6 Volt CDI units?

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Mervyn Hyde
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Re: 6 Volt CDI units?

#31 Post by Mervyn Hyde »

Nice work Jack. I am going to get one as well to eliminate that pesky condenser.
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Re: 6 Volt CDI units?

#32 Post by C J Murray »

Jack Walter wrote: I've been following Fred's experiment with the ceramic capacitor as well.
Like the Brightspark?
Interesting. http://www.brightsparkmagnetos.com/easycap/index.htm

Jacques mentioned that some 4-cam engines require CCW distributor rotation. The 123 distributors can be used either CW or CCW.
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Re: 6 Volt CDI units?

#33 Post by ray nelson »

I've got an old Delta 6v CDI unit that I never installed. Are/were these any good. I bought it new but really never saw the need to use it since the stock points, etc. never seemed to be a problem.
Any thoughts?
Ray

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Alan Hall
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Re: 6 Volt CDI units?

#34 Post by Alan Hall »

Ray, Opinions will vary but I ran a 6volt Delta CD ignition for years with no problems. No point erosion and no fouled plugs with an engine that was getting tired and burned oil. Only removed it after an engine rebuild to go back to a more original look.

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Re: 6 Volt CDI units?

#35 Post by Paul Lima »

I put a Delta Mk 10 in my '68 911 when new; by the winter of 68-69 it was dead (in a blinding snowstorm). Five month lifetime didn't cut it for me.

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Re: 6 Volt CDI units?

#36 Post by Mervyn Hyde »

I have asked this question earlier, but do the Brightspark folk make a product for a stock distributor (e.g., Bosch)? I can only see magneto applications, unless I am missing something obvious.
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Re: 6 Volt CDI units?

#37 Post by Fred Winterburn »

Merv,
I saw the brightspark website and the products. Looks like they sell a 220nF which is the same as 0.22µF that is typically the standard capacitance for a Kettering condenser. What I didn't llike is the small physical size and the voltage rating. There is a lot of current the condenser needs to handle, and if there is a misfire that results in all of the energy oscillating between the coil inductance and the condenser, the current is considerably higher for a much longer time period (about 10 times longer). The condenser can get really hot and the voltage rises further causing extreme stress. The capacitor I looked at is still quite small physically as you know, but significantly larger which usually means higher wattage capability. It is also rated for 1000VDC for a wide safety margin. I suggested that particular cap for the Lucas condenser shells because it looked like it would fit. Testing shows it should also be an improvement over the standard condenser in performance too. Another company also sells a ceramic capacitor as I found out later that is probably very good too.
http://www.thorcap.com/index.htm Fred
Mervyn Hyde wrote:I have asked this question earlier, but do the Brightspark folk make a product for a stock distributor (e.g., Bosch)? I can only see magneto applications, unless I am missing something obvious.

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Re: 6 Volt CDI units?

#38 Post by Mervyn Hyde »

I potted a ceramic condenser as you suggested and it seems to work fine in testing. Careful work is needed, however, as aluminium does not always like solder. The Brightspark products on my quick look at them are for magnetos. I could not see how they would work in a Bosch distributor?
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Re: 6 Volt CDI units?

#39 Post by Fred Winterburn »

Oh, I can't solder aluminum. I have successfully soldered stainless steel, but even that is difficult. I think the condenser shells on my old Bosch dizzys were steel (Volvo) as I remember them getting rusty. I'll check tomorrow as I have an old one in my shed. I would go for a very good mechanical connection with a small bolt and washers and then do the potting to keep air and moisture away from the mechanical electrical connection. Or, even better, find a steel shell to work with so solder adheres properly. In any case, using a CDI obviates the need for the condenser unless one wants to switch back to standard Kettering. Fred
Mervyn Hyde wrote:I potted a ceramic condenser as you suggested and it seems to work fine in testing. Careful work is needed, however, as aluminium does not always like solder. The Brightspark products on my quick look at them are for magnetos. I could not see how they would work in a Bosch distributor?

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Re: 6 Volt CDI units?

#40 Post by Fred Winterburn »

I just checked the old Bosch distributor that was on my 66 Volvo 1800 (have a Mallory dual point on it now triggering a CDI) and the condenser is a Bosch brand that looks similar to the Porsche 356 condenser pics I've seen. The condenser shell is zinc plated steel. One of those would be the better bet to pot a new capacitor inside. Fred
Fred Winterburn wrote:Oh, I can't solder aluminum. I have successfully soldered stainless steel, but even that is difficult. I think the condenser shells on my old Bosch dizzys were steel (Volvo) as I remember them getting rusty. I'll check tomorrow as I have an old one in my shed. I would go for a very good mechanical connection with a small bolt and washers and then do the potting to keep air and moisture away from the mechanical electrical connection. Or, even better, find a steel shell to work with so solder adheres properly. In any case, using a CDI obviates the need for the condenser unless one wants to switch back to standard Kettering. Fred
Mervyn Hyde wrote:I potted a ceramic condenser as you suggested and it seems to work fine in testing. Careful work is needed, however, as aluminium does not always like solder. The Brightspark products on my quick look at them are for magnetos. I could not see how they would work in a Bosch distributor?

