While waiting for my new coil and ballast resistor from EI to arrive I purchased a generic coil from the auto parts store along with a Dodge ballast resistor.
The cobbled up connections I used with the Military coil were far from permanent or water resistant. I installed the coil and I installed the Dodge resistor in series with the stock resistor.
The input voltage to the coil dropped a couple of volts to 23 which is still much higher than the desired 18ish.
I also connected the ignitor to a solid 28v source as suggested by hammogger.
Everything ran fine that way.
After receiving and installing the new FlameThrower coil and stock ballast from EI (thanks Scott), input voltage to the coil is still 25+ and the truck is currrently running fine, but I wonder if the coil is going to be destroyed soon.
It would appear that the old ballast resistor was fine. The resistance was the same as the new one, now I have a spare.
Perhaps this high voltage reading is just the way my particular voltmeter reacts to the constantly spiking voltage and everything is fine. Maybe the first Flamethrower coil was simply defective.
The charging system is making 28.4 volts which is correct, the ballast resistor is new and the resistance appears to be correct so I can't think of anything else that could be wrong.
For now I've left the Dodge resistor in place in series with the stock one just for an extra measure of coil protection.
I guess I'll try checking the voltage with a different meter and see if the reading is substantially different.
We'll see if this coil lasts longer.
Any thoughts guys?
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Two Tone
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Reading the instructions - a sure sign of weakness and uncertainty.
I have had a voltage regulator fail in a way that allowed the alt to hit 19-20 volts on a 12 volt truck. It killed the coil, ecu, several bulbs, and about 10 hours of my time figuring it all out. The coil didn't quit right away, but a few weeks later I started to have some popping in the exhaust, then hard to start, and eventually no start. Maybe your voltage is a tad high. As I recall, some of the older bosch regulators (at least on air cooled VWs) have an adjustment screw inside so you can set the voltage where you want.
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Seth
71 416Mog, 92 fj80 (worst fuel pig EVER), new 85 300tdt for dad, 2000 KLR650, 84 300td STOLEN!
Maybe your voltage is a tad high. As I recall, some of the older bosch regulators (at least on air cooled VWs) have an adjustment screw inside so you can set the voltage where you want.
Well, at 28.4 volts at speed, it seems to be right where it should be. Certainly not 6 or so volts higher than normal as the input at the coil seems to be.
I still haven't gotten a chance to check it with different meter.
There's an issue here that might explain ignition problems in several 404's recently. The original specs for the military shielded ignition called for very tight setting of the spark plug gap. I'm remembering 0.5 mm, someone correct me? The purpose of the short gap was to protect the shielded wires, the distributor, and maybe even the coil, from high voltage. The sparkplug gap would not allow the voltage to build up because the spark would jump the gap at relatively low voltage.
Then people started opening up the spark gap to 'normal', say .035", the trucks would run better, but the shielded wires would fail. The wires would be replaced, along with civy spark plugs, and the coil could fail and the distributor could arc over internally. (The Pertronix upgrade handled all this just fine because it's in the primary circuit.)
Even 'testing' for spark by removing the wires at the distributor, or watching for spark length at the plug end could toast the wiring. Yeah, I learned this the hard way too. Then I built about a hundred shielded sparkplug wires for one of the dealers, tested many of them on the truck, and learned a lot. Pinz and 404 mog owners would put on the new silicon (aircraft) shielded wires and their distributors would arc over, making it appear the wires were bad. All these interdependent components are a real hassle to work the bugs out of.
When I installed the new NGK plugs along with the rest of the kit I intentionally left the gaps larger than stock. I figured I'd get better performance with the increased capacity of the system and that if the gap proved to be too large for reliable ignition I'd just shorten it.
I hadn't realized the larger gap would allow a higher voltage buildup in the coil.
Methinks I'll shorten the gap to stock and see what I get.
Then people started opening up the spark gap to 'normal', say .035", the trucks would run better, but the shielded wires would fail. The wires would be replaced, along with civy spark plugs, and the coil could fail and the distributor could arc over internally. (The Pertronix upgrade handled all this just fine because it's in the primary circuit.)
This is interesting. I always assumed the stock gap was so narrow to reduce the amount of EMI noise. I've never heard of a wide gap causing stress to the coil and other components, but your explanation of the higher voltage required to jump the gap sounds reasonable.
Is the 0.035" gap preferred if you have a complete civilian ignition? Does it make any performance difference?
I believe the wider gap helps. I think I used about .030. As many other have done, I converted to civilian wires and plugs (keeping original dissy cap), plus Pertronix upgrade, and have had no trouble for years. (Still using the original coil and ballast.)
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