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Coils,
There are differing types of coils out there, some more powerful than others, some with resistors, and some without. I think i'm missing the point/and/or confusing myself. What is the purpose of a more powerful coil if you have to just use a more "powerful" resistor along with it?
(currently running a bosch blue, with some 7.5mm wires, and platinum plugs. I will be upgrading this summer to Pertronix probably, and am wondering if there is any reason for me to upgrade to a red bosch, i think that's what they are, or getting a pertronix coil or something like it...)
--
Kyle - attending Ore. State, while my lil 68 142 (74 b20, broken m40) sleeps... (check out my cardomain site,kneedsacar
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Don't spend a cent on a coil, the original one is plenty for a NA B20.
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posted by
someone claiming to be Niel
on
Thu Apr 29 22:44 CST 2004 [ RELATED]
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Ditto. The normal setup is fine. Transistor assistance will save the points and have it run more consistent (points will not wear down, just the cam/lobe follower). Capacitive discharge (CD), if you can find it for not too rediculous a price, will improve performance, smooth out idling, and make you a generally happy person... Even make tea. My father had a friend build him a CD ignition for his Volvo that I'm driving now (it was when I was still a baby) and he always tells me how it improved performance. Unfortunately it failed after about 6 years and his friend did not get time to fix it, but this is the one electronic thing he really insisted I build sometime, so it must be worth it. I've built a kit I found at an electronics shop, but am not satisfied with the design. So next is to design one from scratch. Will let you guys know when it is done and what difference it makes.
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posted by
someone claiming to be Joaquin Novara
on
Tue Apr 27 05:54 CST 2004 [ RELATED]
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Hi. Due a short circuit on my original coil, I going trought some experiments on my amazon.
I post on bboard, and some members suggest use a blue bosch coil - a red one would be too much for a set of points. Agree.
First, I put a blue coil with 7 mm standard wires. Run a lot best than the shorted original coil, but remain some rough at idle and a bit of misfire at 5000 or more rpm (B18A engine, one ZS175 carb, C camshaft, overhauled).
Also, due some bobble on my dizzie, I adapt a electronic ignition into it (original a taiwaneese accufire, after a US compufire unit, both available for 009 distrib on VW stores, simple devices, no need additional changes, advance rely on the gadgtes of the distributor; I believe Pertronix is a evolutionated version of that simple low cost devices). After my first unit was fried due a short (my mistake) I have a replacement on my toolbox.
Due I have a brazilian red coil (and the ignition don't use points now), as a next step I change the coil and add a 0.8 omhs resistor (as the red coil instructions state). No more misfire at high rpm, but rough idle remain aboard.
After reading about procedures for reduce emission (to pass local tests, my crux), I open the sparks from 0.028-0.032 to 0.032-0.038, voila!, the idle are firm and "round" (after read on some ignition handbooks, the double voltage of the red coil help to jump on more spaced spark points).
Also, as a measure to reduce the electrical lost (the wires bright at midnight), I change the wires to old style solid copper. Also, I close the rubber covers of the wires (at the side contacting the wire) con gasket sealer.
No more midnight lights on the car, but now I ear the "fried-eggs-sound-band" on my radio. After read a article on Popular Mechanics, I return to carbon wire for the wire from the coil to the distributor - the wires from distributor to sparks remain on solid copper. Radio sound acceptable now (good FM, regular AM, I ear usually only news on the car).
This is only a single case, I'm not sure would be possible replicated it on other one. At last, it work for me.
Happy volving
Joaquin
Rojo 121 Amazon
Lima - Peru
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That's a nice story, sounds like you found something that worked well for you. I too have experimented with larger spark plug gaps, and had good results. My current setup is fine, and i don't seem to have any misfiring,(assuming it would be something obvious if it were), and it works just as well as i can expect it too. Don't have anything to compare it to, we'll see what happens when i get the pertronix this summer. I'll post my results if any.
Thanks to all for their experiences and opinions, if there are more out there, i'm game to hear them, peace,
--
Kyle - attending Ore. State, while my lil 68 142 (74 b20, broken m40) sleeps... (check out my cardomain site,kneedsacar
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posted by
someone claiming to be anthony
on
Tue Apr 27 05:50 CST 2004 [ RELATED]
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Sorry, I just had to rub this in.
I'm running my car (well, it used to run) with the bosch dizzy, but with toyota 4k-u guts. (electronics.) First I hooked up the normal ignitor, worked fine for a long while. Then I converted it to FI... and I got a toyota 3t-gte ignition box...(the whole coil pack thing.)