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Re: 6 Volt CDI units?

#41 Post by Mervyn Hyde »

Cheers Fred. The one I used for the 'potting' was an old Lucas can that must have been steel based as it did solder after scraping back the coating.

I still can't find a direct reference to Bosch distributors and the Brightspark product?
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Re: 6 Volt CDI units?

#42 Post by Fred Winterburn »

Merv, I couldn't find a reference either, just the capacitance values listed on their website. I don't think brightspark lists a direct replacement for the Bosch condenser. I believe the intent of their product if they do not have an exact fit, is to cut down the base plate the surface mount capacitor is soldered to, and make it fit where the old condenser was mounted, usually inside the dizzy. On the externally mounted Bosch condenser, the brightspark would look a little out of place. I like the idea of potting a tougher capacitor inside an old shell, with one lead soldered to the inside so that everything looks as close to standard as possible. I might do the same for my Mallory dizzy on my Volvo as the condensers have been failure prone for the last 20 years or so that Mallory was making parts. I already have the new condenser on the Lucas dizzy in my Morgan, but it won't be working hard with the points only triggering the CDI. However, it's nice to have a known good condenser that will take the voltage and current in case I ever need to switch back to standard ignition. Fred
Mervyn Hyde wrote:Cheers Fred. The one I used for the 'potting' was an old Lucas can that must have been steel based as it did solder after scraping back the coating.

I still can't find a direct reference to Bosch distributors and the Brightspark product?

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Re: 6 Volt CDI units?

#43 Post by Al Zim »

Evidently I have gotten a lot smarter since my post about the BMW motorcycles. It would seem to me if you have a electronic device that changes 6 volts to 12 you will have an abundance of choices in CD units for your car. At some point in time (not too distant in the future) 6 volt armatures and regulators will no longer be available. Make a plan for this. Zim's offers a 6 volt alternator for push rod cars. al zim
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Re: 6 Volt CDI units?

#44 Post by Fred Winterburn »

There are a few potential problems with that approach as opposed to using a CDI dedicated to a 6V system.
-One potential problem is current capability. Will the device provide enough amps in a near instantaneous period to provide the current requirements of the 12V CDI? Some CDIs such as the old MSD 6A required high instantaneous current for each spark, hence the heavy red wire connected directly to the battery. Any CDI without an oscillator type power supply usually charges the discharge capacitor in one half cycle and this requires high instantaneous current or the spark will be weak.
-Will the DC to DC converter mimic the operation of a battery? Most converters have a rectified output, meaning no reverse current from the positive output to the negative output is possible. A battery allows for a low impedance reverse current once the reverse polarity voltage exceeds the battery voltage. Some CD ignitions rely on this to clamp the spark polarity negative and to reduce ringing from the coil inductance from interfering with the next spark in the series. The old MSD was like this, and quite likely the newer ones too.
-What voltage range will the DC to DC converter work within? If it is only effective between 5 and 7.5 volts which would be fine for powering a 12V radio, then it won't be effective for an ignition system that should be able to produce a healthy spark below 5V.
-How clean is the DC output of the converter? If not properly filtered, it could lead to spurious triggering of the CDI as some do not have good internal filtering and rely on the battery to provide most of the filtering.
-And finally, the added DC to DC converter adds complication that may be the weak link of the ignition system. Fred
Al Zim wrote:Evidently I have gotten a lot smarter since my post about the BMW motorcycles. It would seem to me if you have a electronic device that changes 6 volts to 12 you will have an abundance of choices in CD units for your car. At some point in time (not too distant in the future) 6 volt armatures and regulators will no longer be available. Make a plan for this. Zim's offers a 6 volt alternator for push rod cars. al zim

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Re: 6 Volt CDI units?

#45 Post by Al Zim »

Perhaps I am naive in my thinking and certainly having degrees in Psychology do not qualify me as an electrical engineer but I would think that someone could easily design a power supply that would supply the proper voltage and amperage to operate a CD unit properly. On my desk I have a solid state 6 volt regulator in a Bosch black regulator box that was designed by the person that produced a lot of our electrical mechanisms he was not an EE but all his stuff worked and we are still selling it. al zim
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