MSD coil

[Clarkson]

Originally Posted by 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.

Spoke to real steal today and my leads are ok and not solid type,but may cause interfrence thats all. They also said they have never seen a duff one either! So I can only think it's a duff coil which is burn't out, or a faulty MSD 6al as well.

There is not resister required for this set up.

[oglyoodoo]

I read the info on the Magnecor link and it smacks of the hype surrounding very expensive HiFi and home Cinema interconnect cables that the gullible seem to buy. Hands up all those who have bought them!!

I do not claim to be an expert on the MSD Ignition system but take it that it can produce multiple spark discharges the number depending on the RPM. As Wilf says 50Hz at 6000 Rpm for a V8, I suspect an MSD will not give more than two and possibly only one spark at this speed.

The Coil will be driven by some semiconductor switching device probably from some high voltage source to get the current built up in the primary of the coil as quickly as possible. When the current is switched off the magnetic field in the coil core collapses and a fair sized voltage spike is generated and fed to the plugs. This pulse will have a pretty fast rise time and contain quite a few harmonics well into the VHF region. Ordinary copper Plug leads of varying lengths will act as fairly good aerials at various VHF frequencies and propagate Interference to other equipment. Old farts like me will remember the havoc it could cause on VHF 405 line TV. Suppressor plug caps and resistive leads which, together with the distributed stray capacitance, slow down the rise time of the pulses making the aerials less efficient and in the process generating less interference. Similarly winding the ignition leads into a spiral will increase the inductance and again slow down the rise time. In this case of course the DC resistance will be lower than that of a resistive lead.

Having ignition leads with minimal skin effect and hence good high frequency performance would appear to be the opposite of what is required. In any case I don't believe for one minute that skin effect has any bearing whatsoever on the performance of an ignition system MSD or otherwise.

Denis

[mylesdw]

Oglee: I put the question to our resident 'expert' at work and his conclusion was much the same as yours and Wilf's: skin effect is not very relevant.

On a similar thread recently, one of the guys stuck a 'scope on an MSD box and you are right: it gives only 1 pulse above 3000 rpm.

[Clarkson]

Well pi**ed off now! after changing the coil and ht leads, still don't start!!! Removed my MSD 6AL box and that's fried too! Anyone got a second hand one??

That's what happeneds when you buy second hand!

[Purple AK]

Dave. What coil are you using? You said today that it wasn't a normal stock coil. I only ask because the MSD6 series are not compatable with some race type coils Which maybe your problem. http://www.msdignition.com/pdf/6%20series/6series.pdf See page 2. Apart from loosing the rev limiter, could you not wire it without the MSD for now?

[mylesdw]

Chuck it out and get a Piranha unit. Smaller, neater, 2 year guarantee and for the price of the MSD unit you can buy two and carry a spare!

[Clarkson]

Chris, I have got a msd p/n8207 like this http://www.msdignition.com/coil_blaster_6_8207.htm

I could use my old HEI for now!

[Clarkson]

Originally Posted by mylesdw

Chuck it out and get a Piranha unit. Smaller, neater, 2 year guarantee and for the price of the MSD unit you can buy two and carry a spare!

Never heard of them??

[Clarkson]

Well after a little invest I found out that the MSD6AL box has a burn't out diode, inside the msd box next to the orange wire! Anyone know how can repair them or is there any electronic geeks here that can do it??

Anyone got a second hand one for sale, please????