Unexplained Very Rough Running

[Nut17]

I fitted a Pertronix Electronic ignition to the Ford 1600 Crossflow engine fitted to a Caterham 7 I owned about 15 years ago. To remove the distributor cap, I needed to remove the inlet manifold complete with twin DCOE Weber Carbs. It did resolve considerable frustration at the time.

[myoldjalopy]

Likewise sorry to hear of your health issues. I think it better to get to the bottom of why the car is not running first before getting electronic ignition fitted. It has to be something simple. Once you have identified the problem then you could consider electronic ignition to eliminate the usual servicing of the dizzy, but simply fitting one now may create more issues. Plenty on here have fitted electronic to find a bit of faffing with the timing is required so its best the car is running properly first. At present we are not sure what the current issue is.

[svenedin]

Likewise sorry to hear of your health issues. I think it better to get to the bottom of why the car is not running first before getting electronic ignition fitted. It has to be something simple. Once you have identified the problem then you could consider electronic ignition to eliminate the usual servicing of the dizzy, but simply fitting one now may create more issues. Plenty on here have fitted electronic to find a bit of faffing with the timing is required so its best the car is running properly first. At present we are not sure what the current issue is.

Completely agree.

[Nut17]

Well I can now report a very positive outcome. By a process of elimination, the problem was entirely related to an almost brand new condenser. I always considered the condensers main function was to eliminate arcing at the points, and badly performing points forming a crater/peak was usually down to a dodgy condenser. Well that theory obviously is only a part of the issue as my experience has just proven. I am now happily relieved.

[ManyMinors]

Excellent news! I've had the odd condenser fail over the years. Just because something is new it unfortunately doesn't mean it'll be any good.
You do have to be careful where you source parts

[myoldjalopy]

Indeed good news - we did think it would be something simple........and an easy fix in the end - we like them!

[svenedin]

Marvellous! If you do a search you can find pictures of these rubbish condensers being opened up. They really are complete junk. You will be happy with a Distributor Doctor condenser I'm sure.

Happy Motoring!

Stephen

[Bill_qaz]

Glad you found the issue and a cheap fix

[geoberni]

I always considered the condensers main function was to eliminate arcing at the points, and badly performing points forming a crater/peak was usually down to a dodgy condenser. Well that theory obviously is only a part of the issue as my experience has just proven. I am now happily relieved.

Without getting too technical, a 'Condenser' is another name for a capacitor and is a controlled size gap for electrical energy to jump.
Old technology Condensers could dry out internally effectively making the gap far too large, 'open circuit', so will have no effect, and thus allow the back emf to burn the points.

Unfortunately the most prevalent failure of modern ones is to fail 'short circuit', thus stopping the Coil actually generating the spark....

[Bill_qaz]

So if the condenser is disconnected its no longer a short circuit and the engine will run until it can be replaced, as a get you home or as proof it is the issue.

[geoberni]

So if the condenser is disconnected its no longer a short circuit and the engine will run until it can be replaced, as a get you home or as proof it is the issue.

I think it would very quickly destroy the Points.
As I said earlier, that statement was 'without getting too technical'.


This is a pretty good explanatory video.https://youtu.be/lWyn_eV-DzM

[Bill_qaz]

It will cause arcing but for short term get you home or for diagnostics elimination, if not starting suspect, then its not an issue.
Cars have run for a while with open circuit condenser and only picked when points are bad.

[Nut17]

I am tempted to purchase a spare one to carry in the car "just in case". I am still pondering whether I should have just bitten the bullet and fitted an electronic conversion. However, I did drive about 30 absolutely delightful trouble free miles today but did notice the coil is very hot to touch. Is this normal? Or have I got another dud? I still have the shiny new NGK one as shown with the rest of the smorgasbord of components recently sourced.

[svenedin]

Not normal for the coil to get “very hot”. Coil resistance should be 3 ohms or very close. At a guess, resistance is too high. I would test the disconnected coil with a multimeter. Ensure connections are tight and that the car earth is good (“engine” earth is actually between gearbox and crossmember

Yes carrying a spare condenser is very wise.

Stephen

[MikeNash]

I hesitate to cross swords with m'Learned Friend Sven, but don't you think that Mr Nut17 has a coil that is of low resistance (hence the the high current flow that's heating it up) and it should be fitted with a ballast resistor?

For Mr Nut17, I have in front of me a Lucas "DLB102 high energy power coil 12V" that states on its label "Use with 1.3-1.8 ohm ballast resistance". In effect, its a coil that needs only 6-9 volts to work and is e3xpected to run with a resistor in series that reduces the 12 volt of your battery to this value for normal running but which is shorted out on starting. This way, an old or low battery can still provide reliable starting.

But a electrician will be along in a moment to advise us all. MikeN.
PS My coil I described above will give a 10mm spark (between spheres) on the bench with 13 volts applied, that's some 32kV in action. Only half that's needed for normal running.

[svenedin]

Well a simple test with a multimeter should determine what the coil resistance is. I am not suggesting that by design this coil is of the wrong resistance but that it is possibly faulty causing high internal resistance and hence it getting hot.

Stephen

[MikeNash]

My point is that if the resistance is high then little current will flow and so it wouldn't get hot. But I take your point that a multimeter will solve the issue.
MikeN.

[geoberni]

Well, as to the Coil.....

As

has said, Ballast Coils require a Ballast Resistor. Cars using such Coils & Resistors are wired differently to a Minor.
Such a system is essentially a 9v Coil, and that is the 'running' voltage, but when starting it gets the full 12 to it.

This is done by the Coil being 1.5 Ohms and the Resistor also 1.5 Ohms. So when the engine is running, it's a 3 Ohm Coil.
The Lucas DLB102 is a 1.5 Ohm Coil. The Minor does not require such a system so banish all such thoughts of using it on a Minor.


A 12v Coil is a nominal 3 to 3.5 Ohms.
When to Points are closed, at 12v battery power the Coil will be generating 48-41 Watts of energy.
But this is momentary On & Off as the Distributor spins around.
When the engine is running and the Voltage from the Dynamo/Alternator is around 13.5v then the Coil will be generating 56-48 Watts of energy.

This is why it's bad news to leave the Ign switched on without the engine turning; if the Points are closed that's a lot of heating energy.

Stephen, as you can see, it's a lower resistance that will cause the greater heating.

The NGK U1163 that Nut17 has in his photo is a 12v Coil, they are usually marked with "USE WITHOUT EXTERNAL RESISTOR"

I agree the Coil will be warm, even 'quite warm', however should not 'Hot'.

[svenedin]

Fair enough! I obviously didn't pay enough attention in physics at school.....

[geoberni]

Fair enough! I obviously didn't pay enough attention in physics at school.....

So many variables with Ohm's Law, people often don't realise how different resistance values in a simple circuit, like on a Minor, can affect the intended circuit, e.g. 'Bad Earths'.