mrg

First time fail was middle of Nevada 2 years ago .. Having a backup spare coil along as part of the tool kit got things up and running in short order. A couple of weekends ago.........clear sky sun shining......a great day for a round robin 100 mile cruise in the '64.

Idling at a stoplight, the engine suddenly dies (twice). Both times the engine fires back up and runs good. Further up the road.........the engine bucks sharply a couple of times with symptoms similar to the first time imminent coil fail 2 years prior.
​​​​​​What to do but cut trip short. The engine bucks several more times but the coil holds up on the way back home.

Both fails were Accel brand coils. The 3rd replacement coil is an MSD brand unit. .. Hopefully, this one makes the grade.
What is it with these modern day ignition coils only lasting a while (how ever long that might be), then kaput . ..
Just wanted to throw this one out there.
John

Frankie the Fink

Try the MSD 8222 hi- temp, hi-vibration coil.

hedgehead

Accel used to be the go to. Sad.

MelWff

are you using a ballast resistor?

Chuck Gongloff

That's the first thing I wondered.

Are you putting a full 12V to the coil constantly?

Maybe you have one of those special electronic ignitions. You don't mention that.

vettepoor

I went through 3 coils in short order - 2 Pertronix and one MSD unit. I finally went back to ac delco and so far so good. I think it has to do with the poor quality of some of today's parts.

Easy Rhino

That is, what's the status of the wiring to your ballast resistor?

My two thoughts exactly.

Pop Chevy

I would think a full 12V would fry the points 1st.

GTOguy

Voltage needs to be reduced to the coil if running points. If ok, and coils are failing, I have heard/read that the new non-toxic fillers in coils do not work as well as the old stuff. Same with condensers, etc. PCB's aren't always a bad thing. Same with ballast resistors....new ones go bad more often than the old, toxic ones.

69427

The points and coil are repeatedly hit/exposed to 12v while you're driving down the road. A ballast resistor doesn't change that. The ballast merely limits the peak current that can flow through the system, keeping things from fusing open.

dplotkin

Yes, but it is good to point out that the effect of the resistance in the circuit is a voltage drop and why its popular to say "you need a ballast resistor in the primary circuit to drop the voltage" when in fact you need it to limit current, that's why its called a ballast, same as fluorescent lamp ballasts which though inductors do the same thing. Operating a coil at its maximum capability will shorten its life as well as the life of the points having to interrupt the high current.

Dan

ILBMF

When I was 17 years old I kept going through ignition coils after my resistor wire on my '67 Camaro shorted out. I replaced the wire not knowing it was a resistor wire. Ended up buying a Chrysler style ballast resistor and I immediately stopped burning up coils.

cardo0

Coil is a passive or non-wear part. Only thing that can destroy the fine wire windings would be heat whether internal from high current or external from conductive, convective or radiated heat. Well maybe heat combined with vibration. Possible mechanical damage from overtightened bracket clamps to.
Overcurrent would be something like high power capacitive discharge box. Modern performance coils shouldn't need a ballast resistor.
Coil mounting could be in hot location and in contact with hot metal parts.

What I'm saying is something is aggravating the coil to failure as it shouldn't fail in a static environment without added stress.

ejboyd5

Unfortunately, it is becoming more and more common for electrical parts to fail right out of the box or shortly thereafter. It really makes one doubt one's diagnostic skills when the replacement part doesn't cure the problem. I don't remember this happening when parts were made in the USA.

Frankie the Fink

Boy does it ever.

And, for the record, static part or not, I've had several coils fail, many just crapped out or went intermittent, some just started oozing the cooling oil. And I don't over-tighten or abuse them. I've had others last decades...

69427

That seems to be the experience of several here on the forum. It's my guess/speculation that some of the aftermarket suppliers don't look past the static part, and neglect to consider that the coil windings grow (from heat) every time the engine is run, and shrink back down every time the engine compartment is allowed to cool down. This bigger and smaller size cycling has a habit of fatiguing/breaking internal connections if the design doesn't allow for this cycling.

dplotkin

I knew that from my days at the phone company dealing with relay coils. You are exactly right. Ignition coils work hard and handle high voltage in a hostile environment of heat, grease, moisture and vibration. OEM coils were designed to cope with this. At least 3 of my relics are running their original 60+ year old coils and I'd never think to replace them until they quit because of the low-quality of replacements.

Dan

mrg

No ballast resistor in use, the coil was receiving a full 12 volts. Running with a Pertronix 3 ignition module in place of points. Pertronix instructions recommend the P3 receive a full 12 volts for optimum performance using a coil rated at.032 ohms, or greater.

The Accel 8145 coil that was used both times is their 'breakerless electronic coil' (.7 ohms). It would seem ignition coils rated for high performance use should be built able to handle heat cycles, expansion, et al over the long haul without giving up the ghost. Ignition coil manufacturers must be aware of these coil failures.............yet the problem persists.
John

69427

I'm running the (comparatively) youthful original 48 year old coil in my '69 (with an HEI module and no ballast resistance).

I have a few old Delco can coils sitting on the shelf for a backup/replacement, but the dust layer on them keeps growing every year.

GTOguy

I posted this awhile back, but I'll go over it again: a couple of years ago I had to replace an AC Delco ignition coil on a GM HEI from the '80's. Went to the AC warehouse and finally got a good coil after 3 tested bad (ohms out of spec) right out of the box brand new. Made in Mexico.