Welp, I seem to have melted (exploded?) my ignition coil. Trying to get this '47 216 started for the first time in years. I am going to 12v so installed a Pertronics flamethrower. Been cranking on her a couple of times, then letting the starter rest a few minutes, then repeat, in trying to get fuel to the carb. I wasn't turning off the ignition between tries though, and after about 30 minutes the coil just exploded in a spray of steam. Whatna' heck?
Is there a different coil setup I should be using? It seemed to work otherwise, as the engine is trying to start on ether.
Do you have a ballast resistor? Some high performance coils require 2 ballast resistors. Since we don't know how your coil is wired, we can only make a few guesses, but let's start here.
As a side comment (and this is a personal opinion) you should avoid anything with Pertronix on it.
~ Jon 1952 1/2 ton with 1959 235 | T5 with 3.07 rear end
There are two kinds of Pertronix units- - - -the ones that have had a catastrophic failure, and the ones that are going to. What's wrong with using points that have powered millions of vehicles over billions of trouble-free miles? Not everything "new and improved" is actually a good thing to do. Since Peertronix does not have a safety circuit for people who leave the ignition on with the engine not running like a GM HEI system does, it's most likely toast. Don't bother buying another one.
If you have to "try a while and rest" you're not ready to start cranking on that engine. Get it mechanically sound, timed, and tuned properly before you start abusing the starter. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Points work good for me..... I usually change them after 4 or 5 thousand miles and never had a problem. I tried one of those coils with points and it started to get hot so I removed it and used a standard coil.
Jon - no resistor - so that's going to get picked up and put in this morning. When I was reading up on 12v conversions some were saying I needed it, some were saying not. I guess I do!
Carl - not a full Pertronix setup. Everything else in my distributor is factory. In converting to 12V I just asked at my FLAPS for a generic 12v coil and this is what they handed me. Learning as I go I guess...
Jerry- It must be nice to do everything right on your first try, but I'm not that good. The entire head and valve train has been disassembled and polished, carb rebuilt, and timing is set... but I can't "tune" it until I at least try to fire it up. I was cranking on it to verify I was getting fuel pressure from the new mechanical pump. It was firing and only running for a second or two but not idling. And it's kind of hard to bottle feed a carb with a floor starter.
Valve timing and adjustment, initial carburetor settings, and ignition timing can all be done without cranking the engine. It's not necessary to turn the ignition switch on to check compression. A simple toggle switch upstream of the ballast resistor can be used to interrupt voltage to the coil, and a short pry bar between the firewall and the start pedal linkage puts all the starting controls in one place under the hood. Backing the fuel pump attaching bolts out a couple of turns and moving the pump housing up and down by hand will verify that it's working properly, and also fill the carburetor float bowl without cranking the engine. Maybe making a living doing all this stuff for 60+ years makes me "Captain Obvious"- - - -or maybe it's just plain old common sense! Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Ignition coils normally don't explode, but if you're running 12v through any automotive coil for prolonged periods of time and if your points are closed, that's a recipe for trouble. Automotive coils weren't designed for this. They're all about a low voltage primary winding (which when energized will instantly form a magnetic field around the coil), a secondary winding (which when surrounded by this field will produce the high voltage needed for your spark plugs) and the collapse/restoration of that primary magnetic field which is regulated by the points and the condenser...and this happens very fast. Fractions of a second fast, even in a 216. The high voltage energy travels through the rotor/dist cap and coil and spark plug wires and is transmitted to each cylinder when needed to complete the combustion process. The ballast resistor keeps a 12v coil limited to somewhere between 7 and 9 volts (depending entirely on who made the resistor). It lets your coil stay cooler, last longer and operate more efficiently. In basic terms, I think that's about it, however it does get much more complex the deeper into the forest you go. Jerry and about a half dozen people on this forum can take you there, but with a 216 I don't think you need to spend too much time on it.
In your case "Flamethrower" seems to be an apt name for another Pertronix mess. Very glad you weren't standing next to it when it failed and did its flamethrowing. Definitely use a ballast resistor and definitely try to find a more stable coil. As far as I know, MSD coils are still made in the USA, but that's the only one I'm aware of that still is (or may be). You could probably find a decent old or maybe NOS coil on eBay. Good luck!
~ Jon 1952 1/2 ton with 1959 235 | T5 with 3.07 rear end
The various types of "high output" coils all work the same way, regardless of how the advertising department for the manufacturer spins it. They increase the current flow in the primary windings to develop a stronger magnetic field, and a higher open circuit voltage in the secondary winding which fires the spark plugs. That's fine, as long as there is an electronic switching circuit in the mix that's capable of handling increased primary current. Points can't do that- - - -no matter how efficient a condenser is used to protect the points, they can't handle current flow more than 5 amps or so. Most "flamethrower" type coils run primary current in the range of 15 amps or a bit more- - - -three times what a set of points should handle. That's OK if you plan to make a few passes down the drag strip, or spend one night of going around in circles, and then change the points, but doing that with a daily driver doesn't make good nonsense. With the engine running with a "12 volt" electrical system, a voltmeter at the ignition switch side of a "resistor needed" coil and a point-type distributor should see 9.5 volts or so to keep the points function ing properly. The upstream (ignition switch) side of the ballast resistor in a system like that will be around 14.5 volts with a good charging system.
BTW- - - -a clean, properly-gapped spark plug fires at about 8KV, so that "50,000 volt" flamethrower will never get to develop its high voltage- - - -once the spark starts flowing across the plug electrodes, it's impossible for the voltage to rise above what was required to ionize the gap and start the skark flowing. Buy a plain old OEM coil and keep the rest of the money you would have wasted on the fancy coil for a few cases of beer! Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
