Petronix Ignition


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By FORD DEARBORN - 9 Years Ago
Greetings to all: One of several items on the winter to do list is installation of a Petronix ignition system and would like to share the results of my crude experiment. I did a little comparison of the stock system on my '64 F100 versus the Pertronix Ignitor 2 and the Flame Thrower 40,000 V coil. I will try to explain why I chose those components. The Ignitor 2 is capable of handling more current than the Ignitor 1 and will shut the system down if the ignition key is accidentally left in the on position with the engine not running. That feature saved the day several time during this test. I actually put an ammeter in the primary circuit to prove this. The Flame Thrower 40KV coil is one of the "less powerful" coils with 1.5 ohms primary resistance which will not load the Ignitor 2 anywhere near it's potential. Thus allowing it to hopefully run on the cool side. Probably most important, this coil can be used with out the ballast resistor/wire. The stock factory coil feed wire coming from the "C" terminal of the ignition switch, through the resistance wire now controls a relay which switches a 12V source to the new coil. The voltage drop with the resistance wire still in the circuit feeding this relay is only a meager 250mv. so no problem there.  Wanting desperately to be able to check and adjust the 2 advance mechanisms I went on the hunt for a distributor tester and luckily found one not working in my community cheap. Long story short: Fixed it - works excellent. First test is with points/condenser dizzy in the machine, stock coil fed from a 12V source and ballast resistor duplicating the system in my '64 F100. Put a spark plug wire in the coil tower with a plug gaped to .055" at the other end. The negative/ground to the plug is through a jumper wire the end of which I held with a plastic spark plug wire tool. With the machine set to about 1000 dist. RPM's a nice blue series of sparks appear at the plug gap. Slowly moving the grounding wire away from the spark plug drew an arc which started to misfire at about 3/8" after which the voltage was insufficient to sustain the .055" gap and the 3/8" to the ground wire. Still, not bad for a stock system, I thought. Next test is with the Ignitor 2 in the dizzy and the Flame Thrower coil WITH BALLAST resistor. I found not much difference with this arrangement under the above conditions. Next test, the resistor was removed allowing the coil to breathe full 12.5V and what an extreme difference removing the resistor made. Instead of the arc quitting at 3/8" distance it now required moving the ground wire over an inch where the arc finally flamed out. The sound of this was very much louder and bright crispy blue and the garage soon began to smell of ozone. Like, Frandenstein's lab.. Looking at graphs and scopes depicting rapid rise time to saturation and all that is proof of the improvement but actually being able to see, hear and smell (but not feel) the difference was rather eye opening. Anyone contemplating the Pertronix up-grade and choosing a coil that is designed to be used with out the resistor and installing it as such will produce the best results. In my location I can't drive the truck (damn road salt) but I did time the dizzy to the engine and found I needed to lean the idle mixture screws slightly more than 1/4 turn. I'd like to give some credit for this to more complete combustion from a much hotter spark with plugs in the engine now at .044."  Now must wait for spring to attach the air/fuel meter and dial in the carb.. I'm not too good at explaining things in text so I hope this was interesting and not too confusing. thanks, JEFF.....................
By 57RancheroJim - 9 Years Ago
Thank you for posting your testing and results, I found it quite interesting. I installed a Pertronix II and coil last year for the safety reason you mentioned. I really haven't noticed any improvement as far as performance or gains in MPG that some people claim but that wasn't the purpose of installing it. I haven't opened up the plug gaps yet, just waiting until my next plug change.
By charliemccraney - 9 Years Ago
Patiently waiting for the "feel" results.
By 57RancheroJim - 9 Years Ago
Just as a little side note. I have driven all my cars with points since 1965 countless miles and never had a failure. I'm not 100% confident in electronic stuff and still carry points and condenser with me as back up. I do have an original Pertronix in my 66 Mustang since 2001 with no problem. This is the first time I have used it in a Y block.
By 57RancheroJim - 9 Years Ago
Roger, I have never found maintaining a points system a problem, just a little work but not really much and have been doing it for years. The problem I have now is the parts are all made off shore and most of the parts are crap, especially condensers dead right out of the box.  But I heard that Pertronix is being made off shore now too! I don't know if that is true or not. I've read many posts of Pertronix coil failures now, I don't know if it's the parts problem or how the person installed them?
By FORD DEARBORN - 9 Years Ago
Greetings to all: 57RancheroJim, not sure if you eliminated the resistor on not. From the above experiment, not much of an improvement was noticed with just the Pertronix Ignitor 2 and Flame Thrower coil.  The big improvement was only after eliminating the ballast resistor in the primary circuit ,which in my case, doubled the current on the primary side of the coil. That being said, one has to be sure the electrical system is up to the task. 50+ year old wiring and switches may not cut it for long. The points/condenser system is fine and very reliable. We all have our reasons for up-grading things and in my case, it's for efficiency.  Next step will be to dial in the carb this spring.  Charliemccraney? If ever in my remaining years I get another poke from a spark plug wire, guess who I will quickly remember....LOL.   Hope this helps, JEFF..............
By 57RancheroJim - 9 Years Ago
Jeff: I'm not using the ballast resistor, just straight 12V from the ignition switch, actually closer to 14V at the coil. I keep the ballast resistor, original coil, points and condenser in my back up box behind the seat. Maybe not noticing any improvement in performance is my seat of the pants dyno needs calibrating LOL.

