Another update regarding no sparks on the Canadian carrier when hot. I got the divers-helmet dizzy, remote coil, radio suppression doohicky, and wires off. I've got more questions than answers.
The remote coil says it's a "Standard, 6V, no external resistance required" coil. Lots of oil sloshing around inside. Primary side resistance is 1.4 ohms. I subjected the primary side to a steady 6.4 volts. Current was 4 A, dropping slightly as the coil heated up. I was hoping for a sudden drop in current as the temp rose, but it got up to 70C and was still flowing close to 4 A. So the primary coil is good, I guess.
I also measured the voltage between the secondary coil terminal and the -ve primary coil terminal during the above testing and it also stayed steady at 6.4 V. So the secondary coil didn't go open circuit as it heated up.
BUT the secondary coil resistance is 11 kilohms which seems high. I'm used to seeing around 7 kilohms. Is that a concern?
Also, the wires between the dizzy caps and the the plugs are solid core so their resistance is low as expected, <0.5 ohms, but the wire between the coil and the dizzy is carbon core, with a resistance of 11 kilohms. Is that a problem?
The capacitor is an oldie. It's a Ford piece stamped "6 45", so it may be 71 years old! It tests OK, but it's rated 1 microfarad (confirmed by DMM), which is 3-4 times more than it should be by any standards. I suspect someone used a noise suppression cap by mistake. I'll change it, but I don't think it explains no spark when hot, as I heated the cap with a heat gun while meggering at 500V and it didn't die.
The drivers side points, which initiate the spark, are badly "peaked", with the peak visibly holding the points apart. That can't be good. The points open time on a flathead is so short, I'm wondering if that is the problem?
I need to check if the original ballast resistor that flatheads had in series with the 6V coil is still in the circuit. Or did carriers not have this?
I hooked the radio suppression box doohickey up in series with the coil and passed 4A through it to see if it was reducing voltage to the ignition. It passed with flying colours. No voltage drop, no heating up of caps or inductors.
Sp I'm still wondering what is causing the no spark when hot. If I don't find anything, I guess I need to check voltage drop when cranking to confirm the ignition is getting decent voltage.
Any suggestions appreciated.
Malcolm
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