I've got a 292 y-block that I've been having some issues with. When I got the truck it was hard starting, running rough, flat spot on acceleration,and would just die on test drives. I thought it was a overfuel/ carb issue and replaced the holley 600 with an edelbrock 500. The truck came alive and ran better than it had since I had it. I took it around the block and it still just died mid driving. I popped the hood and saw no fuel pressure on the gauge. I looked at the tank and it was pretty nasty. I thought it was picking up debris from the tank and getting clogged. I replaced the tank and fuel lines. I took it around the block and the same thing happened. I was messing around under the hood and noticed the coil was super hot. Now what I'm thinking, is the coil overheated and the truck died. I replaced the coil and it's still getting really hot after a few minutes. The distributor is a later style, not a load-o-matic. It had been converted to a pertronix ignitor 1 ignition by the PO. The coil is a flamethrower 1.3 ohm. I have 13v on the battery when running and 14v to the positive side of the coil. The coil is wired to the ignition switch with no resistor wire. However, the PO did a terrible job wiring the truck. He had multiple ground straps sitting on top of completely painted steel. I have a cleaned up a connection from the motor to the body, and the distributor hold down to the motor. I was going to change the cap, rotor, plugs, and wires. Any other ideas? Maybe add a ballast resistor to get the voltage to the coil at 12 vs 14? Move the coil off the motor? I'm running out of ideas.

Another issue that could be related. The truck might have a parasitic drain on the battery. Every so often I'll have to put it on the battery charger because it won't turn over. The generator was going out, so I replaced it with a gm 65 amp alternator. The battery is less than a year old. Thanks.

 

In most cases when the coil gets hot it need a resistor, but you need to find the wiring diagram for the pertronix ignitor and do it right before you fry the whole system.

 

Pertronix makes a few different coils, and a few different Ignitor modules. Be sure it's a 1.5 ohm coil if using the Ignitor 1, the ballast resistor (pink wire) can be bypassed to take advantage of higher voltages and make for a higher output ignition. Make sure the rest of your ignition is top notch shape, cap, rotor, wires, as the higher secondary voltage output will start arcing to ground or crossfiring at the distributor. When you get into Ignitor 2 and higher end modules, these use the low ohm coils. Don't try to use a 0.6 ohm coil alone with the Ignitor 1 module.

Assuming you have the Ignitor 1 make sure the primary ignition circuit has a total of at least 1.5 ohms. More is not better, but make sure the coil is at least that and should be in good shape. If you leave the stock ignition "pink wire" installed that would be OK, but spark output would be reduced. A little bit of Ohm's Law to help guide you, an Ignitor 1, assuming that's what you have, will tolerate up to about 8 amperes. Figure your primary ignition circuit resistance and running voltage and see what you come up with. A V8 coil is not "on" but roughly 66% of the time. Since the dwell is fixed it is a compromise between a reasonable saturation time at high RPM and at idle.

Have used the Ignitor 1 and Flamethrower 1.5 ohm coil arrangement many years in my Y-block at full battery voltage. Coils get hot how hot is "too hot"? That is something you'll have to decide.

 

The instructions on the coil state to remove the resistor. I traced the line back and don't have one in place.

Using ohms law I'd be running 9.33 amps based on running 14v and a 1.5 internally resisted coil. That number will obviously be a slightly lower due to the slight resistance in the non resistor wire. If I bring it down to 12v I'd be at 8 amps. After a few minutes the coil gets too hot to hold on to. The issue for me is it overheating to the point the truck dies.

 

Right - but an ignition coil isn't "on" all the time, a V8 has about a 66% duty cycle. Multiply 9.33 by .66 and should be good to go, just over 6 amps. Incidentally this is why the ignition switch should never be left in the "RUN" postion without the engine actually running. If the contact points happen to be closed, or one of the lobe magnets aligned with the sensor, constant current will flow through the primary circuit and ignition coils will fail after several minutes. Maybe an hour or so? Can burn up points too, and roast a solid state module. The Ignitor 2 has protection circuitry to prevent this.

