TIMING LIGHT - PULSE CANCELLING

[MRSSPOCK]

I wonder does anyone know if such a timing light exists, which enables, let's say, every second pulse to be ignored.

For example, imagine a conventional type Kettering induction system, with the inductive pick up clipped on to the the central lead connecting the ignition coil to the distributor, of a four cylinder engine.

Then suppose you want the strobe light to flash on every 3rd spark, ignoring the other 3 inductive pulses.

I know people will say, why not just move the pick up to the relevant lead, but my actual scenario is not as described as above, but that description makes it easier to explain.

Has anyone ever heard of such a timing light?

I imagine not.

For those who already know about the wasted spark systems, here is what I really have to deal with.

What I want to do is eliminate the wasted spark inductive pulse, so that I can use a timing light which gives only one pulse per combustion cycle and not two.

Thanks

 

[VEBill]

I've not seen one.

You could paint extra reference marks, offset from TDC by the desired fraction of 720°, on the crank pulley.

Some timing lights, the expensive ones, have the digital offset. I wonder if they have enough range to do what you need?

From an electronics point of view, it wouldn't be a very difficult project to design a circuit, or program a micro, to do what you wanted.

One slightly tricky detail would be have a mechanism (user interface) to switch to the other every-2nd pulse, if it's locked onto the wrong one.

If using a micro, another detail would be keeping high voltage spikes out of the micro. It's the sort of application where one would need more than the usual amount of protection circuitry.

Good luck.

 

[MRSSPOCK]

Thanks VE1BLL

The problem is when trying to view an advance curve while revving the engine.

With the extra set of information it all gets a bit messy, especially since the second set of information isn't even a prcise 180° phase shift.

Maybe chopping off half of the timing disc might be the easiest option

 

[Compositepro]

"Maybe chopping off half of the timing disc might be the easiest option". Or paint it black.
I have a hard time envisioning your problem. The opposite side of most timing discs looks the same as the side with the index mark except without the mark, so the extra flash only dims the mark slightly without causing any visual confusion. This is likely why there are no timing lights with the feature you request. It certainly would not be difficult for a company to add a divide by two (or three) function to the light trigger circuit. I guess there is no market for it.

 

[MRSSPOCK]

I totally agree, a standard timing pulley wouldn't be a problem, but it's a timing disc I'm referring to, similar to this one.

I just thought that maybe back in the old days of crypton-tuning, such a device might have been produced for some reason, possibly to check distributor eccentricity or something.

Just have to get the paint brush out

 

[Compositepro]

The picture is very helpful in understanding you problem. I've never seen such a timing disc. Masking tape will solve your problem and can be removed afterwards. There must be a reason for the second scale.

 

[dicer]

Is this engine efi?

 

[MRSSPOCK]

@dicer No. Early 1900's single with electronic ignition. The wasted spark trigger signal is not a precise 180° from the non-wasted spark, because of the trigger bar installation. Since it doesn't need to be correct, there is no reason to fix it. We just would like a clean strobing technique. We're just going to paint over the non relevant index marks, which is non a problem. I just thought of such a light existed and was available on ebay, that would be an even nicer fix.