Club Cobra - Engine dies in Friday evening traffic...

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Quote:

Why can't MSD and others make one that is as durable and dependable as the Ford unit???

Money, money, money!!!!!

I'm not convinced it was the coil. It may strand you again.

If you don't have a spark tester, get one. By spark tester I'm talking about a thing that almost looks like a spark plug with a grounding clamp on the side, and no electrode. It takes about 20K volts to jump the gap. They are $10-15 at auto parts stores. Then carry it and a spare spark plug wire and coil wire that are known to be good. You can eliminate a whole bunch of parts in a hurry with this simple tool. Wish I would have had one with me when I started down a similar road.

Another way is place a short ht lead into the coil tower, slip some clear tubing over the other end, and leave a half inch gap inside the tubing and connect the coil lead intop thje other end. This way you can start the car and observe the sparks. If the spark stops before the engine comes to a stop, it's coil or ignition related. If the spark is still going as it dies, it's fuel related. If the spark stops, put a test light across the coil, and see if it stops flashing before the engine comes to a stop. If it doesn't, it's the coil. You can also try and put the coil in a oven, then test it for spark.
JD

You can't teach an olddog new tricks, but can learn new tricks from an olddog. Good idea on the spark tester. I was going to fabricate something similar myself, but heck, if I can just buy one for a fist full of dollars, why waste my time.

Well, I'll keep you posted if I get stuck again, but based on past experience and the failure mode, I'm confident it was the coil.

Dd

Quote:

Originally Posted by CobraDan (Post 1204826)

The usual cause for a failing or failed coil is overheating. This is usually caused by spark plugs with too large a gap, which causes excessive KV to jump the gap. The bigger the gap, the bigger the jump, and the more power necessary to initiate.

A coil that is failing will cause a low-spark intensity. When this happens, the combustion is not efficient, and a driver will experience a drop in power. A weak coil will also have a more difficult time jumping the gap in the plugs and will also have the possibility of no spark in lean fuel conditions within the cylinders, resulting in an engine misfire. Rich conditions are conductive and promote ignition sequence, while lean conditions require more voltage to jump the gap. If the coil is too weak there will be no spark.

Certain coils are designed to operate at 6 volts rather than 12 volts. They are designed this way to prevent heat build-up in their particular situation. These coils require a ballast resister in line that drops the voltage.

A total coil failure will cause a no spark, no run condition. This can be diagnosed by pulling off one of the spark plug wires at the point at which it is attached to the spark plugs. In the event of a coil on plug situation, remove the two 10mm bolts and pull the coil off of the plug. Install a tester spark plug in either unit and lay it on a good ground on the engine. Have a helper attempt to start the engine and observe the plug for a good spark. If you do not see any spark, the coil is bad.

Gee that's a lot of work I usually just get one of my kids or if they're not available a neighbours kid to hold onto the plug lead - if they squawk a bit or leap about like an idiot I know the coil is fine !:eek: :LOL:

Hello all,

I can also tell my story about the coil

In the end of last year I realized a more and more worse starting behavior of my engine. In the beginning of this year that behavior was so annoying that there was something to do. Especially at hot engine conditions I had enormous problems awaking my engine.

The situation was so, that the ignition seems to be completely dead while the starter motor is running. At the time when the starter motor was currentless the ignition worked and the engine started promptly.

An other worse behavior was under driving conditions. When I drove downhill, without load, I realized bucking (In german we call that behavior “Schieberuckeln” ).

As the fuel system was O.K. ( new pump, clean carburetor, new filter, new hoses ) I thought I should buy a new coil.

Furthermore my coil was very old ( 20 Years ? ) and mounted horizontal.

So I decided to buy a new MSD high vibration coil ( 8222 with epoxy) and a new ballast resistor.

After installation of those new parts – the sun was shining.

Everything runs as it should, starting behavior is fine ( no matter if cold or hot ), idling is much better and this bucking is also eliminated.

That’s my experience.

Regards

Werner