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| Making sense of the Pertronix instructions https://slantsix.org/forum/viewtopic.php?t=47613 |
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| Author: | Sam Powell [ Tue Jan 17, 2012 5:56 pm ] |
| Post subject: | Making sense of the Pertronix instructions |
This is about the Pertronix Second STrike ignition. I went to their web site and looked up the instructions for it, and they make no sense to me. http://www.pertronix.com/support/manual ... ike%20.pdf Especially the non-HEI instructions. I see no way the box is fired from either a set of points, or a VR pickup, or from another ignition module. And yet further down in the instructions they say that this box must get its input from another ignition trigger. Please look at it and see if you can figure it out. I left two messages on their tech line, and did not hear back from them. By contrast, when I called MSD tech, a live tech guy was right there on the phone to answer my questions. Sam |
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| Author: | 805moparkid [ Tue Jan 17, 2012 6:04 pm ] |
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wow ok i read them and get it... you know how there points conversion kit works? it just hooks up to positive and negitive of the coil... ok... this is the same... basically all this does is piggy back off your coil and triggers another spark at a certain time after the "original" spark... unlike an MSD box which controls the coil with its own power leads and runs off the pickup just my understanding... |
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| Author: | Sam Powell [ Tue Jan 17, 2012 6:52 pm ] |
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If you are right, that clears up a lot. So you leave the stock coil connections in place? If that is right, that does not jump out at you. I will read them again. It makes perfect sense now that you can set the crank angle after the first spark. HMM. Any thoughts on the effectiveness of this? Anyone out there running one? Would it make the first spark any different at all? Can it make the first one stronger? Maybe you must run their high energy coil too to get full benefit. Sam |
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| Author: | 805moparkid [ Tue Jan 17, 2012 8:12 pm ] |
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[quote="Sam Powell"]If you are right, that clears up a lot. So you leave the stock coil connections in place? If that is right, that does not jump out at you. I will read them again. It makes perfect sense now that you can set the crank angle after the first spark. HMM. you know what i would do... sounds crazy i know but call MSD and ask what there 6AL box dose that it wont... and why is it better... i bet they will tell you all the things it can do lol Any thoughts on the effectiveness of this? Anyone out there running one? Would it make the first spark any different at all? Can it make the first one stronger? Maybe you must run their high energy coil too to get full benefit. when i look for a better ign i want more energy... not more pulses... voltage and amps make the bang... |
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| Author: | emsvitil [ Tue Jan 17, 2012 10:20 pm ] |
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MSD is a multispark CD ignition. There's no multisparking past 3000 rpm (4000 rpm on a 6 cylinder with 6A) CD ignitions have very short sparks (time of spark) The short spark of a CD ignition is more likely to misfire than an inductive ignition. (multisparking solves that problem) Sounds like you get your normal inductive spark (spark duration of inductive ignitions are longer and less likely to have a misfire) followed by another spark from pertronix. 2nd spark is CD. Other than the unlikely event of a misfire, I'm not sure what benefit the 2nd spark has. |
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| Author: | Sam Powell [ Wed Jan 18, 2012 4:35 am ] |
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Thanks for your insight there Ed. The way MSD explains it, there is a certain percentage of ignition events that are misfires, and the second spark takes care of that . I do not know how they know that, but have read this claim in their literature in the past. Would you care to explain the difference between inductive spark, and that produced by a CD ignition? I think I understand the conventional coil operation. The windings on the primary are charged for a period of time, (dwell?) and then the windings are grounded, the charge collapses, and this sends a high voltage charge through the secondary or core wire. Right? Wrong? Something I have always wonder is how the various ohm ratings effect this? Why does this effect the need for a ballast resister? Something must be in danger of burning out without it. Is this with the low ohm variety? What is the break point between ohm ratings that need a ballast resister and those that do not? I have always assumed that the ballast resister was employed to create a hotter spark during start up, and then backing the power off in run mode. Something happens when the ballast resiter heats up, which has the effect of producing more power when needed. But I do not remember the details on that. Also, all old cars had a 6 volt ignition system. I also assumed that the ballast resister allowed them to simply keep the same ignition parts when they switched over. Was Mopar the last to drop the ballast resister? And, most important, why was it eventually done away with? Did we lose anything there except another part to fail? Thanks for moving this thread. I debated putting it here in the first place. Sam |
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| Author: | KBB_of_TMC [ Wed Jan 18, 2012 10:58 am ] |
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There's a "Performance Ignition Systems" book by Jacobs about automotive ignition systems with lots of useful info, but it wasn't nearly as thourough as I expected. The virtues and drawbacks of various designs of ignition systems has been long and hotly debated. I think it's fair to say all represent some compromise between RPM response, HV output, duration, heat, cost, etc. Basically, in the point-type Mopar systems, an extermal ballast offered several advantages. During cranking, the ballast is bypassed to allow a much greater spark energy, during operation, it prevented burning out the points and overheating the coil. The Mopar ballasts of that time were designed to heat up and increase resistance at low RPM, and to cool off and decrease resistance at high RPM. Their resistance would range from 0.5 ohm @ 0A and increase by about 0.63 ohm/A; I've measured one and it matches those specs pretty well. It was a clever idea, but having a red hot wire to do that meant that corrosion could cause it to inconveniently fail. When Mopar went to electronic ignition, not much changed except to replace the points with a