OT - Timing Light adapter
Turbo Mini Forums

I saw somewhere once a device for using a timing light on a wasted spark ignition system.

It clipped around a HT lead and then had it's own false HT lead which you connect your timing light to. This basically removed 50% of the pulses so your timing light rpm was not double.

Does anyone know what these things are called and where I can get one from?

Team Racing

Hi,
I've not heard of one, I just use my timing light and halve the RPM or Advance degrees.
Have you tried Snap On or Britool?
Cheers,
Gavin :)

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yup i do the same as gavin jim .

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

website:- http://www.terryhunt.co.uk

Hi,
I've not got a dial, I've got buttons!
Cheers,
Gavin :)

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On 29th Mar, 2008 Sprocket said:

On 29th Mar, 2008 Turbo Tel said:

On 29th Mar, 2008 Bat said:
Hi,
I've not heard of one, I just use my timing light and halve the RPM or Advance degrees.
Have you tried Snap On or Britool?
Cheers,
Gavin :)

REAL men use a bog standard timing light with no dials! dials are for fairies.

Well. I will disagree with you partly

Timing lights with a dial for advance is a very usefull tool, but i do agree there is no need for the ones that tell you the RPM.

On wasted spark systems, You dont have to halve the advance degrees but you do need to halve the RPM . If its EDIS you have to take into consideration the 10 degrees standard advance

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

Never used one..

But theorising, the timing light is assuming 1 pulse per 4 rotations of the crank and with a wasted spark you get 1 pulse every 2 rotations... so everything should be doubled, rpm and advance.

But I still say you are all fairies for using them....

Terry

website:- http://www.terryhunt.co.uk

Hi,
I thought I wasn't going daft, thanks Robert :)
Cheers,
Gavin :)

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How can it read twice the degrees when the timing mark is at TDC and each spark happens before TDC, they are not addative?

To explain further, the spark only ever occurs before TDC by say, 20 degrees. Even though wasted spark systems fire the plugs twice per cycle, it still occurs at 20 degrees before TDC. Now, because the the strobe is connected to only one plug and triggered twice as many times, it is still 20 degrees before TDC.

How can it double and show, 40 degrees?

Or am i missing something and I have a super special Gunsons timing light that filters out this multiplication?

Just because it has been explained to be correct in a forum, doesnt mean its right Robert, you of all people should know this

Dont forget that EDIS has a default 10 degree advance that cannot be adjusted

Edited by Sprocket on 29th Mar, 2008.

I have to say that from logic I think Sprocket is right.

Hi,
I don't know how but it does, either that or I'm running 90 degrees of advance on my Mpi contraption
Thinking about it more, the computer in the timing light has to calculate the advance, the only way it can do that is by reference to the RPM and time elapsed from the first spark, therefore if you put another spark in mid way it will halve the time in the calculation and that will halve the advance in the calculation. therefore you'll have to set the timing light to double the figure to read the true advance.
Cheers,
Gavin :)

Edited by Bat on 29th Mar, 2008.

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Hi,
To answer the original question...

Cheers,
Gavin :)

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On 29th Mar, 2008 Bat said:
Hi,
I don't know how but it does, either that or I'm running 90 degrees of advance on my Mpi contraption
Thinking about it more, the computer in the timing light has to calculate the advance, the only way it can do that is by reference to the RPM and time elapsed from the first spark, therefore if you put another spark in mid way it will halve the time in the calculation and that will halve the advance in the calculation. therefore you'll have to set the timing light to double the figure to read the true advance.
Cheers,
Gavin :)

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

Hi,
That makes sense to you Robert?
That Brain Training game was worth the money then, lol :)
Cheers,
Gavin :)

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What filtering is being done?

Whats the difference to the timing light between a distributor ignition at 2000rpm and wasted spark ignition at 1000rpm? The light doesnt know the difference

answer is in here somewhere

http://www.freepatentsonline.com/4713617.html

Bottom line, dont buy a digital timing light, lol unless it has a 2 stroke mode on it

Edited by Sprocket on 29th Mar, 2008.

Some timing lights read double because they relate to each spark as 360 degrees of engine revolution. A wasted spark system fires twice every 360 degrees of engine revolutions (once every 180 degrees) so when the dial on timing light is set to 10 degrees it shows 20. I have a new-ish sealey timing light and it mainy shows correct timing with the odd quick reading at double, earlier sealeys show double so maybe the later ones have been modified!

-MINI CLUBMAN 1380 TURBO-

Gav covered it but heres another version
.

The timing light assumes 4 revolutions between sparks(4x360=1440) lets say that it takes 144milliseconds for the engine to do 4 revolutions - so each ms=10degrees.

OK, so if you want 20 degrees you turn the knob and the device flashes the light 2ms early..(or late?)

If you now put this on a wasted spark the timing light now sees a spark every 72ms so with the knob at 20 degrees it will flash the light 1ms early (or late?) and the timing seen is halved.

Edited by Turbo Tel on 30th Mar, 2008.

website:- http://www.terryhunt.co.uk

Team Racing

Hi,
Bound to be with that name on the box!
Cheers,
Gavin :)

VEMs Authorised Installer / Re-seller. K head kits now available!

WB/EGT gauges. Click here for customers write-up

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