I just got back from a test drive, adjusted idle mixture in the garage and was reminded of your post and checked, the coil does get very hot. Still. Some of that is from engine heat. I use their Epoxy filled coil. If it got "sizzle" hot, like when making pancakes, I'd start to worry. I carry a spare coil, points, and condenser. I've been running it this way for 15 years or so. Find something else to worry about, if you have a vintage Y-block I'm pretty sure you're covered. /s

 

I'll have to see if it sizzles. If the coil isn't overheating, then I'll have to come up with another possible reason the truck dies mid test drive and is hard to restart until it sits. Thanks for your input

 

Have you checked for spark at the time it fails on the road? I mean, it isn't like ya got anything else going on at that time, right? /s

Pull the coil wire from the distributor and hold it about 3/8" from an intake bolt or something like that. Ground. Check it right away, under the same heat conditions. Crank the engine over and look for a fat, hot spark. With a Pertronix it should be kind of bluish-white. A thin orange spark is no good. I noticed some module manufacturers, competitor products, provide a packet of heat sink compound (dielectric) to fill any air gaps. I don't know if a Pertronix module can be intermittent like that. Maybe. Could try blasting it with some freeze spray.

It is at least possible for an ignition coil to go intermittent. Do you have another one you could try?

 

Maybe I missed it, so I will throw some things out there for consideration. When the engine quits, have you looked down the carburetor to see if there is gas in there? Have you tried pumping the throttle linkage to see if there is gas squirting out of the accelerator pump nozzles? Obviously the problem is either fuel or spark related. To be sure, I would completely eliminate the fuel delivery component. That would mean the carburetor, fuel pump or fuel lines. Also, make sure there is no possibility of vapor lock (fuel line near the exhaust?). Have you opened up the float bowl to see if there is any garbage inside the carburetor that could be plugging up one of the fuel circuits?

Once you are absolutely sure the fuel system is all good, then concentrate on the electrical system. I installed a complete Pertronix setup in my 292. This included their Ignitor module, coil and spark plug wires. I noticed a blue spark on the top of the coil when the engine was idling at night in a dark garage. I called Pertronix and they resolved that issue by sending me a new coil. A few years ago, MSD had problems with a batch of Blaster coils. My point is that there can still be issues with your coil. Since they usually can not be repaired, it might be worth swapping in a new one that meets with the approval of the folks at Pertronix. They did offer up several suggestions that helped with my installation and it works to perfection. My experience is that you do not run a resistor or ballast in the ignition circuit if you have a Pertronix Ingnitor in your distributor.

Hopefully you can get a handle on this sooner rather than later. Stuff like this can be frustrating.

 

Pertronix Ignitor is pretty much "Go" or "No Go", here's some troubleshooting tests: Pertronix Faq

The unit itself doesn't like high resistance. Don't remove the bare copper ground wire on the breaker plate. The resistance limit is 0.2 ohms measured from the Pertronix base plate as installed to the negative battery post. Zero test leads and subtract the meter lead resistance indicated to get an accurate measurement of the actual ground path resistance.

 

Thanks guys. I'm going to have to test a couple of these ideas out this weekend

 

I had the same problem on my ‘59! My coil would heat up to 160 degrees! After many tests, it turned out to by my distributor. The gears were rounded on 6 of the 8 cams. So the points would fuse and back feed the condenser and overheat it and blow out, so the coil would over heat. Installed partronix electronic ignition. Installed it in my high school parking lot. Never had another problem with it.

 

What gap are you guys running on your plugs? The manual calls for 0.028 to 0.032. I saw some posts that some guys say they are running 0.040 with pertronix. The plugs that I just picked up are factory gapped at 0.043, which is what the truck is running with right now. Possible issue?

 

There's different schools of thought on this. One thing everyone agrees on, the spark plug gap affects the coil firing voltage, can see this on an ignition oscilloscope. Wider plug gaps or at least too wide can cause the coil voltage to spike excessively high before firing, "more" is not always better. A typical round OEM ignition coil is capable of about 20,000 volts. It only takes about 8 or maybe 10k volts to fire at idle, the rest is reserve capacity in the coil.

