Ballast resistor with EI conversion
Printed From: CorrectCraftFan.com
Category: Repairs and Maintenance
Forum Name: Engine Repair
Forum Discription: Engine problems and solutions
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=30684
Printed Date: October-08-2024 at 11:21pm
Topic: Ballast resistor with EI conversion
Posted By: M3Fan
Subject: Ballast resistor with EI conversion
Date Posted: July-10-2013 at 9:09pm
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The instructions for my Ignitor II EI module say that it can handle the full 12V at all times, therefore no ballast resistor is needed, although it will still work with the ballast resistor in place. The coil I'm using ( http://www.msdignition.com/Products/Coils/Race/8222_-_High_Vibration_Blaster_Coil.aspx" rel="nofollow - MSD High Vibration Blaster ) says to USE a ballast resistor IF using a points-style distributor. Well, I have a points style distributor but no points with the EI conversion. Should I wire in the ballast resistor or bypass it? Is the purpose of the resistor to save the coil or the now-gone-points? I've been running it bypassed for several hours of runtime with no problems so far but figured it'd be a good idea to check. ------------- 2000 SN GT40 w/99 Graphics/Gel 2016 SN 200 OB 5.3L DI https://forum.fifteenoff.com |
Replies:
Posted By: Hollywood
Date Posted: July-10-2013 at 9:12pm
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You're fine. Looks like you are wired up just like SNobsessed. ------------- |
Posted By: wake_2001
Date Posted: July-11-2013 at 4:58pm
| Yeah, I think you're good w/ no resistor. I have the same setup at SNobsessed. Prestolite EI conversion w/ and the same coil you have with no resistor. Runs great. From what I understand the resistor is only needed if you have true points. |
Posted By: Hollywood
Date Posted: July-11-2013 at 5:24pm
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I think you mean resistor not coil in your last sentence. What's odd to me about these bypassing instructions is that this same coil will operate with full 12v (really like 14.x) or with a ballast resistor in place, obviously at a lower voltage. We haven't even gotten to the distributor yet... I really need to bring my DMM down to my boat. MSD coil (presumably an older version of what's above) with Prestolite EI kit AND ballast resistor. When we first bought the boat it suddenly died on the water and took it to a marina. The ballast resistor failed, obviously leading to no spark. I believe that's all they replaced. I will confirm that by looking at the receipt tonight. ------------- |
Posted By: wake_2001
Date Posted: July-11-2013 at 5:45pm
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Good call. Edited. Is your MSD coil epoxy filled? I went through 2 oil filled coils I'm assuming because of the mounting position (horizontal rather than vertical) or due to the fact that I didn't have a resistor in place. You can mount the High Vibration/Epoxy filled coil any way you'd like. From what I read the Prestolite EI kits don't require a resistor, so it would come down to whether or not the coil requires one. The instructions for the MSD High Vib. state that it only requires a resistor if you have points. I've seen quite a few knowledgeable posts from you on here, so you probably know a good bit more about this subject than I do, but I figured I'd pass along my experience with it all. I will say that the MSD coil is the best $55 I've spent on my boat. |
Posted By: Hollywood
Date Posted: July-11-2013 at 6:00pm
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My coil is red, horizontal and says Blaster _ (among other things I cannot recall) on it. That is all I know! So say you're running this 8222 coil with points, you put a resistor upstream of the coils power source. Then you ditch the points and put a Prestolite EI plate in (please no Pertronix) and also ditch the resistor. How can the coil perform the same with or without a resistor? That is what is still getting me. The difference in output must be negligable? We are only talking .8 ohm resistors typically. I'm not sure I have a strong enough electrical understanding to know what .8 ohms does to 12-14V. Perhaps it is impossible to know without knowing the current. I can't seem to figure it out. I must measure my ignition circuit, this is really bothering me. We can knock down the volts to the distributor with or without the coil, so leave that alone for now. ------------- |
Posted By: wake_2001
Date Posted: July-11-2013 at 6:16pm
Good question. That's where it goes over my head. 