And since I am running my car with the 3t-gte ecu for my FI anyways, I got the advantage of dual spark...(dual below 2000 I think... after that it's single...) and knock control. (well, it'd just inject more if knock it detected. Kinda cool...)
But I can say that the ignition and fuel of the 3T-gte is seperated, the only link is the knock control...
Don't ask me why I did all this... I just got most of the stuff for free and felt like trying out.
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posted by
someone claiming to be Niel
on
Mon Apr 26 22:37 CST 2004 [ RELATED]
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The resistor is to protect the coil when the arc at the plug occurs. An arc is basically a short circuit, so the more powerful the coil the more power the resistor has to be able to handle. Actually the power rating of the coil has more to do with the core material than the windings. The more core material, or rather better quality core material, the more energy gets stored in the core and thus transfered to the secondary when the contact breaker opens.
With CD (capacitive discharge) electronic ignition, the coil is actually used differently than with contact breaker or transistor assisted ignition. With CD, the coil is a step-up transformer rather than a storage of energy, and the different types of coils does not really make that much difference. I can't tell you where to get a CD ignition, but I do know how to make one (sorry, no facilities at the moment to make it). They are large compared to transistor assisted ignitions, and generate somewhere between 300V and 600V that gets dumped into the coil. This high voltage is why they are not so popular (difficuilt/dangerous to build/maintain), but they actually work better than transistor assisted ignitions, and typically are designed with multiple sparks (say 5 per ignition event, 3 at high revs). Multiple sparks can usually not be done with transistor assisted ignitions, because the coil is too slow to build up a field. Capacitors on the other hand can be charged up very fast, and that is why CD is so good. In fact, they dump the energy very fast as well.
As far as I know Pertronix is transistor assisted ignition with some fancy compensation for dwell time. As far as I know it does not start build up the field until a predetermined time before the next ignition event, as opposed to other systems (and contact breaker) where the field is started to build up just after the last ignition event. But don't quote me on this, as I am not 100% sure. But in any case, I would fit a Pertronix coil with a Pertronix system. That will be the optimal combination, as they are designed for each other. Coils are not the same, and even the potting material (e.g. epoxy) affect the performance.
So, no streight answer (as always), but shared information (as always). Have fun...
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Be aware that pertronix reqires a 3 ohm coil for 4 cyl engines so even their coil won't work. It has only 1.5 ohm. This is according to their own instuction manual.
Mike M.
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The OE coils with armored cable (do 140s have these?) and the Bosch blue are both 3 ohm coils. 1.5 ohm coils originally used with points would have an external ballast resistor already on the car.
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posted by
someone claiming to be Clayton
on
Tue Apr 27 04:28 CST 2004 [ RELATED]
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All car type ingnition coils are step up transformers. How do you figure one kind is a storage device?
The resistor is on the primary circuit. The spark comes from the secondary. How does that protect anything? The spark isn't a "short" because it is going to ground just like it should.
Why can't a transistor switch produce multiple sparks? It does at 8000 RPM for a V-8, why not a few more on a four banger?
Maybe your electronics background is house wiring?
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"Maybe your electronics background is house wiring?"
LOL! Can you say TROLL!
Neil's description of how a CD ignition works is very good.
The primary & secondary windings in a coil are joint at the negative terminal on the coil, that is why you don't need to earth the coil. I don't think I agree with the resistor thing, Neil is going to have to run that by me again. :)
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posted by
someone claiming to be Niel
on
Thu Apr 29 22:33 CST 2004 [ RELATED]
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Yes, I stuffed up with the resistor being in the secondary... May I write that off as due to being ill and at work?
The resistor is in the primary to limit the maximum current through the coil. But it increases the time to build up the field. The time constant for current flow is RL (resistance x inductance). It takes "RL" seconds to reach approximately 2/3 of the maximum current (and thus maximum field strength). But having only 1.5 Ohms means that you will drive 8A of current through those fine coil winding wires... You will generate about the same heat as a 100W light bulb. Raising the resistance to 3 Ohms means you will drive only 4A through the winding which generates the same heat as a 25W light bulb. So less heat, but also double the time to build up the field. From these figues, you can see that 3 Ohm is a good compromise.
There are configurations that will actually bypass the external ballast resistor while cranking the engine to give it the extra power for starting, but I can't remember where (which cars) that is done.
The resistance (or rather impediance) of the secondary winding is what helps protect the coil from the ignition event. When the event occurs, the condenser (capacitor) conducts the current through it (remember that a capacitor conducts AC current, blocks DC current). It protects the points, but also (and more importantly) provides a low impediance path for the ignition pulse so the current does not have to try and run through the battery or arc across the contacts.
