Took the fairlane out for its first lengthy drive in warmer weather. It was definitely running warmer than before but not outside of the "ok" bar on the gauge. Got a ways out when I started getting random misfiring at idle. From that point things got worse pretty rapidly and I was getting lots of random misses at all engine speeds. I pulled over at one point to let everything cool off with the hood open, the coil was too hot to touch for long. I waited about 15 min and there was slight improvement. I limped it home and parked it.

I thought maybe the ignition was seeing too much voltage due to the 15+ volts the (new) regulator was set at. Prior to this drive I'd reset the voltage at 80*F to just under 15, at the middle of the spec'd range per the manual. I rechecked output today and it was well over 15 again. I reset it to a little over 13, which is much less than spec'd. With all the lights and the blower on, engine at about 1000 rpm, the number was about 12.8. Even with the engine at idle speed, the coil was seeing about 10V.

After a while of running like this I started getting random misfires until the engine quit. I tried bypassing the resistor but it wasn't totally clear whether that helped. I think it might've. Still, I don't know why the coil would need more than 10V. I checked the voltage drop through the points using my ancient Engine Analyzer, and the drop was less than 0.2V. The engine would start up pretty easily after quitting but would run poorly and briefly. Dwell is at 26*, initial timing at 10*, resistor and coil resistances check out correctly. The coil was quite hot again so I swapped it for an old spare I had, the one that was on the car when I bought it. It fired right up but exhibited the exact same symptoms as the other coil.

I haven't tried replacing the condenser this time, but here's what bugs me: resistor, coil, points, condenser, plugs, dist cap and rotor, and wires have all been replaced in less than 1000 miles. The coil, an Autozone unit, has been replaced under warranty once in an effort to rule it out as a bad unit. My other car, a 1962 Chrysler, got all of these components replaced exactly once and has never had a hiccup in a couple thousand miles over several years; its coil is also mounted laying down on the engine. I don't want to believe that all of the ignition parts I can buy at the local store are unreliable junk.

Any ideas what I'm missing here?

1954 Crestline Victoria 312 4-bbl, 3-speed overdrive

I have not yet tried the Chrysler's Accel coil in the Fairlane because, to be honest, I'm afraid to mess with a good thing. I'm still planning to try it as a last resort. Wanted to put in another update before I proceed though, just in case...

Spent more time fooling around with it today, pretty much re-checking everything. It so happened that everything under the hood was exactly 75*F according to my temp probe, which is the exact spec the manual cites for all resistances, so I checked them. Ballast: 1.3 ohms. Coil primary: 1.3 ohms. Coil secondary: 8350 ohms. Coil current draw (engine stopped): 4.15A

Just for grins, I checked the Chrysler at the same time. I was surprised to find its ballast resistor read just 0.8 ohms.

Anyway. Started the car, drove it around to warm it up, everything's peachy. Got to the usual point where it would start up but not run. Swapped in a different condenser, no change, and inspected the points, which looked OK. No change. Only thing that makes any difference is bypassing the resistor, which makes it run great. Today the coil was not much over 100* when the problems started happening. When I bypassed the resistor, its temperature climbed substantially. Charging voltage was 14.5V; volts to coil post-resistor were around 12.

I noticed that I could thin the idle mixture out a half turn at idle in gear without any noticeable change in engine running, as long as the resistor was bypassed.

I am very suspicious that this coil is bad. It seems plausible that when the coil gets enough heat in it a short develops in the primary windings resulting in a weakened spark that can be "corrected" by boosting the voltage supply. It also seems plausible, as some of you have suggested, that the ballast resistor isn't doing its job and reducing the current sufficiently. Both components show basically the same resistances when the system is malfunctioning as when it is working properly, ALTHOUGH I think it is worth noting that the coil primary resistance DROPS a couple tenths when it gets warm while the secondary resistance climbs up about 1k ohms.

If the coil is bad, either a component external to it caused it to fail (such as the ballast resistor) or else the design of the particular coil I bought is not suited to its environment on the Fairlane's engine. Since I don't understand why the coil was getting so hot in the first place, and I cannot find any conclusive, measurable faults in specific parts, I'm left in the unenviable position of having to assume that at least one of the "new" parts is bad out of the box without any guarantee that the next I buy will be any better.

Should the resistor be knocking that 14.5V down below 12?

1954 Crestline Victoria 312 4-bbl, 3-speed overdrive

OK. The car that is in your garage thats works is NOT the FORD it IS the CHRYSLER. Do the same test on it and compare the results.

The VOLTAGE to the coil ( Ford or Chrysler ) should be the same. Go from there.

If the car quits and you have to bypass the resistor to get it to run, the resistor is opening when it gets warm. Bypassing the resistor will heat the coil. Check the resistance of the resistor when the car dies, you will probably find it open.

John - "The Hoosier Hurricane"