Ignition Coil
Thread Starter
Racer
Joined: Sep 2017
Posts: 334
Likes: 56
Ignition Coil
Hello. My 69 s.b. has and an electronic ignition that was installed about twenty years ago, as to the P.O. work orders, works good no problems.. Perhaps a Pertronix brand, hard to read the work order. It may not make a difference as to my question. I need a new coil due to a crack on the top of the one that is now in the car. Thought of going with a Pertronix one. The vendors list different versions of the Pertronix flame thrower coil. The difference being the ohm. resistance, either 1.5 , 0.6 or 0.32 . Not sure what that means in the actual running of the car and what difference it would make? Can someone explain and advise on which would be good for a stock s.b. Thanks in advance.
Team Owner
Joined: Jan 2007
Posts: 53,648
Likes: 878
From: Southern Cal Ca
St. Jude Donor '22
here you go
https://www.motortrend.com/how-to/ch...ignition-coil/
I would go with the highest volt output so you can run .045 plug gap.
I have a 50k coil, accell, thru resistance power wire using points.
no degradation of points.
https://www.motortrend.com/how-to/ch...ignition-coil/
I would go with the highest volt output so you can run .045 plug gap.
I have a 50k coil, accell, thru resistance power wire using points.
no degradation of points.
Tech Contributor
Joined: Jun 2004
Posts: 20,834
Likes: 959
From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
here you go
https://www.motortrend.com/how-to/ch...ignition-coil/
I would go with the highest volt output so you can run .045 plug gap.
I have a 50k coil, accell, thru resistance power wire using points.
no degradation of points.
https://www.motortrend.com/how-to/ch...ignition-coil/
I would go with the highest volt output so you can run .045 plug gap.
I have a 50k coil, accell, thru resistance power wire using points.
no degradation of points.
Team Owner
Joined: Jan 2007
Posts: 53,648
Likes: 878
From: Southern Cal Ca
St. Jude Donor '22
Respectfully, the 50kV rating is for the dielectric/insulating capability of the windings. It has no connection with the voltage that actually comes out of the secondary terminal. The plug gap width and the cylinder pressure at ignition time determines the peak secondary voltage. The coil secondary voltage merely ramps up until it hits that required voltage, and then clamps at the voltage needed to keep the arc going until the coil energy is depleted. And following the "No free lunch" rule, the wider the gap the shorter the arc time. It's like emptying a five gallon bucket of water. You can empty it fast or slow, but either way you're only getting that same five gallons out.
Racer
Joined: Jan 2016
Posts: 289
Likes: 77
Doesn’t matter if you have a coil rated to a bazillion zolts, it’s only gonna put out what’s required to fire the plug. If the plug needs 10,000 volts to overcome cylinder pressure/ circuit resistance , that’s all it’s gonna draw. A coil that supply’s the energy of a particular engine’s needs reliably is all that’s required.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
5 MOST and 5 LEAST Popular Corvette Model Years in History!
Joe Kucinski
Thread Starter
Racer
Joined: Sep 2017
Posts: 334
Likes: 56
Thanks for the replies. Didn't know what would of been original. Where would a BR 270 coil be available. Was trying to avoid a generic brand, hoped for a bit better quality, even though I'm sure they all come from the same far away place.
1967 Pedal Car Champion
Joined: Mar 2020
Posts: 9,000
Likes: 4,157
From: US-PNW
Whichever coil you install, make sure you have an air gap between it and the manifold of 1/4"-1/2" – coils don't do well with heat.
Instructor
Joined: Nov 2013
Posts: 245
Likes: 77
From: Uhrichsville Ohio
In mpb's situation the coil resistance probably matters. His ignition system is unknown. The electronics probably require a specific resistance range. To low and the system will probably fail. JP
1967 Pedal Car Champion
Joined: Mar 2020
Posts: 9,000
Likes: 4,157
From: US-PNW
The installation instructions for the PerTronix 71181 Ignitor® III Delco 8 cyl specifies .32 ohm or greater.
Melting Slicks
Joined: Apr 2010
Posts: 2,314
Likes: 164
From: Broadview hts Ohio
Post a want to buy here on the forum.
I may even have a good used one. I have a 69 L46 and 72 LT1, both use the same coil.
Also, should be on the large auction site.
Make sure it has been tested good.
Joe
I may even have a good used one. I have a 69 L46 and 72 LT1, both use the same coil.
Also, should be on the large auction site.
Make sure it has been tested good.