Good comment about the primary common joined to the secondary. With CD ignition you do not need this junction, proof again that the coil is used differently for kettering and for CD ignition systems. With kettering the coil is used as an inductor, and inductors have the characteristic that it will do it's best to prevent a change in current flow. When the points open and break the current flow, it increases the terminal voltage as much as it can to attempt to keep the current flowing. The equivalent "common man's" explanation for a capacitor is that a capacitor will try it's best to keep the voltage across it the same by allowing current to flow through it. That's how the capacitor provides a low impediance path for the ignition current pulse, attempting to keep the voltage across the capacitor 0V. Eventually (milliseconds later) the capacitor has charged up to 12V, but then the points close on it. Now the spark on the points is probably (not exactly sure at this moment) because the capacitor also has built-in resistance which is higher than the short circuit of the points, but now we are getting too deep into things.
OK, time to give my fingers a rest. And I still have not heared what Clayton's background in electronics is... (Not trying to put him down, there is a lot he can teach me about engines or something else that I know nothing about.) Wow, a rear thought provoker, KLR142!
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posted by
someone claiming to be Niel
on
Wed Apr 28 12:43 CST 2004 [ RELATED]
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My background is in electronics. I'm a test system design engineer for one of the largest international manufacturing companies in New Zealand. Our product line is mostly electric fence energizers, but we are also world leaders in farming scales and milk meters. A new venture is developing a brain activity monitor for premature babies. I'm also one of the top paid engineer here. I've started in electronics 18 years ago. Was never interested in house wiring.
With a traditional kettering ignition, a magnetic field is built up in the primary. When the CB opens, the energy has to go somewhere and gets transfered to the secondary. The condencer is there to provide a low impediance return path for when the spark occurs at the plug. The output voltage is a function of the circuit impediance.
With CD, the energy is stored in a storage capacitor, and the coil output voltage to stored voltage has a similar ratio as the secondary winding to primary winding ration. The coil is purely a stepup transformer. The spark occurs when the coil primary is connected to the storage capacitor (in kettering it is when the primary is DIS-connected from the supply).
Sorry, my mistake about the location of the resistor. I was at work recovering from a cold, and typed faster than I was thinking. The resistor is to protect the coil by limiting the maximum primary side current, and is also part of the reason why the magnetic field builds up slowly in the kettering ignition. With kettering you can get multiple sparks even at high revs, but the sparks are not that strong. There is little energy in the spark. With CD you can get high energy in every one of the multiple sparks, because a capacitor can charge up very fast.
As said, I do not know how Pertronix works and was guessing. Based on what you say, I still recon there is a transistor somewhere, because that type of sensor can not normally drive the required current. Even if it is only a single transistor in darlington pair configuration with no other components, but it will still classify as transistor assisted. By the way, dwell time is only relevant to kettering ignitions, because the primary side of the coil needs time to build up a magnetic field to store energy before the ignition event, when the energy is transfered to the secondary. With CD, there is no need for dwell time as the storage capacitor is continiously charged up waiting for the next event. CD works exactly the same as virtually all properly designed electric fence energizers.
A spark is a short circuit. When a spark occurs, there is virtually no electrical resistance to the flow of current, which is defined as a short circuit. The fact that it is through air (fuel mixture) instead of wire has nothing to do with the fact that it is defined as a short circuit.
So Clayton, what is your background in electronics?
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Niel,
As far as I know (and I may be wrong), the Pertronix is nothing but a reed switch and a rotor with four magnets in it. Basically a set of miniaturized points and a no-physical-contact method of opening them. No electronics involved.
No dispute with anything else you say, from where I sit.
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Actually, the Pertronix/Perlux is has no transistors -- it's not electronic at all; it just used magnetic switches to fire the coil. There's no dwell compensation of any sort.
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posted by
someone claiming to be Niel
on
Wed Apr 28 12:45 CST 2004 [ RELATED]
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See my other post. Magnetic switches are rated for very low current due to the nature and construction. What you refer to as a magnetic switch will have at least an integrated transistor as a buffer, which classifies it as transistor assisted.
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I like optically-triggered systems like the Crane or Lumenition.
8^)
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There are no mechanical contacts in the system; nothing to wear out -- essentially no moving parts other than the dizzy shaft itself. They are also extremely precise.
About five or six existences ago, I was a tech on a missle guidance system that used the same opto-isolator / chopper wheel technology. I don't miss that job a bit, but I did think the idea of it was cool.
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I have a Crane unit so old that it's actually an Alison :)
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I too have an Allison on my PV's motor. Of course, if it conked out I'd be hard pressed to coax it back to life on the side of the road using just odds and ends scrounged from the car. But so far it seems happy without the slightest bit of attention from me.
