sunflower 1972

I've been chasing a random and extremely intermittent engine popping under hard acceleration in the 3000 to 4000 rpm range ever since I installed a new intake manifold and MSD Blaster 2 coil about a year ago. Drove it all summer and fall until I started on my winter project of replacing the original heads with some Edelbrock aluminum heads. Finally got it running and running good about a month ago, hoping in some way the old heads were contributing in some way to the random popping. No such luck. Rechecked timing and dwell, all good. Searching this and other forums, found others having the same issue and discovered ignition coils breaking down. So, I bought 3 new coils. A new MSD, an Acell,(matched the color of my C3), and a Delco U505. Installed the Acell this morning, no start. Checked connections, still no start. No problem, I have the NEW MSD. Installed that one, STILL no start. Installed the old MSD, fired right up. OK, well I can't drive and test it out for the popping with THAT one, because that's the one that I suspect is causing the problem. Take that one out and put in the new stock Delco unit and go for a test drive BINGO, no more popping! Just nice smooth pulling power thru the entire RPM range. Now, just need to regap the plugs back to .035 and enjoy driving it. AND, I'll be returning the "NEW" coils tomorrow.

Big2Bird

Yep. The latest batch of Blaster 2 coils are absolute crap. They leak, they fail, they get hot, they cause headaches.
Good old stock Delco coils are still the best. ZERO gain from "performance" coils. HEI is the only upgrade, but no performance gain, just reliability from point free operation.

sunflower 1972

Big2Bird, you are right. And I should have known better in this day and age, being in the GM parts business at the dealership level for 45 years. But, even I get sucked in at times by the marketing and hype.

CanadaGrant

Is it possible that the new after market coils require a full 12 volts unlike the original which uses the reduced voltage supplied by the ignition resistor wire on the early C3's?

sunflower 1972

That doesn't make sense because the engine ran pretty good with the MSD Blaster 2 that I installed last year. Just the random popping. I'm just AMAZED that TWO BRAND NEW COILS from TWO DIFFERENT COMPANIES were defective RIGHT OUT OF THE BOX! But, perhaps I expect too much. After all, it's 2017, not 1977.

BLUE1972

I'm not supprised,

the child building coils in ****-BONG China just slaps on the label for the current order. They are all the same crap..

Big2Bird

All coils use 12 volts. The resistor wire limits the current to 4 amperes.
There is an ignition stickey at the top that will explain it in greater detail.

Sigforty

I had a lot of issues with coils until I put in the MSD high vibration one. I belive they are built in a different place from the other blaster 2 coils. They use epoxy so you dont have to worry about oil leaking out.

stingr69

Been there, done that. Aftermarket coil installed came with occasional intermittent engine misfiring. Put the original antique Delco coil back in and never had a hiccup after that. The HEI is a solid piece that just needs a recurve. NEVER AGAIN!

Metalhead140

I had one of those fail about 2 weeks after install last year. I put the 15+ year old blaster 2 (that I replaced purely as a preemptive measure given its age) back in and all was good. I swapped the warranty replacement high vibration coil into the car about a month and a half back and haven't driven it a lot since, but last time I drove it it was breaking up at higher rpm and load. I'd put that down to running rich due to an exhaust leak (which it is), but perhaps I should check swapping the old coil back in...

NewbVetteGuy

I was looking at LS coils and aftermarket LS ignition coils and the aftermarket ones still have huge quality control issues, until you get into the really expensive ones made like 20+ lbs of boost the GM Delcos seem to be the way to go.

Went with a set of LS3 generation truck coil takeoffs from Ebay: $125 for 8 coils, bracket, and wiring harness- no plug wires & lots of rust.




Adam

gkull

Not all ignition coils àre created equal the super magnetic core makes superior. I bought these back when they were made by crane cams. FAST seems to have bought the product because they saw the superior design

https://www.summitracing.com/parts/fst-730-0291

ezobens

Aftermarket manufacturers don't have to adhere to the same stringent specs as the OEMs so their reliability is all over the map.
Unless the OEM parts can't support your particular build, I'd stick with them.
Just my .02

Big2Bird

What is a super magnetic core?

pauldana

yes and no... the resistor makes what is called a voltage divider circuit, in doing so, yes the VOLTAGE is DROPPED on the point side of the wire. And yes, of course this limits current and current is a calculation of voltage and resistance,
V=I*R

69427

What's the voltage at the coil C+ terminal at the start of dwell?

gkull

When the Crane Cams ignition coils first came out one of the car rags did an article on the use of Super Strong Rare Earth Neodymium Magnets. it vastly decreases charge and discharge time. Less heat production....... they aren't even oil filled to conduct the heat away. Just a great compact coil.

They work really well in high powered multi spark ignition systems or even your mild stock motor.

pauldana

Before the points close it will be 12v~ once the points close and a load is produced the voltage divider circuit functions and there is an instant drop in voltage... this is how a voltage divider circuit works

I understand how you see this...
I was an electricteonics engineer for well over 20 years
EE CSUN

Big2Bird

The thing Mike and I convey is that in the Kettering ignition system, the ballast is there to control the amperage, not the voltage, which is why when "they" read the voltage after the coil is charged, it's kinda irrelevant.
My Sun machine has an ammeter and a volt meter, and a variable ballast resistor. I close the points and set the resistor to 4 amperes.
If I run the distributor, the amperage drops to 2 amperes, because the meter can't keep up, and reads an average of 2 amperes, but it's really pulses of 4 amperes.

69427

Paul, I'm in no way trying to appear disrespectful to a fellow electrical engineer, but the bolded part above is wrong. An ignition coil is an inductor, not a simple resistor. Freshman circuits class says that the current through a resistor can change "in an instant", but the current through an inductor does not and cannot. When the points close, or the transistor turns on, the entire supply voltage (12v in this case) is impressed upon the coil (inductor). There is no instantaneous current flow through an inductor, so there's no IR drop across any circuit ballasting resistance at the start of dwell.

The ballast resistor limits the peak current through the coil and points, but it does not limit the peak voltage that the coil and points see.

EE UI