Ignition problem
 

Took the PV out today and it ran alright for the first 20 min's and then just died. Had to get recovery home. Fuel getting through but no spark at plug or back to HT lead. Does a coil just let go or are there warning symptoms first?

arcturus;

...sorry to hear...!

It is extremely rare to have an Ign Coil itself simply fail(!), although I suppose it could happen...loss of spark is more likely a result, caused by some silly little thing like a fatigued Points Wire falling off, or the Distributor Through-Bolt loosening and shorting to the Dist case, causing loss of Points Opening function.

See: http://www.sw-em.com/Volvo%20Ignitio...ition%20System

BTW...I'd rather perform some instant troubleshooting and repairs, on the side of the road using my Swiss army knife, and possibly sacrifice a "Sunday Shirt", than to suffer the indignity of allowing my neighbors to see a car of mine coming home on a flat-bed...but that's just me...

Good Hunting!

Problem solved, it was condenser again, not the usual warning hiccups before hand. I seem to need to change condensers more frequently than oil! I'm sick and tired of changing condensers, I think that I will change to a 123. as soon as funds allow.
Photo of points, note if possible the white rime on points edge, fortunately no pitting
In a way I have been lucky, I hadn't intended to take the PV today, a last minute decision to check out the 12V converters, as I will be going to a rally with it in the North of Portugal on 14 March. Round trip of over 1000km. So it happened at the right time. So far no problem with them.

arcturus;

...happy you got it sorted!

I've been hearing of more failed Condensers recently than ever before...and I've experienced one myself, when those things never used to fail...it was just totally unheard of! ...is the failed part an official Bosch part , or I fear some china s**t counterfeit part? I bet the later! I hate those p***s for that...those guys could f**k up a junk yard! Needless to say: Buy Bosch from a reputable source and stay away from shoddy china s**t goods for that 1000km rallye!

Happy Easter to All!

Am I correct in thinking that all condensers are pretty much all the same as far as values are concerned? other than fitting. I have taken to carrying spares with me most of the time in my tool box. I think that now i will carry a spare with the necessary small tools in the glove box from now on so that I can change one at the side of road if necessary.

You may want to try the following for carrying as a spare:

Go to an electronics components shop and buy an ordinary Mylar capacitor 0.22 μF (or thereabouts), 630 volt (or thereabouts) and fit an eye terminal to each end. (Who needs a metal can?)

Won’t cost you more than a few pennies.

Everyone keeps telling me to buy Bosch but i can't find a source. Any ideas?

arcturus; I'd try per mail order...do you have that option?

Simon; 0.22uF?...I thought someone measured one once and it measured around 1.0uF...I don't have a C meter so I cant confirm...do you?...could you measure one and post...I'll see about getting access to a C-meter and measuring one also. It would seem that C value is important because it must play correctly with the L of Primary...

Cheers

Putting bosch condenser into UK Amazon brings up plenty of choices; I'd be surprised if the Portuguese site was any different. Doesn't matter if it's not the identical one.

This is true, but the dependency is only square-root, so it's not as critical as all that.

I've never measured one, but I've always had it in my head that they were "supposed to be" 0.1uF. I've used anything between 0.1uF and 0.47uF depending on what I had in the junk box, and not noticed any difference.

The capacitor must be large enough to be able to store sufficient energy that the secondary voltage rises high enough to initiate the spark before the primary voltage rises high enough to damage the insulation of the condenser/coil/other primary side components. At the same time, if it is too large the secondary voltage never will rise high enough to initiate the spark. Between these points, the larger the capacitor the smaller the current in the coil at the time the spark is initiated, and the longer the spark duration and less intense the spark. The resonant frequency of the coil/capacitor wants to be high in relation to the spark repetition frequency to keep the spark duration short and the intensity up.

It's probably not far out to assume a 6V/1.5 ohms ballasted coil is 7.5mH inductance; from there we can derive that a 0.33uF 630V capacitor will not be taken outside its voltage rating even with the secondary disconnected, and the resonant frequency is 3.2kHz which is reasonably high compared to the 200Hz spark repetition rate (4 cylinders at 6000rpm). A value of 0.1uF needs a 1.2kV rating and gives 5.8kHz.