transistor and the ballast became a constant 1 ohm resistor. I suspect the latter change was made for increased reliability, and having dealt with years for points, I much prefer almost any electronic ignitions. Ford & Chrysler went for a longer, lower voltage spark than a shorter, higher voltage spark as GM did. The 80's computer controlled 4-cyl Mopars moved ballast inside the computer/ignition case, where you couldn't see it unless you opened the case. I don't know what Mopars use today. Modern systems can be far csmarter than the origional generation designed back around 1970. Multispark systems can combine the high voltage of a CD with the advantages of a single long spark. My old MSD5 was not capacitive discharge and its multisparking cut out by around 1500 RPM; still, it was a huge improvement over the points. The MSD6 has had a incredibly long production run - few electronic devices have lasted so long. I've read read a paper where they used a very high power laser for ignition, but it's rather a lot of work. Long ago people also tried radioactive polonium in the plugs to help create ionization, but that has some drawbacks. Jacobs' trick was a variable reluctance system that changed the inductance of the coil as a function of average current, somewhat analogous to the old Chrysler ballast resistor trick. Whatever system you use, you might be wise to have a fallback plan in the trunk. Good Luck! |
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| Author: | Sam Powell [ Wed Jan 18, 2012 11:54 am ] |
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Thanks. I appreciate the info and time you took writing it. One question still is that of resistance of the coil. They run anywhere from .335ohms, for the Blaster II, to 3 ohms for one version of the Flame Thrower. Will using the wrong coil burn out an ignition module, and how do you chose one that is appropriate. The Blaster II is listed as OK for the HEI ignition, but when you check MSD's own replacement for the stock EHI coil, it is listed at around 4.5 ohms. How can they both be OK? What is lost and gained with each. Does the resistance of the coil have an impact on the durability of the ignition module? From what I have read so far, it seems as if the Pertronix Flamer Throw HV which is listed at 60,000v, combined with their second strike gives you the best of both worlds. This would be high voltage and longer duration with the second strike capability. Pertronix did try to call me back last night, and I was not around to take the call. I left another message. Their wiring diagram is for an internal module and you cannot tell how this translates to the external 8 pin HEI which I have. Sam Sam |
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| Author: | emsvitil [ Wed Jan 18, 2012 2:36 pm ] |
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http://www.gill.co.uk/products/digital_ ... ve_ign.asp |
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| Author: | Sam Powell [ Wed Jan 18, 2012 3:10 pm ] |
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Thanks Ed. You are always a man of maximum information with minimum words. Now the big question: Is the GM HEI ignition an inductive ignition? Sounds basic I know. Sam |
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| Author: | xjarhead [ Wed Jan 18, 2012 3:52 pm ] |
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Do a google search for "HEI Coil Info". the result is on the corvette c4 forums. For some reason couldnt get a link to work. Dave |
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| Author: | 805moparkid [ Wed Jan 18, 2012 4:59 pm ] |
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Quote: Thanks Ed. You are always a man of maximum information with minimum words.
haha... i do what i can...
Now the big question: Is the GM HEI ignition an inductive ignition? Sounds basic I know. Sam |
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| Author: | emsvitil [ Wed Jan 18, 2012 5:13 pm ] |
| Post subject: | |
Quote:
Now the big question: Is the GM HEI ignition an inductive ignition? Sounds basic I know.
Sam Yes With variable dwell |
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| Author: | Sam Powell [ Wed Jan 18, 2012 5:54 pm ] |
| Post subject: | |
Thanks Ed. I've read and re- read the information John De Armond, Dave Williams, and John Lusky provide on their newsletter which is linked on the Corvette forum. http://yarchive.net/car/ignition.html It is old stuff, maybe around '92, but it is good basic information. Tons of topics are covered quite authoritatively, or so it seems. My head is ready to explode. I will need to revisit this many times. I can see that without the multispark capability, the CDI is way too short for lean mixtures or boost applications. High voltage, but too short in duration. Here is the Corvette forum ignition discussion link. http://www.corvetteforum.net/c4/doctorj/heicoilinfo.htm SAm |
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| Author: | KBB_of_TMC [ Thu Jan 19, 2012 10:08 am ] |
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According to my notes, the stock point-type Mopar coil has a primary resistance of R=1.5ohm and an inductance L=2.4mH; the Accel canister coil R=1.1ohm and L=1.6mH; the Accel is designed for higher RPM, but sacrifices a little energy at the low end (E=L*I*I/2). A given ignition module is designed to handle only so much power; a stock Mopar module ought to tolerate I=12V/(1.5coil+1ballast)ohm~5A just fine (ignition on, car not running is the worst case for stock units). More modern units limit the dwell time (how long the coil is charging), so can tolerate higher current since it's on less time. Both my Accel chrome coils seems to work fine, but rusted very quickly, so I've been meaning to buy a black near-stock Pertronix for my Mopar. Pertronix recommends their 0.6ohm coil for their Ignitor II, 1.5ohm for their Ignitor I. If you were, say, to take a 0.3ohm coil & no ballast with a stock Mopar ignition module, the ignition on/car not running case would be 12V/0.3ohm= 36A and it would almost certainly burn out very quickly. A more modern ignition might "turn off" the current after a brief time and may have no problem with a brief high current; it really depends on the module. I would stick with manf.'s specs for each type of module. CD units send a short pulse(s) to the coil, so power usually isn't as big a problem. There is more to ignition than peak voltage - generally, if you can stick enough energy (50-100mJ) into the spark to establish a 0.1" ignition region, you ought to be fine. My old RCA Thyristor reference had a very good discussion of ignition system requirements. I even spoke with one Duster guy who ran points w/o a ballast - said the car ran great for 6 mo. until the coil "exploded". Remember, reliablity is important - you don't go anywhere without a decent ignition system. Good luck and carry spares. |
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