Electronic ignition

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Electronic ignition

Post by Stonehopper » 09 Oct 2016, 13:47

Finally got around to fitting the Lumenition Optronic kit.
http://www.ebay.co.uk/itm/LUMENITION-PM ... Swj0NUcLK9
Started up fine, and seems to run a little smoother on a short five mile run. Running a Xenon lamp for 33° advance at 2500rpm showed a very steady mark, much more so than with the cassette points set up. The dizzy is at its maximum travel in the annular slots (was same with points), and can only think of wear at some point in the dizzy. Ticks over fine at just under 1,000rpm, and advance rises smoothly.The lamp and chopper unit were fitted to a spare dizzy, so just a straight swop there. The old coil (without ballast) was a 3 Ohm job, the new that came with the set a 1.5 Ohm with ballast. Dwell is fixed at 65°, no more messing with points, though all are retained in a (hopefully) unlikely failure.

Image

Not cheap, but have had issues with points on the GS based around the fibre heel wear against dizzy cam. Had the same issues with a Guzzi 500. Timing would change after 150 miles. That got electronic too, and no further problems. Never had problems with 2cv points set up though.

We'll see what some mileage shows.
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Re: Electronic ignition

Post by white exec » 09 Oct 2016, 19:49

Long time since I fitted electronic ignition, but very successfully did it on several cars. Benefits included better starting, better idling, steadier pull-away under heavy throttle at low engine revs, and slightly better at high revs. Fuel consumption maybe 1-2mpg improved.

Many of the electronic systems actually feed the coil with a high-frequency input (in some cases up to 300v, but high frequency, so no damage) which operates the coil much more effciently. The result is a stronger, 'fatter' spark, of controlled duration, better at igniting the mixture.

As such, plug gaps can often be increased from the standard 0.025" to 0.040" to provide an even stronger spark. You could check with the makers of your unit whether this is so, and a reasonable way to proceed. User manual might even detail it.
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Re: Electronic ignition

Post by Stonehopper » 09 Oct 2016, 21:39

Thanks for that - I'll ask 'em. :-)

Done. The suppliers are being a little non-committal, and are suggesting fuel/air ratios are also involved in creating efficient burns (well, waddyaknow!). But searching around the net has brought a general consensus that full on electronic ignition systems, as opposed to points assisted, are quite capable of handling wider plug gaps, and indeed seem to result in better performance in terms of burn efficiency.

http://www.superbeetle.websitetoolbox.c ... on-5411037
http://www.britbike.com/forums/ubbthrea ... ber=133484
http://www.mgexp.com/phorum/read.php?1,615002
http://www.tr-register.co.uk/forums/ind ... e-confirm/
- and an overall description of systems:
http://arrc.ebscohost.com/ebsco_static/ ... YSTEMS.htm

A few nay-sayers and NIMBY's, but some solid reasoning from positive minds.
0.032" - 0.035 looks good.
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Re: Electronic ignition

Post by sandybx » 11 Oct 2016, 22:10

Well done on your conversion Derek :)
Strange high dwell compared to 57 degrees Derek and high advance too
As you say see what the mileage does :) :) :)
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Re: Electronic ignition

Post by Stonehopper » 12 Oct 2016, 09:36

Yes, the dwell is determined by the gaps between the plastic chopper blades. Without butchering them with a penknife they won't be changed!!
The dynamic timing is bang on at 33° advance at 2,500rpm. The only cause for the maximum travel of the dizzy in the annular slots that I can think of is in the relationship between the rotor arm and the pick ups in the distributor cap. But that doesn't sound likely. A/R springs and bobweights are in fair fettle - at least the same as my spare distributor - and the vacuum advance works as it should. I'm wondering what I've missed. Must study my spare a bit closer.

I also have noticed (regarding plug gaps) that although the fitting instructions do not say so, data downloaded from the internet on fitting Lumention kits, does say that standard plug gaps should be retained - .025".

"Correct spark plug gaps are also important, preferably .025 (0.6mm)"

A covering of backsides?

The response from Lumenition (Autocar)

Dear Sir,
Unfortunately there is no universal guidance on this issue that we can usefully offer.
Spark plug types (e.g. hotter v colder plugs, different tipped plugs, etc.) and spark plug adjustments tend to be specific to the engine they are fitted on. Changes can give improvements in running depending on engine temperatures, weaker or richer fuelling and the fuel being used, but I can only suggest you try it and see what happens, as trial and error is pretty much par for the course.

Alternatively if you are happy with the running on the settings you have, I suggest you leave everything where it is.

Yours sincerely
Autocar Sales Support
49-51 Tiverton Street
London SE1 6NZ
Tel +44 (0) 20 7403 4334


Another factor to add to the plug gap query, is as has been pointed out from Ken Hanna on the 2cv forum - plug gaps widen in use. Spark plugs in regular road use, as opposed to any performance/racing use, are less frequently checked and adjusted. I know from experience that poor starting of an A series from cold can often be attributed to a widening gap. Resetting the gap to standard (with points or electronic) makes cold starting easier. Still, proof of the pudding and all that.
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Re: Electronic ignition

Post by Mandrake » 12 Oct 2016, 10:12

Is that a transistor assisted system or a CDI (capacitor discharge) system ?

Transistor assisted is where instead of having the points directly switching the negative of the coil, a transistor is substituted in its place, and the transistor is then switched either by the points or by an electronic chopper. This is an improvement but you still have the conventional current build up of a Kettering coil system.

