Cov climax problems...

What sort of mag is it? If it is one of the Vertex types, they are often interchangeable with a distributor. However, if it at least coughed then there is life in there somewhere and I wouldn't give up on it yet - after all it ran ok only a few months ago! I'd start with a good clean up of the points and check the plug leads etc (if of the screened type, they are particularly prone to breaking down with no obvious external problem).

Clean the points, Andy. A bit of fine (400 grit or finer) wet 'n dry folded in half, slipped between the points when closed and moved too and fro will do it. Lubricate with Easy start or WD40, then a bit of clean cotton with meths on it until it comes out clean.

Have you drained the carb first to get rid of the dead petrol?

Are the plugs wet?

Try putting a NEW plug in one hole and see if it fires it up.

Regards,

Kim

"Andy G" wrote (snip):-

Joe Lucas doesn't really deserve the ' Prince of darkness' soubriquet - when cost retraints were relaxed (ie on military and aircraft equipment) they were capable of producing top quality kit, however the civilian motor and motorcyle industries got exactly what they paid for!

Here is a vertex type mag:-

{5630DEF9-90B7-0FC3-4F54-40EB6A66592F}&viewby=imagesIn this instance by Scintilla, but I'm pretty sure Lucas made them as well.

I have read in the classic motorcycle press that suppressed leads, resistive plugs etc don't mix with mags, but I have yet to see an explanation of why - a spark is a spark however it is produced and I can't believe that the minimal voltage drop introduced is significant.

Gents,

I think its one of our very favorite 'prince of darkness' range. I cleaned the plugs up and made sure the gap was correct, and petrol was certainly getting to the plugs (a couple of attempts and they were wet). I seem to remember that I had hell and all trouble to start it when I first got it. I'll try again with cleaning the points (although they look ok to me, certainly my minor runs on worse!) One question that I don't think I've asked before is this: Do silicon leads work ok with mags, or do I replace with proper ignition cable? Also a very strange point here, the boots that go over the plugs have been cut back so that the connection is only just covered, any idea why? Is there anywhere were I could get a new set of points from or do I resort to the old, go down the auto-factor and borrow they catalogue for an hour?

Thanks for your help, I'll be back near the old girl on monday, so will give you a report on tuesday!

Andy G

"Arthur G" wrote (snip):-

leads allow the magneto voltage to get higher

one is present) failure.

ISTR peak voltage across a spark gap appears immediately before the spark 'strikes', by the time the current and thus I.R drop, peaks, the voltage across the gap itself should have dropped. So one would imagine that total voltage would only become excessive if the lead has started to break down in the way Peter suggests.

Whatever the reason it certainly appears that practical experience suggests carbon cored suppressed leads should be avoided, but am I right in thinking that some 'posh' aftermarket suppressed leads consist of a fine (metal) wire coiled around a cord (like the old line cord mains droppers if anybody remembers them), presumably damping any rf oscillations by virtue of being a rather lossy inductor?

Resistor leads are basically graphited string, not wire, and the hotter spark from a good magneto will quickly cause failure through burning between the graphite flakes inside the core. Movement of the wire while the engine runs causes varying resistance between the adjoining flakes, which leads to burning and eventual failure.

I don't know what is used on cars these days, but the old leads had a very bad reputation in the 1960's and 1970's, after which it became plug caps that failed through salt ingress.

Peter

-- Peter A Forbes Prepair Ltd, Luton, UK snipped-for-privacy@easynet.co.uk

All, Only copper HT leads should be used on old magnetos, the modern resistive leads allow the magneto voltage to get higher than the design voltage and can lead to coil failure and distributor (if one is present) failure. A wealthy friend of a colleague found this to his cost when his vintage Lagonda had to be towed home from Spain, despite the fact it has both magneto and coil ignition systems, each one connecting to a separate plug in each cylinder. The firm who had refurbished the magneto for him would not do any repairs under guarantee as he had used resistive leads.

If the leads are of the modern sort, I would suggest a change to copper ASAP.

Regards, Arthur G

"Nick H" wrote (snip):-

Hmmmm... NH has digit problems? :-))

Peter

-- Peter A Forbes Prepair Ltd, Luton, UK snipped-for-privacy@easynet.co.uk

"Prepair Ltd" wrote

? No understandy Peter.