MSD coil

[gareth08]

Originally Posted by d clarkson

Thanks Gareth, More bloody money! I wounder if it's damaged my 6AL??

The MSD is fused internally so it shouldn't of damaged it plus being a CD ignition it's more likely to damage something else (coil) first.

You can test it by putting ignition in the On position and checking if you have 12 volts on the small red wire of the MSD. If no volts use another switched 12 volt sorce and repeat the above.
If you have no spark and the above is ok then it will need to be repaire/replaced.

[mylesdw]

The magnecor site makes very good reading with regard to HT leads, particularly their article "The truth about ignition leads"

http://www.magnecor.com/magnecor1/main.htm

[Clarkson]

Originally Posted by mylesdw

The magnecor site makes very good reading with regard to HT leads, particularly their article "The truth about ignition leads"

http://www.magnecor.com/magnecor1/main.htm

Interesting read.

[wilf]

Interesting reading Myles, and I should like to provoke a discussion:

Much is made of "skin effect" in magnecor's write up. I know skin effect exists, but it is a few years since I last worked the equations around it. I recall that it really only started to take effect at frequencies above, say, 50khz. Certainly at RF frequencies it has a major effect.

Coming back to our engine ignition systems - at 6000 rpm, we are getting only 50 Hz of spark frequency to any single plug.

Yes - 50 per second, not 50,000. So skin effect would be negligible. Unless...


If the MSD output were square wave (or close to it), then a fourier analysis would show that square wave made up of many harmonics of a 50hz base sine wave. Would they potentially be of a high enough frequency for skin efect to become significant? Discuss...........

Clue - at the 1000th harmonic, the amount of energy would be 1000th of the original. (if I remember my fourier stuff right)

[Clarkson]

Wilf, that has gone straight over my head!

[JonnyT]

Somebody always told me that I should have stayed awake for two years somewhere around the 14-16 years old point! I similarly have no idea what that is about - but it sounds good if nothing else wilf!

[gareth08]

Originally Posted by wilf leek

Interesting reading Myles, and I should like to provoke a discussion:

Much is made of "skin effect" in magnecor's write up. I know skin effect exists, but it is a few years since I last worked the equations around it. I recall that it really only started to take effect at frequencies above, say, 50khz. Certainly at RF frequencies it has a major effect.

Coming back to our engine ignition systems - at 6000 rpm, we are getting only 50 Hz of spark frequency to any single plug.

Yes - 50 per second, not 50,000. So skin effect would be negligible. Unless...


If the MSD output were square wave (or close to it), then a fourier analysis would show that square wave made up of many harmonics of a 50hz base sine wave. Would they potentially be of a high enough frequency for skin efect to become significant? Discuss...........

Clue - at the 1000th harmonic, the amount of energy would be 1000th of the original. (if I remember my fourier stuff right)

Wilf,
Like you it's a long time since I was involved at this level but.......

I'm not totally sure what the output wave is on the MSD but if it were a square wave based on 5oHz sine wave I would of thought that with the close proximity of all the other electrical items and there associated EMF signatures that even if it was of a high enough frequency for skin effect it would be insignificant compared to those so as to have no real effect.

[mylesdw]

Wilf: I believe you are right when you suggest that the output is not a sine wave but a crude square wave and as such it has some high frequency components. That's the end of my knowledge but I will put the question to our resident analogue electronics specialist at work and ask for his comment. It should be in his territory since he designs high frequency high voltage power supplied for us.

[neil still building it]

hi guys my two penneth:
http://go.mrgasket.com/pdf/sparkplug...scriptions.pdf
http://go.mrgasket.com/pdf/sparkplugs/Customfit_App.pdf
my wires:

http://www.jacobselectronics.com/Pro...eramic%20wires
good luck
neil
ps be VER|Y carefull checking the output of an MSD ''REMEMBER THE VOLTAGES !!!! it NOT 12v anymore!!!!

[PeteV]

Guys - I would be *extremely* surprised if the culprit turns out to be the wrong type of HT leads. Failure after such a short amount of time points to something more fundamental eg. faulty coil (shorted turns) or wrong voltages/ballasting etc.

BTW, the only real reason that lead manufacturers play on the 'Skin effect' is simply to try and hype up their own products!!

Pete.