Another system is Capacitor Discharge Ignition - Dad built one for his GS that ran on it for years. The principle of operation is between sparks a high voltage DC to DC inverter charges up a large capacitor to a couple of hundred volts, at the moment the spark is due to fire a transistor "dumps" that charged capacitor directly into the coil primary all at once, thus the coil simply acts as a transformer to multiply the voltage.

The advantages of the system are - no dwell time adjustment needed as there is no "dwell" period where the coil is connected across 12v before being disconnected at spark time. No points capacitor is required at all, as there are no points to protect and the capacitor isn't required as a resonator with the coil.

Other advantages are a higher voltage spark, a much longer duration "fatter" spark, and the spark voltage is largely independent of battery voltage, making starting much easier. On a normal Kettering or transistor assisted system the drop in battery voltage from 12 down to about 8-9 volts during cranking is directly reflected by a proportionally lower spark voltage.

On a CDI system the inverter charges the capacitor up to a set voltage each cycle, lower battery voltage just means it takes a bit longer to get to that set voltage but it still reaches it in plenty of time for the next spark (especially considering you're only at cranking RPM) thus you get full normal spark voltage even during cranking.

A CDI system can also provide full spark voltage at maximum engine revs where the voltage on a conventional system is falling off due to insufficient dwell times.

Worked like a charm on his GS for years and you really could notice the easier starting on cold mornings compared to mine! He had a plug on the side of the box with two sockets so you could convert it back to conventional Kettering just by moving the plug from one socket to another... so it was quite easy to compare the performance both ways.
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Re: Electronic ignition

Post by white exec » 12 Oct 2016, 11:02

I built and used two or three Electronize capacitive discharge electronic ignition kits back in the 70s/early 80s. You could buy these ready built, or as a kit of parts. Delivered a lovely high-energy long-duration spark (almost 1cm long, on test).

The kit was originally designed to be used with existing distributor points, and reduced the current loading on the contact breaker to about 30mA iirc - so no burning. Unit also had a changeover switch, which simply knocked the entire device out, and connected points straight to coil, as per standard, in case of failure - which it never did, unlike some competitor and OE products.

I fitted these to an Austin-Morris 1300, two Dolomite 1850's, a Rover 2000TC and a 3500S. The benefit for the V8 was considerable.

After the initial fitting with the contact breaker on the V8, I ditched the points, and replaced them with a Hall-effect inductive pickup - someone's plastic ring with embedded metal inserts slipped over the cam, and a V3 (microswitch)-style proximity detector from R.S. All this fitted easily on the CB baseplate. Ditching the points really made the V8 sing, and no more heel wear!
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Re: Electronic ignition

Post by Stonehopper » 12 Oct 2016, 11:46

Electronics are a black art to me. What goes on inside black (or otherwise) boxes is unknown. But I did have an electronic system fitted to a 2cv Charleston years ago which was a points assisted device with a switch to revert to non-electronic IIRC (is this plausible?). Never could tell the difference in performance, but as it was fitted - it stayed switched 'in'.

This Lumentition kit is of CDI nature, switched by a lamp and chopper in place of contact breakers. Interesting Kettering has been mentioned, as a coil as used in the Kettering system is also used - but without points and associated capacitor.

Interesting description (for this numpty) of CDI ignition here:

Last edited by myglaren on 12 Oct 2016, 15:47, edited 1 time in total.
Reason: Youtube link fixed
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Re: Electronic ignition

Post by Stonehopper » 13 Oct 2016, 16:37

Thanks Myglaren - I hadn't spotted it was duff.
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Re: Electronic ignition

Post by xantia_v6 » 13 Oct 2016, 17:08

Electronic ignition is not really a black art, but there are many myths and misunderstandings.

One fundamental thing to remember is that the fuel mixture only needs to be (and usually only can be) ignited once, so having extra sparks after the mixture is ignited a waste of effort. If standard ignition is working well, you won't get any improvement in performance whatever you fit.

CDI systems generally give a very high energy spark, but of very short duration. This is excellent for firing rich mixtures and will still spark with fuel or carbon fouled plugs. CDI does not work so well in modern engines which run lean mixtures, as the spark is to quick for reliable ignition.

Most modern high energy ignitions systems are inductive discharge (with dynamic dwell control) which gives a longer duration spark which is not as intense as a CDI spark, but is better at igniting lean mixtures.
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Re: Electronic ignition

Post by myglaren » 13 Oct 2016, 17:11

Stonehopper wrote:Thanks Myglaren - I hadn't spotted it was duff.


Not duff exactly, it was just an url to click rather than the embedded video.
No big deal but simpler for anyone wanting to view it to have a visible video.
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Re: Electronic ignition

Post by Stonehopper » 13 Oct 2016, 20:50

And there was me just getting a handle on CDI ignition! And along comes inductive discharge . . .

Any more 'dementers' coming this way?
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Re: Electronic ignition

Post by myglaren » 13 Oct 2016, 20:53

Those inductive discharges are sneaky little buggers, ain't they?
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Re: Electronic ignition

Post by Stonehopper » 15 Oct 2016, 10:38

How do you 'fix' that url link to show as a video window Steve? Tried the url and you tube buttons but still comes up as a line of text.
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Re: Electronic ignition

Post by myglaren » 15 Oct 2016, 10:58

instead of: https://www.youtube.com/watch?v=Bc7wPH-sbGg
cut out everything before the = sign

to: Bc7wPH-sbGg

then enclose it in the YouTube tags: [you tube] Bc7wPH-sbGg [/you tube] (broken her for demonstration purposes)

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