Coil Voltage ???

[IndyA]

While trying to isolate a motor problem in my '29 coupe, I dug into a box of parts that came with the car to get another coil to install... It was marked "12V"... put it on. Later resolved the problem (not the coil) ... Question.. can I keep this one on the car even though the car has the traditional 6 volts system ??... Thanks

[katy]

Check the resistance of the primary windings, it they are around 1.5 ohms you can use it with a 6 volt system.

[IndyA]

Katy... thanks for the fast response... do I put my multi-meter on the negative coil terminal and ground to test the resistance of the primary coil ???? IndyA

[California Travieso]

Katy . . . How do you test the secondary winding, and what is the value? I got a coil at a Swap Meet and Googled some articles on testing coils but they didn't give the values for either the primary or secondary windings.

David Serrano

[40 Deluxe]

Originally Posted by IndyA

Katy... thanks for the fast response... do I put my multi-meter on the negative coil terminal and ground to test the resistance of the primary coil ???? IndyA

Connect your ohm meter leads to the primary terminals, not ground. Disconnect the wires first.

[eagle]

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If it throws a good spark it is just fine to use.

[katy]

Connect your ohm meter leads to the primary terminals, not ground. Disconnect the wires first.

Ditto

Regarding the resistance of the primary windings,
6 volt coil should be aprox 1.5 ohms.
A 12 volt coil that uses an external "ballast resistor" is usually also around 1.5 to 1.7 ohms and will work fine on 6 volts.
Some 12 volt coils have a built-in resistor and are usually around 3 ohms.

[gustafson]

Some say you should only use a performance coil. I am not one of them

[Purdy Swoft]

I don't remember ever hearing anybody say that a person should only use a performance coil . It is a matter of choice !!! Before trying the Pertronix flame thrower coil , I had never heard of anybody using one on their model A . The Pertronix flame thrower coils are offered in both 1.5 and 3 OHM like most other coils. I prefer the 3 OHM coil on 12 volts simply because it doesn't require the use of a ballast resister . Resisters don't look original on the model A and they get very hot.. I personally could care less what type coil that a person uses . Being my own man , I make my own choices . If the type coil that I use didn't preform flawlessly I wouldn't use it .

[Purdy Swoft]

Who said that anything was wrong with original model A coils . If in good condition original coils are probably better , stronger and of course prettier than most standard over the counter coils . I prefer performance coils on some of my cars . There is not necessarily anything wrong with original . Some are interested in upgrades. Some onlywant original for show purposes. A lot comes down to whether the car will be an ocaisional driver or a mostly
trailored show car . Its freedom of choice , if thats over your head , too bad !!!

PS If you pay close attention , you may learn something !!!

[gustafson]

HaHa If everyone would pay close attention we would all learn something!!!

[Cape Codder]

I have read that the Pertronix flame thrower coil or similar product which produces too much voltage, therefore, wearing the points much quicker than a regular Model A Coil. has anyone experienced this?

[gustafson]

We have removed such coils here because of this issue, and cross firing between cyls due to excess voltage leak

[Purdy Swoft]

The mention of 40.000 volts scares some people . I'm still running the same original style points that I got from Brattons in 06 when I installed the coil .

[29er]

Originally Posted by Purdy Swoft

The mention of 40.000 volts scares some people . I'm still running the same original style points that I got from Brattons in 06 when I installed the coil .

Roger that. I've got > 7,000 miles on my coupe with a Pertronix Flame Thrower 1.5 ohm coil and original points. "Power you can feel in the seat of your pants"!

[Tom Wesenberg]

Originally Posted by 29er

Roger that. I've got > 7,000 miles on my coupe with a Pertronix Flame Thrower 1.5 ohm coil and original points. "Power you can feel in the seat of your pants"!

Yep, that's the exact experience a worker had at the yard where I worked. Someone wired the coil to the driver's seat spring, and the driver felt the power in the seat of his pants. True story.

[Mike V. Florida]

The voltage and current at the points is the same no matter what coil or points you use if the resistance of the coil is about 1.5 ohms for 6 volt and about 3 for 12 volt. The 20 or 40.000 volts do not go through the points.

[Purdy Swoft]

Originally Posted by 29er

Roger that. I've got > 7,000 miles on my coupe with a Pertronix Flame Thrower 1.5 ohm coil and original points. "Power you can feel in the seat of your pants"!

