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Old 11-30-2010, 03:15 PM   #8
BUBBAS IGNITION
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Join Date: May 2010
Location: SPEEDWAY INDIANA
Posts: 4,148
Default Re: Mallory tech answer to coil/ballast ?

Had a chance to use a current probe today with a couple different ignition coils etc .
After having some problems with various coils we now have our coils made by Andover coil in Layafette Indiana ( usa). We use three different coils being a .6 low ohm, a 1.5 ohm and a 4.0 ohm. All are oil filled canister coils.
The scope waveform shown below is from a contact distributor with ignition points and a 1.5 ohm coil with a 1.5-1.9 resistor in the primary much like we would like to see on a point equiped vehicle. Note that the current is turned on a the left of the waveform and turned off ( ignition fired) at the right. Current is built to a designed limit of a little over 3 amps. (good level for contacts)

The second waveform is the same distributor with no resistor in the circuit, note the rise time increases on the left ( some arcing is shown as well) and the current level is almost doubled ( 6.5 amps).
The spark plug with both ignition coils was firing at 8,000 volts.
The excess heat in the no resistor would have burned the contacts as well and over heated the igntion coil with the lowered resistance.

The same would happen to a electronic ignition controller , however the electronic controller would use a current limiting circuit to control this level and keep the module cool as well as the coil.

As someone said above you really need to use the entire system when buying a aftermarket electronic system.
Attached Images
File Type: jpg points with resistor[1].jpg (43.8 KB, 65 views)
File Type: jpg points without resistor[1].jpg (45.7 KB, 56 views)
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