looking for a little direction. coming into a project half way through. have a 49 chevy that's been converted to 12v. stock points distributor. new stock harness. has a brand new ballast resistor on the firewall. question is ....should it have a 1.5 ohm coil or a 3.0 ohm coil with the resistor. Thanks in advance
Do you have access to an original wiring diagram? It should say what resistance is needed,, I'm pretty sure.. check it out and let me know what you find,,, curious now,,
This ought to get you headed in the right direction. http://www.jalopyjournal.com/forum/showthread.php?t=601339&highlight=gospel+bubba Anytime you see a "Bubba" thread it's usually worth a read.
"I would suggest a 1.5-1.9 ohm primary resistor and a 1.5 - 1.9 ohm primary ignition coil for proper point life ." from Bubba
Why do you say there is no difference between between 6 and 12 volt coils. They are not interchangable are they? I think i am starting to think I am lost on coils! Love to hear what you have to say. Mike
plymouth1951, some 12 volt coils have a resistor built into them, so are not useable in 6-volt systems. However, in what I think are the majority of coils, they are somewhere between 1.5 and 2 ohms. In a 6-volt system, this gets you pretty close to the maximum current at which the points will live a long, happy life. The same coil can be used in a 12-volt system, but if you use it without a ballast resistor, you are now asking the points to basically switch double the current, which results in very short point life. The addition of a resistor to lower the current through the points resolves that predicament. So in most cases, 6 and 12 volt coils are interchangeable, as long as you use the proper ballast when using them on a 12-volt system. Clear as mud, right? So to further muddy the water, electronic ignition systems can limit the amount of current that is run through the coil, so they can use coils with a lot lower primary resistance.
For standard ignitions there are basically two types of coils, unresisted, and internally resisted. Most 12 V systems run power either through a balast resistor or a resister wire from the ign switch provide 6 to 8 volts to the coil. Internally resisted coils are fed 12 V and work at the 6 to 8 volt level after the voltage drop inside the coil. So for regualar coils yes for all intents and purposes a coil is a coil. if you convert to 12v, a resistor should be used between the ign switch and the coil. If the coil is labled as internally resisted it can be wired direct for 12v operation but will not work in a 6V application as the net working voltage will be about half of the voltage supplied. This voltage drop still provides 20K volts for the spark plugs, but reduced the voltage handled by the points. In Hall Effect induction ign systems, the points are replaced by a magnetic sensor, so the points arching issue goes away and the system can run on 12v. Some systems like pertronix work on an optical trigger system and can also operate on 12V without inline resistance between the ign and the coil. In either case the coil can work hotter because of the higher voltage p***ig through, Other High Energy Ignitions like the ones with the red and yellow components are matched from their manufacturers to run according to what ever they specify.
Hi ebbspeed and plym46, thank you for the writeup on the coils and use of ballast resistors. I have heard partial explanations before but none so clear. How can we use this info to provide the hottest spark in a 6 volt application? 12 volt application? My practical question relates to my 1951 Plymouth "hot rod". I would ***ume that fuel is not being completely burned in this flathead configuration due to the inherit limitations in the flathead design. Ignition ABCs......love this stuff. A FEW CLARIFICATIONS AND QUESTIONS ON THIS BASIC CONCEPT FOR THIS AND OTHER BEGINNERS FOLLOW: .....So wouldn't a hotter or longer or multiple spark improve fuel efficiency and power.....so basic huh....I always thought a 12 volt system was a better hot rod set up due to higher voltage ...HOWEVER, since a 12 volt coil is being fed seemingly similar voltage after the resistor in 12 volt system as a coil in a 6 volt system it would seem that there really isn't an advantage using a 12 volt system on this basis alone.? TRUE? Thinking further, in a budget drag race setting with a 12 volt system, does one get hotter spark, better efficiency and more power if you run a straight 12 volts through the coil without a resistor that should be there. (yes this is hard on points for 1/4 mile) ? Just curious. Thinking further, in a budget drag race setting, would there be a benefit to replacing my 6 volt battery with an 8 volt battery or even a 12 volt battery for just the 1/4 mile race. Then switch back the 6 volt battery for the drive home from the drags! (fyi....my 51 Plymouth flathead is our once or twice a year run what ya bring drag car.......don't laugh my family has a great time.....plus we are looking for edges against other Inline 6s! Though this thread is just for understanding the basics of vintage ignition systems. Guys whether you have the patience to answer my unconventional questions or not, thanks for the info you have already provided. I like others are going to have to read and participate in forums like this to get our arms around this stuff. Thx Mike
Just a little clarification here PerTronix Ignitors are NOT Optical - they are Hall Effect! Don from PerTronix.