Thanks 29er for telling it like it is .The flame thrower coil gives power that a person can feel and we ain't talking about getting shocked . Some can't seem to understand this and it scares the hell out of them . The spark comes from the coil . Hotter spark in most cases increases power .

[Purdy Swoft]

Originally Posted by 2831A’s

Coils, brakes , FP regulators over and over. Whats wrong with stock

You obviously have a lot to learn, Manners being number one . Reading all of your posts doesn't really share any model A information that could be useful to anyone , whether it be original or aftermarket upgrades . Your ignorance and rudeness is obvious.

[gustafson]

"Hotter spark in most cases increases power"
We'll have to assume this is opinion. Are you able to cite an independent writeup from the automotive engineering trade?
Does an increase in spark to 80,000 make even more power?

Power is determined by the CR and cam specs. Once the charge is lit, no matter the voltage, the flame front is the same.
Readers are being led to believe that the stock system is inadequate.

See #12

[Corley]

Originally Posted by Purdy Swoft

The flame thrower coil gives power thatr a person can feel and we ain't talking about getting shocked . Some can't seem to understand this and it scares the hell out of them . The spark comes from the coil . Hotter spark in most cases increases power .

Sorry to be so blunt, but that is a load of crap! Sure, a weaker than required spark will cause poor engine performance, but once you have reached the threshold of adequite spark, adding more will not increase power, period. With the low CR of the model A engine, the stock coil will provide every bit of spark needed for full power output.

On this same subject, and in response to a post saying any coil will not be any harder on the point than any other coil, not so. It all depends on the resistance and inductance of the primary side of the coil matching the condenser. If you use a coil with very low resistance, say 1.0 ohms, it will draw a lot more current than a coil with say 2.0 ohms, and the points will probably not be happy. It's simple electronics, not mystic voodoo.

[29er]

Originally Posted by Tom Wesenberg

Yep, that's the exact experience a worker had at the yard where I worked. Someone wired the coil to the driver's seat spring, and the driver felt the power in the seat of his pants. True story.

HAHAHAHA. Well see, if he had been wearing his "Depends", that wouldn't have happened! Let that be a lesson!

[Purdy Swoft]

I don't need a cite from anyone . I make my own determination . You and some others act like you have never heard of a performance coil . Performance coils do work or they wouldn't have been available for all of these years. The Mallory bee hive coil was probably available in the times that model A's were in regular use or built . I have used the 30.000 volt Bee hive coils and they give a good boost as well . You mention compression ratio and cam specs , Those mods are certainly not the only things that can add power and effect performance . You mention when the charge is lit . The coil is the major part that lights the charge. Your ignorance and rudeness is pathetic . It is obvious that all that you and your buddy from the other side are trying to do is stir up trouble and disagreement . It seems that all that it takes is the mention of the coil that I use to set off your bull $hit. Personally I could care less what type coil that a person chooses to use . You keep mentioning original parts . Original coils are no longer easily found . Most are using aftermarket coils that are available from vendors . Most replacement coils fail to jump a 10.000 volt gap with my coil tester . Nobody has suggested that you should use a flame thrower coil, you would probably hook it up wrong anyway .

[Corley]

Originally Posted by Purdy Swoft

I don't need a cite from anyone . I make my own determination . You and some others act like you have never heard of a performance coil . Performance coils do work or they wouldn't have been available for all of these years. The Mallory bee hive coil was probably available in the times that model A's were in regular use or built . I have used the 30.000 volt Bee hive coils and they give a good boost as well . You mention compression ratio and cam specs , Those mods are certainly not the only things that can add power and effect performance . You mention when the charge is lit . The coil is the major part that lights the charge. Your ignorance and rudeness is pathetic . It is obvious that all that you and your buddy from the other side are trying to do is stir up trouble and disagreement . It seems that all that it takes is the mention of the coil that I use to set off your bull $hit. Personally I could care less what type coil that a person chooses to use . You keep mentioning original parts . Original coils are no longer easily found . Most are using aftermarket coils that are available from vendors . Most replacement coils fail to jump a 10.000 volt gap with my coil tester . Nobody has suggested that you should use a flame thrower coil, you would probably hook it up wrong anyway .

