Read, you may save some money !.

[RonH]

Have got a 2.3 16v.Just recently have noticed it was not starting as sweetly as it usualy does and the last time out was missing in warm up phase.Decided to check / change the basic ignition items..... plugs, rotor arm and dist. cap. Whilst changing said parts, thought i would check leads for continuety.All ok except for No.4 which had no continuety at all. Thought new leads were called for until i saw the price....50 odd £'s + !. Before i spend that sort of money had another look at the dodgy lead.Found out that the lead itself is a cut length with a threaded metal "adapter" crimped on each end.This lead is "screwed" into the fixtures at each end ...the one that goes onto the dist, cap at one end and onto the spark plug at the other, so i could unsrew the cable out of both ends and end up with 3 parts.....2 differant sockets plus the length of cable.
The crimped end that screwed into the plug end was covered in a light covering of corrrosion....much like verdigris!.
I cleaned the corrosion off and screwed the lead back into the plug connection, with a small amount of lubication, result......continuety returned!.

I don't know if it is a well known fact that a plug lead can be disassembled....i certainly never knew.....so in future will check those connections before scrapping the leads!.

I only have 4 leads... a set of 6 or 8 leads could work out VERY expensive, when all it might be is a dodgy connection!.

 

[rf065]

A worthwhile tip, but the biggest problem with high tension leads is that the insulation breaks down over time.

If you were to stick the car on a rolling road with the bonnet open & the garage lights out, you would see sparks flying all over the place.

Depending on the quality of the original leads and their age, it is sometimes worth replacing the whole lot, especially if you are experiencing misfires.

Russ

 

[television]

The spark will jump at least ½" but the snag there is that you get a timing problem,, years ago on a Hillman Imp the only way it would run on two of the cylinders was to have a spark gap to delay the spark

 

[cobra]

gap

remember that one well malc,
used to put a button in the middle of a cut lead, wire to one side of button, other half of lead to other side, just the right gap to delay spark. run for years like it (oh imp memories)
cobra

 

[television]

remember that one well malc,
used to put a button in the middle of a cut lead, wire to one side of button, other half of lead to other side, just the right gap to delay spark. run for years like it (oh imp memories)
cobra

I never thought of a button,,I used a fiber washer

 

[Xtractorfan]

My memories of using the button was to increase the spark at the plug, weak spark fit a button in the lead.........

 

[RonH]

Can see where you are coming from about old and worn leads and the capability of a spark jumping gaps.
On this particular vehicle my symptoms were (a) the vehicle, which always started instantly on the first turn of the key, started occasionaly to turn over a few seconds before firing up. (b) on my last journey, (before looking into it), could feel a very very slight missfire on accelaration for the first 30 seconds.....after that the missfire disappeared.
When i took the plug end off the lead ( where the covering of verdigris was) there was no sign of arcing or burning.......i think i caught the problem before anything more serious developed.
Talking of arcing.When i bought my 2ltr. 190e, it drove ok without any problems at all.When i did my first service i found the rotor arm had literary "rusted" onto the dist. shaft.It appeared that the dist. cap had probably not been off since the car left the factory 20 yrs. earlier !.
Not only that, the top of the rotor arm between the centre contact and the metalic segment on the side was non existant.....had been burnt away. Was amazing that the car went at all.
Not having to set points is obviously a step forward, but in this case, the distributor must have been regarded as a "non servicable item" and been overlooked when it came to servicing by the previous owner!.

 

[wireman]

Take care if you are trying to see how long the sparks could be, it needs some thing around 25 kilovolts (very weather dependent) to jump one centimetre and any more than this could damage your coils insulation and render it useless or unreliable, in addition the electronic bits may also suffer from over voltage and get killed into the bargain this damage could be very expensive to repair. The shirt button trick is as old as High tension ignition systems (100 years+) the gap helps keep the electrical time constant of the high tension circuit short and thus more energy is present in the sparking plug albeit for less time but it is a massive increase in the peak spark energy, Halfords used to sell a spark booster for tired engines which oiled up their plugs it was a bakelite cylinder in which was little more than the shirt button spark gap.

Modern resistive 10-25kohm/ft suppressor HT leads have much the same effect,these were made legally compulsary at the dawn of television and VHF radio broadcasting in the early 1950's to reduce interference but had the side effect of improving the performance of ignition systems. Modern ignition systems are intended to use resistive HT leads, don't use the so called high performance wire stuff its not good enough (and you will interfere with everybody else's car radio).