Why do we have 2 sets of points?

[jordo]

I am going to investigate my stag not running or even starting now, today. I had a quick look last night and am unsure why there are two sets of points. When i opened the second set with the ignition on there was a small spark as i would expect. The first set looked as if they were closed. don't they both need to be open to create a spark. I couldn't get the first set to spark even when holding the second set open.

It was late so i never turned the engine to check gaps i literally went out to charge the battery and started getting involved.

The haynes manual doesn't explain why there are two sets of points.

Thanks for any info.

[mad cyclist]

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so the dizzy only has to travel twice as fat?, think its to get a more even spark, oh and triumph thought it would be another way of whileing away our time in 20 years!

my advice would be go for electronic, its easier and better for unleaded....

rgds Nick

obviously not an expert

[jordo]

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thanks

[mjheathcote]

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If I recall two sets of points are used to get the optimum dwell angle required for a V8, that you can not get with one set. So when you set them there is a slight difference for when they open on the cam creating a longer dwell angle.

You can run with one set, infact the first early stags only had one set fitted. Same with the Rover V8's some had two sets, some only one.

[NickA]

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mjheathcote wrote:

If I recall two sets of points are used to get the optimum dwell angle required for a V8, that you can not get with one set. So when you set them there is a slight difference for when they open on the cam creating a longer dwell angle.

What he said it's to increase the dwell. Bugger to setup properly, and have you seen the price of them? :shock:apparently made by Aston Martin

http://www.ldparts.co.uk/shop/shop.p...e6eecd91e53d99

[John Wright]

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It takes a while for the magnetic flux to build up in the coil so that when the points open the rapidly collapsing flux can create the high voltage in the coil secondary to create the spark. With a V8 there are 8 lobes on the distibutor cam and it is therefore difficult to provide a sufficiently long time for the energy build up. By putting in two sets of points in parallel and displacing them so that one opens slightly before the other, the time period can be extended. The time period obviously varies with engine revs, and so it is usually expressed as the angle for which the points are open (dwell angle). If the dwell angle is too short, the high rev performance is affected as there is insufficient time for energy build up in the coil resulting in a weak spark. Electronic ignition overcomes all these problems, and provides a much better spark at (all revs) than even a properly set up distibutor can.

Happy driving.

John

[jordo]

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Thanks

I am going to try a coil and condensor first as i have just had to shell out £180 for a new compressor for my range rover.

[tedlit]

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^^^ What John said.

That said, I'm perfectly happy with my single point setup.

Until the Pertronix kit arrives.