Purdy, you know it all, so there is no point in even responding. Good luck...

[Purdy Swoft]

Originally Posted by Corley

Sorry to be so blunt, but that is a load of crap! Sure, a weaker than required spark will cause poor engine performance, but once you have reached the threshold of adequite spark, adding more will not increase power, period. With the low CR of the model A engine, the stock coil will provide every bit of spark needed for full power output.

On this same subject, and in response to a post saying any coil will not be any harder on the point than any other coil, not so. It all depends on the resistance and inductance of the primary side of the coil matching the condenser. If you use a coil with very low resistance, say 1.0 ohms, it will draw a lot more current than a coil with say 2.0 ohms, and the points will probably not be happy. It's simple electronics, not mystic voodoo.

Saying that you are sorry is just another lie. Its very obvious what you are trying to do . What makes you think that you know what compression ratio that I am running . I'm running several performance modifications and as I have said many times , they all work together. You are just grasping at straws for reasons that don't apply in my case . I said that the flame thrower coil has done no harm to my original style points in 12 years when I installed my 40.000 volt coil. Your type of crap isn't helping anybody !!!

[California Travieso]

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Originally Posted by Corley

Purdy, you know it all, so there is no point in even responding. Good luck...

Corley,

I beg to differ. Based on the attitude you displayed in this thread an others it’s YOU who is the “know it it all.”

David Serrano

[Purdy Swoft]

Originally Posted by Corley

Purdy, you know it all, so there is no point in even responding. Good luck...

There really is no need in responding to your type of crap . I've owned and worked on model A's since 1960. I built my collection of model A's out of rough cars that most would shy away from . I have worked on and rebuilt every part of the model A by myself . The only help that I ever needed was for some of the machine work that I didn't have the equipment to perform . I didn't say that I know it all . I sure as hell know way more than you and your trouble making buddies from the other side and I make NO apology for it !!!!!!!

[Purdy Swoft]

Originally Posted by California Travieso

Corley,

I beg to differ. Based on the attitude you displayed in this thread an others it’s YOU who is the “know it it all.”

David Serrano

Thanks David , its good to see that I'm not alone in this thought . Thanks again . When I gets to the point that corley and his buddies are all that post here , Well , I think that you know what I mean . A lot of the people with a lifetime experience with the model A have already left . I have posted on this site for nearly 18 years . If a person goes to the profile of any of these people and read all of their posts it is evident that very little or any of their posts gave any usefull model A info .

[Purdy Swoft]

Originally Posted by Mike V. Florida

The voltage and current at the points is the same no matter what coil or points you use if the resistance of the coil is about 1.5 ohms for 6 volt and about 3 for 12 volt. The 20 or 40.000 volts do not go through the points.

Thanks Mike for pointing out this fact .

[Corley]

Well, since I owned and rebuilt my first model A in 1955, and have been wrenching on them ever since, I got you there. Also, ignition coils are not unique to model As, in fact nothing about ignition systems on model As is truly unique. And, yes, as an electrical engineer by training in college, I must admitt that I probably do know more about ignition systems than the average guy. Also, having built and worked on several high performance race engines, I have a pretty good knowledge of when an ignition system might be insufficient, and can use a bit more juice. I stand by my statement, the stock ignition system, in good condition, provides all the voltage that low compression engine can use. Any more than about 20k volts on an A buys you a big fat zero in performance.

More importantly, why is it that whenever you are called out as being inaccurate, you feel the need to belittle the person pointing out your error? Come on man, be an adult! Accept that once in a while, you may not be the expert. And please, Don't personally attack people (not just me, others as well,) when you don't know squat about them or their qualifications. It's not cool!

[Mike V. Florida]

Really? We are getting riled up over the voltage of a coil? Isn't the weather nice where you guys are? This kind of talk is usually found in the dead of winter and caused by cabin fever, not in August.


Look, for all those that are reading this, use what ever makes you feel good and gets you out on the road. Twenty thousand, 40 thousand, 100 thousand does it really make a difference in the vast, vast majority of the low compression/low HP of the A engines out there?


The single case that I can see for a 40k coil that would make a real difference is if you have blowby and your plugs get oily. I would thing (and it is my opinion and not based on any scientific study) that a hotter spark would cut through the oil better.


Fords first engine the "kitchen sink" engine ran on household voltage.