Induction Coil

[Non MemberParticipant]

Hi,

My 11b 1955   starts fine when cold. However, out on the open road after a time the engine starts to judder as though misfiring.

Although this gets gradually worse the car keeps going until I come to say, a set of traffic lights and have to stop. The engine cuts out and will not restart for about an hour when it has cooled down. My chief suspicion is the induction coil. I’ve verified that the 12v d.c. is getting to the low tension side.

Anyone any ideas or comments on this?

Thank and Regards

David Murphy

 

 

[David SelfridgeParticipant]

This happen to my Traction a few years ago, I had to run an earth wire to the distributor, the car never misfired again.  I am sure you have already taken out the plugs, but if you have not it’s worth checking, as I have experienced a plug centre broken and floating around, given intermittent spark (new plug recently fitted) Check the Distributor Cap for cracks although unlikely as your car would always be misfiring. You should also check the filter from the tank outlet, located at the top of the fuel tank, inside boot it may be clogged and restricting the fuel supply.

Davy

[Non MemberParticipant]

Thanks for that Davy

I’ll go over those things and give it another try.

David

[Peter FeredayParticipant]

Hi David

I had an identical problem a couple of years ago with my 11B. Car would run ok for a few miles then stop at a junction or similar and not restart for an hour or two. I was convinced at the time that it was a fuel problem, even stripping and rebuilding the carb by the side of the road one time. I had discounted the ignition side as all was new – electronic distributor etc. Eventually I replaced the new – well 2 or 3 year old –  coil with the original 60 year old SEV one  and all was well. Still is….. Must have been the new coil breaking down inside when hot.

I note you have an 11B but it is 12 volt – does that mean you have a relatively new coil???

 

 

Peter

[Non MemberParticipant]

Thanks Peter and Davy.

As it turned out problem was due to contactor points gap.

Went through the suggestions, checked plugs, distributor to coil earth strap, fuel filters, tracking on distributor cap and condensor.

When it came to the points it turned out the gap was less than 0.2mm, could have been as low as 0.1.

Set the gap back to 0.4mm and away it went. Also improved the tickover, had to adjust it back and the car seems more lively out on the road.

David

[David SelfridgeParticipant]

Hi David

I am pleased for you, getting the problem sorted, sometimes it’s the little things that are easily overlooked and  causes the biggest problems, it’s so easy to read to much into ignition problems. You did the right thing try and eliminate one thing at a time.

Happy Summer Motering

Davy

[Martin de LittleParticipant]

When a car is difficult to start, and or misfires, and or does not seem to pull well, typically folks will  immediately start tearing their car apart. First up…. do you have  copper cored plug leads ? Yes –  then carry on checking everything. If not that may well be your problem right there.

Copper cored plug leads do not break down, they always and forever  deliver the  HT full voltage  from the coil and they are dead easy to fit. The cheap modern option is  – in essence –  a cotton/graphite core to the plug lead that gradually breaks down. The full voltage from the coil is therefore not delivered and all manner of running problems ensue. In extremis and  if really knackered;  lift the bonnet at night with the engine running  and you will have a little light show – rather like a lightning storm.

On a technical point, when you buy something like 2 metres of copper cored plug lead also buy 4x  plug caps plus the rubber seals for the cabling as it goes into the dizzy, the centre and the  feed from the coil. “Green Spark Plug Co” does all this. These  plug caps should be of the type that have a 5k resistor (suppressor if you will) built in.

Now I hear you say,  why do I need to look out for plug caps with resistors fitted.  The answer is that folks with magento ignition systems do NOT have resistors/suppressors  in their ignition systems. If they do,  the  magnetic field generated by the suppressors  around their cabling  kills their magneto. At £600 +/- to rebuild a magneto these details are of some importance.

In 53 years of driving i have only had one coil break down and  the symptoms were that the vehicle ( a LWB in the Serengeti as it happened) would run but not accelerate.

MdeL

[Author]

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