simply become a positive HV spark. Same magnitude, reversed polarity HV out.
Then, if coil wires are reversed, the HV will now be negative, magnitude will decrease by the amount of primary voltage during spark (called 200v), IF this wire reversal results in changing the pri/sec common tie point inside the coil from 'connected at battery' to connected tie point being 'connected at distributor. Therefore, whether reversing coil wires results in HV increase or HV decrease, depends on where windings common tie point is located. The front mount square can coil has tie point at stud (battery), so such a wire swap on it will result in the HV decrease. If apply DC battery voltage to pig tail and stud (use resistor to reduce current) and connect a voltmeter to HV output and touch one at a time, the other meter lead to stud, then pig tail. Which ever shows ZERO voltage is common tie point. And finally, then with sq can coil, reversing wires in combination with battery ground yields a negative spark output and a lower voltage by ~200 out of 20,000 or ~1%. That might be contrary to my previous comments, but the way I see it today, since I have learned that the front mount sq can coil is start to start (finish to finish) type coil. Such wiring reversal isnt likely to be done with a front mount coil due to access of pig tail.
I contend that there is no significant energy loss, just the thermionic emissions deal, which isn't much either. Temperature may be a few hundred degrees in an engine, where in a vacuum tube it may be 2,000 degrees. Energy = L x I squared. Nothing here with regards to polarity! Example numbers of typical coil are, Energy = 3.75 mHenry x 4 x 4 = 30 mJoules or 30 Watt-seconds
The above pertains to the 8N/9N front mount coils which are start to start (finish to finish) coils. Most (if not all) round can coils are of the start to finish (finish to start) design. Flipping commections on this type of coil actually results in an increase in output voltage (tie point now at points), because with the start to finish windings, the primary voltage now ADDS to secondary voltage. Just the opposite of the 8N/9N coil, where it subtracts. The only situation that I have seen where factory install used this type coil in flipped arrangement is on positive ground Farmall SMTA, so its HV output is primary voltage plus secondary voltage AND is Negative HV spark!
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