Joe
Melting Slicks
Joined: Aug 2011
Posts: 3,072
Likes: 242
Hello. My 69 s.b. has and an electronic ignition that was installed about twenty years ago, as to the P.O. work orders, works good no problems.. Perhaps a Pertronix brand, hard to read the work order. It may not make a difference as to my question. I need a new coil due to a crack on the top of the one that is now in the car. Thought of going with a Pertronix one. The vendors list different versions of the Pertronix flame thrower coil. The difference being the ohm. resistance, either 1.5 , 0.6 or 0.32 . Not sure what that means in the actual running of the car and what difference it would make? Can someone explain and advise on which would be good for a stock s.b. Thanks in advance.
What colour is the top - insulator part of the coil ?
That will tell me whether OEM/replacement type or aftermarket / performance coil and possibly what mfr ?
I went through a coil testing episode a number of years ago and learned that the only domestic (Andover, OH) mfrd coils had a segmented crimp can - (at the top of coil) - irrelevant now - Andover coil plant gone
I bought every chrome segmented crimp can coil I could find - Pertronics coils were not a recommended coil at the time.
As Peters220 said - take your coil to someone with a good (precision) ohmeter and have the primary resistance checked then find an coil with similar primary resistance or greater.
Last edited by QIK59; Jan 9, 2025 at 12:57 PM.
Melting Slicks
Joined: Aug 2011
Posts: 3,072
Likes: 242
I can't be bothered to watch a You Tube video because most of them are a "how to" for dummies / nothing learned.
Can you elaborate what tests are performed and what one actually learns from this video please ? Thank you
I believe the OP coil is functioning fine ?
He just wants to replace it with an appropriate/equivalent coil - asking for assistance in determining what coil he should be looking to buy
Can you elaborate what tests are performed and what one actually learns from this video please ? Thank you
I believe the OP coil is functioning fine ?
He just wants to replace it with an appropriate/equivalent coil - asking for assistance in determining what coil he should be looking to buy
Last edited by QIK59; Jan 7, 2025 at 11:36 AM.
Burning Brakes
Joined: Sep 2016
Posts: 927
Likes: 417
From: Dutchess county New York
I posted that video because it's painfully simple and if you've been at this since October then two minutes and forty three seconds seems a bargain to have your answer.
The primary winding is measured across the two + and - posts on the coil. Polarity doesn't matter. The resistance across those two posts should be in the range of 0.4 ohms to 2 ohms. The secondary winding is between one of the two small + or - posts (doesn't matter which) and the center post. Resistance should show between 6 Kohm and 20 Kohm. The video explains that and how to use a multimeter very, very clearly. I took the time to find it for you because I am trying to help, please take the time to look at it.
Personally, I agree with you about videos but sometimes they are just so obvious it's worth it. This one is really short and very clear.
If you're going to go to a parts store save yourself the trouble and bring a meter and test it right there. There is zero danger to the coil, you won't ruin it or anything. It'll take maybe ten seconds. If they're in that range they're good enough for stock engines, you don't need an expensive super duper ultra spark coil, you just need one that works.
The primary winding is measured across the two + and - posts on the coil. Polarity doesn't matter. The resistance across those two posts should be in the range of 0.4 ohms to 2 ohms. The secondary winding is between one of the two small + or - posts (doesn't matter which) and the center post. Resistance should show between 6 Kohm and 20 Kohm. The video explains that and how to use a multimeter very, very clearly. I took the time to find it for you because I am trying to help, please take the time to look at it.
Personally, I agree with you about videos but sometimes they are just so obvious it's worth it. This one is really short and very clear.
If you're going to go to a parts store save yourself the trouble and bring a meter and test it right there. There is zero danger to the coil, you won't ruin it or anything. It'll take maybe ten seconds. If they're in that range they're good enough for stock engines, you don't need an expensive super duper ultra spark coil, you just need one that works.
Last edited by pigfarmer; Jan 7, 2025 at 01:25 PM.
Melting Slicks
Joined: Aug 2011
Posts: 3,072
Likes: 242
Thank YOU !
I posted that video because it's painfully simple and if you've been at this since October then two minutes and forty three seconds seems a bargain to have your answer.
The primary winding is measured across the two + and - posts on the coil. Polarity doesn't matter. The resistance across those two posts should be in the range of 0.4 ohms to 2 ohms. The secondary winding is between one of the two small + or - posts (doesn't matter which) and the center post. Resistance should show 6 Kohm and 20 Kohm. The video explains that and how to use a multimeter very, very clearly. I took the time to find it for you because I am trying to help, please take the time to look at it.
Personally, I agree with you about videos but sometimes they are just so obvious it's worth it. This one is really short and very clear.