The ignition coil only provides the voltage that is needed to fire the plug gap, and no more. Installing a higher voltage output coil doesn't change this. Higher compression, heavy loads, worn electrodes, and leaner fuel mixtures requires higher firing voltages.

There's another air gap in the ignition system that also directly affects the firing voltage though, this is the length of the rotor tip, or the air gap between the distributor terminal and rotor tip inside the cap. Smog era rotors, same part #, have quite a bit wider gap inside the distributor cap. Whether this is a good thing in points style distributors, probably not. Ford sometimes changes parts, without changing the part number. B7A-12200, the gap can vary widely.

What I'm getting at is all this stuff has to work together as a system. Now some ignition guys claim that the proper spark plug gap is governed by cylinder head design and the layout inside the combustion chamber, and this does not or should not be changed, that nobody has demonstrated more power by wider gaps, yadda yadda.

If the plug gap is opened up it will place more strain on the other ignition components including the coil and increase the likelihood of misfire or crossfire or arcing to ground. When GM first introduced the HEI they were using .060" plug gaps and stuff started burning up, and they had to back off. Examine the rotor closely, look for evidence of arcing, right around the spring contact. Voltage will blast through the bakelite or plastic straight to the distributor shaft. Carbon tracks inside the cap, etc. The idea here is to put the spark at the plugs, and nowhere else.

It's worth experimenting with plug gaps, don't get carried away. While it might seem okay at idle, what's it doing under load, up a grade at high speed or when towing? .040" seems to work well in my Y-block with a high output coil. The way aftermarket high output coils increase the spark intensity is by running at full battery voltage instead of a dropping resistor or ballast, and a different turns ratio in the primary and secondary windings. So you can open it up a little, though if it's a point style distributor and cap, this is limited. If you could get by with .055" gap, that would be ideal maybe, more power to ya.

The older points distributors have much closer spacing or diameter between terminals, if everything isn't just right with the components there can be misfiring and arcing to ground. Notice when electronic ignition came out, they went to big *** diameter caps. This is why. I had to find an NOS long rotor to keep everything tamed down inside and outside the points style distributor when running a hot ignition coil at full battery voltage.

They didn't necessarily use resistor plugs or resistance plug wires in those days. These raise the firing voltages too. I use resistance type plug wires, but non-resistor NGK plugs, a step down in heat range. Like I said, everything has to work together as a complete system, when changing one thing in an ignition system, it can change something elsewhere. In most cases genuine Motorcraft ignition parts are what you want, there is a difference in materials and QC in things like distributor caps and rotors, wires, points, condensers etc. If you have access to an ignition scope this can save MUCH head scratching and lead to a good sharp tune. A lot of guys will experiment with side-gapping, or indexing plugs too. I don't know if it affects power too much but indexing does seem to improve idle and exhaust note. Fun stuff!

 

I went out and changed the plugs (gapped at 0.040), cap, and rotor. The plug wires they gave me were too short, so I'll have to swap them out later. I had the truck running and the coil was running between 125-130 degrees via an ir thermometer. The intake was 175-180 for comparison. Below is what the old cap/ rotor looked like.
Back to the drawing board.

 

Both the rotor and cap look to be in pretty good shape? Not sure they are ready for replacement.

See if you can find a hot rod shop or "old guy" with an ignition scope analyzer. If there's a defect in the ignition it will probably show that in about 30 seconds. How does the spark look? Ground an extra plug and crank the engine over. Or use one of those gap testers. With an Ignitor, it should be a fat, whitish-blue good spark.

Coils do sometimes fail intermittently, they can get shorted turns for example in either the primary or secondary winding. Sometimes this can be hard to spot, because the voltage output won't be reduced, just the time or duration of the spark itself, and reduced performance under load. They are on the road to failure though. Things like ignition coils and condensers can only be tested at normal operating temperature (HOT) for a valid test. Coils get hot, that's what they do, especially high output specialty coils run at full charging system voltage of 14.x

I'm telling you, you're probably worrying about something that might be normal. Check your valve lash lately? Made sure the upper valve train, the rocker arms are getting plenty of oil on both sides? Make sure manifold vacuum is good, float levels in carb are set right, and distributor advance is working as it should etc....