Rodger: I'm sure a factory type upgrade would be better but I'm not going to that extreme for my street car. Finding parts out on the road would be easier but thats why I carry my backup stuff. I've been driving/building Fords since 1965 and have never been on a tow truck. I still have points in my 1960 F100 Panel 223 six and it has 340,000 miles, so just imagine how many sets of points I've changed on it. Call me crazy but I enjoy doing that kind of work.
By 2721955meteor - 9 Years Ago
I went to duraspark2,have used it for 2 years on my 57 ranchero,starts instantley even when left for weeks.widened gap on plugs, use resistor oncoil. easey to convert,several good posts,tho the 1 i used failed to show wire from start term on coil to box must be used or engine won't start till key back to run, another plus is if you wanr retarded timeing on start there is a wire to do this
By Nat Santamaria - 9 Years Ago
Hey Ford Dearborn
I would be interested in your results. I have a 57 tbird with a 312 with a Fordomatic. When I bought the car in 2006 the car came with the Ignitor 1 and stock Ford coil with external resistor. I upgraded to the Flamethrower 40,000 V oil filled coil. I noticed an improvement on performance especially when pulling away from a standing start. The car had better zip and the acceleration was crisp. The exhaust smell was also greatly reduced. However I have gone through about 4 coils since. They seem to burn out within a year to 18 months. The problem is the Flamethrowers get very hot running them without the external resistor. Running them with the external resistor, the coil runs cooler but it affects the performance. Also if you are running the coil in horizontal stock mount, it is recommended to use the epoxy filled coil other wise the oil can start to leak out. Apparently the oil will not fully cover the windings when in a horizontal position. I was thinking of upgrading to the  Ignitor II but I am not sure if there would be any performance advantage going to the Ignitor II and if it would help in preventing the coils from burning out.
By charliemccraney - 9 Years Ago
I used the ignitor 2 and matching flamethrower 2 coil and never had a problem with the coil.  I do not recall if it was oil or epoxy filled.  I also managed to fry the unit after leaving the ignition on, so the protection that the ignitor 2 has is not a guarantee against that.
This was 8 years ago, though, and that is plenty of time for Pertronix to have had a "better idea" that causes more recent coils to fail prematurely.
I did not notice any difference vs points but this was also in a fresh distributor.  I think electronics mask wear in old, worn distributors, which produce a perceived performance increase.
By 57RancheroJim - 9 Years Ago
I'm NO electronics expert but from what I have read elsewhere about the coil failures is a coil that doesn't use an external resistor/resistor wire has the resistor built in and that adds to the heating problem. If you had a true 12V coil it would have to be the size of a toaster or larger. Maybe Pertronix better idea was having them built off shore! This may be another case of vendors that don't give a damn about customers and are only concerned with how much money they can make.
By GREENBIRD56 - 9 Years Ago
(1) Coils are made of wire wraps - depending on the gage of the wire (and its alloy) it will have a resistance based on so many OHMs per foot of wire. if you want more or less OHMs - you put more or less feet of wire in there. Or you change to a wire with different OHMs per foot. I don't believe any of them actually have a "resistor" hidden inside to adjust the OHMs. It is a designed length of wire of a fixed rating - longer / shorter/ more resistance per foot - or less. .
(2) To put energy into a coil of a given number of OHMs, you feed it a Voltage and AMPs flow according to "OHMs Law" (volts equals amps times ohms) - and on our engines, you leave the circuit closed for a given interval - the DWELL. The Volts times the Amps is WATTS - and that will be HEAT energy. So if you take a low OHM coil and feed it 13.5 Volts and leave it on for 23º dwell there is going to be a temperature rise - a larger rise than if you have a higher OHM coil at the same 23º. To hop up an engine in my youth - we would put a dual point distributor on there, therefore jack up the total dwell and get a "hotter" ignition - with the very same coil. The Ford "Duraspark II" factory electronic controllers have exactly the same dwell as a set of well adjusted single points - but it never changes - no wearing parts.  
(3) If you are going to build a "hot" coil - the insulation rating of the wire becomes important. Older model coils were oil filled - and the oil was supposed to soak the heat away to the cover shell, where it is radiated away. Keeping the wire inside well covered - made sure there wasn't a "hot spot" where the wire insulation could break down. In the present day - the oil is gone and the modern insulation coverings are a plastic or epoxy intended to take the heat directly - no more oil. The quality (or lack there of) of modern replacement coils gets discussed here a lot!
(4) It takes a maximum of 10,000 volts to fire a spark plug in most all circumstances (usually less). Have a coil of 50,000 V rating? - It is the rating of the wire and enclosure insulation - and makes great advertising - but the plugs still fire at 10,000 volts or less.