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Posted By: SNobsessed
Date Posted: July-11-2013 at 10:23pm
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Kevin - From what I understand, the semiconductors in the EI will control the coil's current flow - it is not a simple ohm's law setup. That is why on some EI's you can ditch the coil. The nice feature of EI is that the coil is getting full energy across all RPMs. With points, the coil would get hot at one end of the spectrum, hence a resister was needed to keep it from getting too hot. But with the resister,the coil's magnetic field is not fully saturated at the other end (high RPM, I think). Later tonight I will try to find a link to a better explanation. Chris ('79 Nautique) could have explained this in 10 4-letter words or less  It won't hurt anything to use the resister if it is not truly needed, you just won't get as hot of spark. I think we over estimate how much ignition we need, but that is the nature of our community! ------------- “Beer is proof that God loves us and wants us to be happy.” Ben Franklin |
Posted By: lewy2001
Date Posted: July-11-2013 at 10:30pm
Wood simple http://www.wisc-online.com/Objects/ViewObject.aspx?ID=DCE3402" rel="nofollow - Voltage Divider Rule . It all depends on the resistance of coil. Sure 0.8 ohms is not much, but if the coil has a resistance of 0.8 ohms. It will only have 6V volts applied in a 12 volt series circuit. ------------- If you're going through hell, keep going http://www.correctcraftfan.com/diaries/details.asp?ID=2999" rel="nofollow - 89 Ski <a href="http://www.correctcraftfan.com/diaries/details.asp?ID=5685" ta |
Hollywood wrote:Posted By: lewy2001
Date Posted: July-11-2013 at 10:58pm
Chris if you ditch the coil you will have no Spark.  Those HEI's and DUI style dissy's have the coil in the cap.To simplify things the whole idea of points it to stop the current flow through the primary coil when they open. This then induces (collapse of magnetic field in primary coil) the high voltage into the secondary winding. Depending on the number of turns of wire in secondary winding (this is where the term coil comes from) it will produce a extremely high voltage (30-50kVolts) when comparing it to the 6-12V flowing through the primary winding. The main reason for the ballast resistor and for that matter the condensor(capacitor) in the old style points distributor was to make the points last longer. By stopping the arcing across the points contacts when initially opened. ------------- If you're going through hell, keep going http://www.correctcraftfan.com/diaries/details.asp?ID=2999" rel="nofollow - 89 Ski <a href="http://www.correctcraftfan.com/diaries/details.asp?ID=5685" ta |
Posted By: SNobsessed
Date Posted: July-12-2013 at 12:26am
Oops, meant ditch the resistor  Here is a good explanation of why EI doesn't need the ballast resistor - the 'coil on' time is constant regardless of RPM, therefore the coil doesn't get too much current at low RPMs: From this http://www.picoauto.com/tutorials/ignition-primary.html" rel="nofollow - Link One of the many compromises with contact ignition is the fact that the coils saturation time will reduce with increasing engine speed. In the illustration shown in Fig 1.2, the engine is running at approximately 1000 rpm and the points are closed for 16.3 milliseconds. This results in an induced voltage of 286.3 Volts. As the engine speed is increased to 3000 rpm the coils available time to fully ‘saturate’ will be reduced pro-rata. Illustration Fig 1.3 shows that the time available to charge the coil has now been reduced to 5.6 milliseconds. As a result, the induced voltage has been reduced to 275.4 Volts and the coils HT output reduced accordingly. primary ignition - figure 1.3 Figure 1.3 The dwell period on an engine with electronic ignition is controlled by the current limiting circuit within the amplifier or Electronic Control Module (ECM). The dwell on a variable dwell or constant energy system will be seen to expand as the engine speed increases, compensating for the shorter time period. The term ‘constant energy’ refers to the available voltage produced by the coil. This, regardless of engine speed, will remain constant as opposed to contact ignition where an increase in engine speed means the contacts are closed for a shorter time period. The coils saturation time can be seen in Fig 1.4, where the time available to saturate the coil is a constant 3.0 milliseconds regardless of the engine speed. The saturation time is considerably lower than that of a contact system due to the coils supply voltage being approximately double that of a ballasted contact system and the coils primary resistance approximately halved. This will result in a far higher current, saturating the coil with amperage that would not be possible on a contact system. Keep in mind that not all EI systems are designed with the same robust semiconductors, which is why some are more prone to failure. You get what you pay for! ------------- “Beer is proof that God loves us and wants us to be happy.” Ben Franklin |
Posted By: 65 'cuda
Date Posted: July-12-2013 at 1:05am
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This is an example of system that is generally robust: http://www.jegs.com/i/Mopar-Performance/312/P4120505/10002/-1" rel="nofollow - Mopar Electrinic Ignition This is the control box for the EI system, the distributor contains a magnetic pick up and reluctor for the trigger, and the box contains the circuits to manage dwell, the BIG silver transistor in the middle of the blue heat sink is the switch, rated at above 30 amps of current and OEM automotive duty cycles. This is very old technology but more robust than any "all in one" module that fits inside the distributor. I think many of the problems associated with the EI kits have to do with the environment in the boat, 30 or 40 year old wiring harnesses, spotty grounds, those little modules don't like the fluctuating voltage and and resulting noise in the circuit and behave badly. I'm chasing a ignition issue in the Barracuda right now that will probably wind up being ground, or wiring, or ignition switch, not EI module or points or coil or ballast resistor or not. ------------- Gary http://www.correctcraftfan.com/diaries/details.asp?ID=941" rel="nofollow - 1965 Barracuda SS |