If you're going to go to a parts store save yourself the trouble and bring a meter and test it right there. There is zero danger to the coil, you won't ruin it or anything. It'll take maybe ten seconds. If they're in that range they're good enough for stock engines, you don't need an expensive super duper ultra spark coil, you just need one that works.
The primary winding is measured across the two + and - posts on the coil. Polarity doesn't matter. The resistance across those two posts should be in the range of 0.4 ohms to 2 ohms. The secondary winding is between one of the two small + or - posts (doesn't matter which) and the center post. Resistance should show 6 Kohm and 20 Kohm. The video explains that and how to use a multimeter very, very clearly. I took the time to find it for you because I am trying to help, please take the time to look at it.
Personally, I agree with you about videos but sometimes they are just so obvious it's worth it. This one is really short and very clear.
If you're going to go to a parts store save yourself the trouble and bring a meter and test it right there. There is zero danger to the coil, you won't ruin it or anything. It'll take maybe ten seconds. If they're in that range they're good enough for stock engines, you don't need an expensive super duper ultra spark coil, you just need one that works.
I am glad you understand where I'm coming from.
Also glad to hear the video is only a couple of minutes long - my "concern" was how long would someone have to watch / listen to find out how to clip on a couple of test leads and look at a meter LOL
I am not the original poster (October) I am probably too late to the "party" with my post.
Thank you for your good will and good intention for the OP
I have reached out to someone I was in contact with 11 years ago, who "knew" the quality and origin of most 12V round coils, to pick his brain as to "where things are at" these days for quality coil availability.
If the original poster replies we'll see where things go with our good intentions LOL
Jerry
Burning Brakes
Joined: Sep 2016
Posts: 927
Likes: 417
From: Dutchess county New York
These posts seem to stay around forever and you never know who will be reading what from where.
I'm retired and thought it might be interesting to work at my local AutoZone up front, not in their commercial dept. It wasn't. That part is just a retail outlet no different than a Home Depot or whatever.
I was the one eyed man in the Kingdom of the Blind because I know how to use a meter. I didn't want to be The Man to dispense Advice because I am a putz not a mechanic and don't presume to be. But, if I know something from direct experience I might say something depending on who was asking.
For stock engines, for the most part, a coil's a coil's a coil. I was bored one day and had someone ask about this and was surprised to find one of the new replacements on the shelf was junk. He didn't know how to test it and I imagine that saved him some trouble. Probably a lot.
Meanwhile, I have a couple rolling around on my bench from the Early Jurassic period that have been in and out of a couple of vehicles for one reason or another and they're fine. I wonder if that can happen with the fancy super mega sparker ones ? Probably, quality control is spotty anymore it seems.
I'm retired and thought it might be interesting to work at my local AutoZone up front, not in their commercial dept. It wasn't. That part is just a retail outlet no different than a Home Depot or whatever.
I was the one eyed man in the Kingdom of the Blind because I know how to use a meter. I didn't want to be The Man to dispense Advice because I am a putz not a mechanic and don't presume to be. But, if I know something from direct experience I might say something depending on who was asking.
For stock engines, for the most part, a coil's a coil's a coil. I was bored one day and had someone ask about this and was surprised to find one of the new replacements on the shelf was junk. He didn't know how to test it and I imagine that saved him some trouble. Probably a lot.
Meanwhile, I have a couple rolling around on my bench from the Early Jurassic period that have been in and out of a couple of vehicles for one reason or another and they're fine. I wonder if that can happen with the fancy super mega sparker ones ? Probably, quality control is spotty anymore it seems.
Melting Slicks
Joined: Aug 2011
Posts: 3,072
Likes: 242
A year later ?
Hello. My 69 s.b. has and an electronic ignition that was installed about twenty years ago, as to the P.O. work orders, works good no problems.. Perhaps a Pertronix brand, hard to read the work order. It may not make a difference as to my question. I need a new coil due to a crack on the top of the one that is now in the car. Thought of going with a Pertronix one. The vendors list different versions of the Pertronix flame thrower coil. The difference being the ohm. resistance, either 1.5 , 0.6 or 0.32 . Not sure what that means in the actual running of the car and what difference it would make? Can someone explain and advise on which would be good for a stock s.b. Thanks in advance.
Your car was running fine but you were curious and then after reading ambiguous specs for coils got wondering if your coil needed replacing.
On your latest coil quest inquiry people have given you information on how to test your coil resistance (you had done this already) and answering your question why you need to know the resistance value - let us know when you do something with the assistance given