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I take a spare points-type dizzy with me on long road trips -- just in case -- but I've never had a whiff of trouble with the Crane (just barely post-Allison, in my case). I think the Lumenition is a bit better made yet, with waterproof connectors and such, but no real functional difference.
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I used a pertronix set-up until it died on me. How or why i don't know but the car ran crappy, gave a mighty backfire and would not restart after I shut it off. Everything seemed fine as far as the physical condition of the parts went, and as soon as I swapped in a set of points along side the rode, she fired right up. It gave me a good excuse to buy a Crane unit(also got the Crane coil). Never had a problem with the Crane, although I always have a spare dizzy w/ points in the trunk now, ready to drop in if needed.
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posted by
someone claiming to be Clayton
on
Tue Apr 27 05:23 CST 2004 [ RELATED]
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Other than the Volvo transistor, those two are the best for sure. I like the Crane one.
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"So, no straight answer (as always), but shared information (as always). Have fun..."
Exactly! Thanks!
Thanks, and looking forward to more!
--
Kyle - attending Ore. State, while my lil 68 142 (74 b20, broken m40) sleeps... (check out my cardomain site,kneedsacar
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Straight Answer
CRANE!
--
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what is the point/benefit of something like an MSD 6 "series" box type thing...?
Does anyone run one of these? Would i benefit from it in anyway?
--
Kyle - attending Ore. State, while my lil 68 142 (74 b20, broken m40) sleeps... (check out my cardomain site,kneedsacar
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posted by
someone claiming to be mjamgb
on
Tue Apr 27 05:50 CST 2004 [ RELATED]
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You can use whatever coil your heart desires. Different coils are set up for different primary circuit VOLTAGE which is what the resistor is affecting. When energized, your electrical system feeds power to the primary windings of your coil. That sets up a magnetic field centered around the core of the coil. The coil is grounded through the points on the distributor ("normal" system). When the points open the field "collapses" and a high energy pulse is created in the secondary winding of the coil. If all works properly and the stars are in alignment the pulse travels down the coil lead to the distributor, the rotor sends it to the appropriate plug lead and good things occur in the combusiton chamber.
The design of the various coils are varied by potting (oil vs epoxy) wire diameter and number of windings in both the primary and secondary. Also, they vary by resistance (here we are again). The main reason for lowering voltage through the primary circuit is to protect the points from frying (also lowers heat build up to a small extent but requires larger wire for the same current capacity). The condenser is utilized to "damp" the "bounce-back" of current in the primary circuit which would tend to cause spark flutter and further fry the points (lots of little arcs instead of the two big ones when the points separate and join again.
So-called "pointless" (breakerless) sytems do much the same thing except a "trigger" is incorporated somewhere other than the points. Many breakerless systems require STILL LOWER voltage to protect the often delicate 'tronics inside the boxes.
MSD is nice because it can set your redline with user installable selecotr plugs and the "6" has a soft reduction wherein it randomly fails to "fire" a cylinder to keep the revs at the desired point (not so harsh as cutting out entirely, especially in the middle of a corner!).
I happen to like the Mallory Unilite but that's just me and it takes twice as much ballast as the stock system.
Oh, Bosch makes two "red" coils. One is a stock unit for the older VW's and (I'm sure) other European cars (along with the various black ones), and the other is the high performance unit (really a very bright red, requires external ballast, i.e. resistor). The Bosch "blue," if you can find a real one, is internally ballasted and will work quite well in the Volvo. It is also considered a high performance unit.
In short, consult the instructions that come with any ignition system you get (or find instructions!) to determine how much ballasting is required.
Isn't this fun?
Mike!
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posted by
someone claiming to be cdu
on
Tue Apr 27 09:26 CST 2004 [ RELATED]
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> The Bosch "blue," if you can find a real one, is internally ballasted
> and will work quite well in the Volvo. It is also considered a high
> performance unit.
I've noticed that most mid 70s mercedes benz hulks that I see in
salvage yards, at least those that are not diesels, have blue bosch
coils. Are these the same sort of coils you are discussing above?
If so, that would mean there is a ready supply of these things for
cheap...
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Lol. So, what would you run a MSD 6 in conjunction with? Or is the MSD 6 a stand alone ignition module that also includes a rev limiter? There's a digital Rev Limiter from Pertronix that was designed to go along with the Ignitor...
--
Kyle - attending Ore. State, while my lil 68 142 (74 b20, broken m40) sleeps... (check out my cardomain site,kneedsacar
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