By Pete 55Tbird - 9 Years Ago
Thanks Steve. Good explanation.
A note to those guys recommending points. Remember Henry Ford started with cars that had MAGNITOS but we don`t use those anymore either. Why not? Pete
By 57RancheroJim - 9 Years Ago
GREENBIRD56 (2/5/2016)
(1) Coils are made of wire wraps - depending on the gage of the wire (and its alloy) it will have a resistance based on so many OHMs per foot of wire. if you want more or less OHMs - you put more or less feet of wire in there. Or you change to a wire with different OHMs per foot. I don't believe any of them actually have a "resistor" hidden inside to adjust the OHMs. It is a designed length of wire of a fixed rating - longer / shorter/ more resistance per foot - or less. .
(2) To put energy into a coil of a given number of OHMs, you feed it a Voltage and AMPs flow according to "OHMs Law" (volts equals amps times ohms) - and on our engines, you leave the circuit closed for a given interval - the DWELL. The Volts times the Amps is WATTS - and that will be HEAT energy. So if you take a low OHM coil and feed it 13.5 Volts and leave it on for 23º dwell there is going to be a temperature rise - a larger rise than if you have a higher OHM coil at the same 23º. To hop up an engine in my youth - we would put a dual point distributor on there, therefore jack up the total dwell and get a "hotter" ignition - with the very same coil. The Ford "Duraspark II" factory electronic controllers have exactly the same dwell as a set of well adjusted single points - but it never changes - no wearing parts.  
(3) If you are going to build a "hot" coil - the insulation rating of the wire becomes important. Older model coils were oil filled - and the oil was supposed to soak the heat away to the cover shell, where it is radiated away. Keeping the wire inside well covered - made sure there wasn't a "hot spot" where the wire insulation could break down. In the present day - the oil is gone and the modern insulation coverings are a plastic or epoxy intended to take the heat directly - no more oil. The quality (or lack there of) of modern replacement coils gets discussed here a lot!
(4) It takes a maximum of 10,000 volts to fire a spark plug in most all circumstances (usually less). Have a coil of 50,000 V rating? - It is the rating of the wire and enclosure insulation - and makes great advertising - but the plugs still fire at 10,000 volts or less.


I should have said built in resistance, not resistor, sometimes something shorts out between my brain and the keyboard, my bad..

By FORD DEARBORN - 9 Years Ago
Greetings to all: I have thus far only been able to compare the two systems by running them on the distributor tester. I'll have to wait until spring to run the Ignitor 2 and the 40,000V coil in the real world. I chose the 40KV coil due to it's higher resistance of 1.5 ohms to hopefully not build up as much heat.  Reading the last several posts tends to throw water on this logic. Nat burned-up several 1.5 ohm coils and Charlie used the lower resistance coil and never had a problem.  This suggests the 40KV coil may not be up to the task if the resistor is eliminated making the Flame Thrower 2 coil the better choice?  As for leaving the key on and engine off, I did put an ammeter in the primary circuit and when the dist. machine stopped, the current dropped to zero with 12.5V still present.  Maybe Charliemaccraney had a defective Ignitor 2.   As stated in my first post, I was able to lean the idle mixture screws over 1/4 turn and the exhaust seemed to be more pleasant.