Why does the dictionary have 5 definitions of redundant? Or as Jake said on Two and a half men - Redumbnant
Sorry guys, got my idioms mixed regarding the Pertronix unit, and speaking of which why do most people think HEI stands for High energy ignition??? I am a bit skeptical about the use of "HOTTER" spark. If the air fuel mixture is correct length of spark delivered at the proper time, is more important the how bright it is. Once you get the flame started, the flame front pretty much takes care of itself in medium compression naturally aspirated engines. For high compression, forced induction situations, running a leaner mi**ture, a hotter spark is probably more of a concern. for drag racing an engine with less than 9 to 1 compression ratio, I kinda think trying to find the hottest coil is chasing yer tail, ***uming they are in good condtion. I have found that my warmed up 230 Plymouth engine like 4 to 5 degrees of advance over the factory setting of TDC at 500 rpm idle. My machinist calculated my CR at 8.25 to 1 with my set up. I use the vacuum gauge method to set the timing, then adjust (retard) for any pinging under load. Checked with the light it sets at 5 BTDC. I am still running the 6V coil that to my knowledge was on the car when it left the factory in 46. As a point of reference I have a buddy who ran his business coupe with a dual carbed, dual exhausted, compression enhanced engine, stock ignition, to a couple runs in the 19 second neighborhood, and the Mopar Nationals a few year back.
Quote "why do most people think HEI stands for High energy ignition???" You mean it doesnt ?? What does it mean to you??
Hall effect induction as in HEI. I believe it was in common usage to describe a non mechanical way to trigger a coil, prior to GM co opting the acronym for their coil on cap magnetically trigered ignition system introduced in 71. So is it tissue or Kleenex??? A term describing an process or a marketing name for a system? Chicken or the egg.
This and any other forum needs to be somewhat correct!!!. Its NOT the chicken or the egg at all!!!! . HEI stands for ( and always has) been the short term for "High Energy Ignition" the system was designed to jump the larger gaps of .040-.045 using a magnetic pulse control module with a varying dwell cycle. The early systems advertized 45,000 volts available to the plugs ( if needed). This later haunted GM as no one kept their cars tuned up and often allowed the vehicle to need this larger voltage, burning everything in the ignition system up at the same time. GM, Ford ( duraspark) and Chrysler all used the magnetic pulse signal generators for many years and it is still being used in other forms today. Now hall effect is another story . The Hall systems ( Ford TFI) used the interupted trigger ( on off window etc) to turn a schmitt trigger on and off . The advantage the hall effect systems had was they were very good at slow rpm or engine speed. The magnetic pulse triggers had lower signal strength at low rpm and higher signal pulse with rpm main them the choice for high rpm units (nascar etc)... To trouble shoot and work on these systems a good basic understanding is very much required.
I'll be danged, Seriously? No ****? I have never heard the term HEI referred to as Hall Effect Induction,, thanks for cluing me in..
GMC Bubba, your handle illustrates your bias. This is an automotive board, but to be Somewhat correct, we can not limit our view to automotive applications. So as previously noted Hei as in Hall Effect Induction had been around longer than HEI high energy ignition. Micheal Faraday postulated it existance in 1831, and became the basis for moving a conductor through a mangetic field. When it was realized it could work with a rotating conductor, it became the b***is for the generation of electrical energy, and as developed in smaller applications, the automotive starter and generator. As well as solinoids I believe these were in use long before High Energy Ignition. Might also help in stuff like amp meters, welding, magnetos and other kinda old stuff. Do we want to talk about Eddy Current induction also?
MAN DO YOU HAVE THIS THREAD JUST ABOUT AS SCREWED UP AS IT COULD EVER BE!!!! My so called bias is because i own a GMC powered Model A Ford, and built a GMC powered HAMB dragster not because i am a die hard GM guy!!! Now step into my arena my friend i also own a fuel injection company and have been a automotive technical trainer for the better part of 30 plus years. Jump on over to the Ford barn and check out our Ignition web site at Bubbas Hot Rod Shop.com and you will see we have been servicing ignition systems for many years and still do today!!! Also check my posts as i have been helping HAMB dudes for many years and will continue to do so. Your post was not only incorrect in regards to the discussion , it was so bad i responded !! ( i usually dont even bother with these issues). You need to get your fact corrects , maybe even buy a copy of my book on Amazon .com Automotive Fuel and Emissions Control Systems isbn # 978-0-13-505481-9 or send me a pm and i will send ya one !!!!!! You need help.........
I will check in with my priest, perhaps you should call your opthomologist as you view is myopic. As for pumping you book sales thanks but no thanks. Most of my teachers taught me a lot of stuff with books to back it up that was just plain incorrect, starting with Columbus.......... So are you denying the existance of Hall effect induction?
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