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Lightspeed ignition Timing Light procedure.

Redbud40

Well Known Member
Anyone with the LSE ignitions that has conducted this testing procedure with the old fashioned automotive timing light. …….If so can I PM or phone call for discussion….
Specifically I’m looking for a description or explanation of the relationship between the two tests and where the marks showed up on the split case reference marker fabricated for the test….
Thanks.
Mike Red Robinson
 
Mike,

I’ve done this a a few RVs - and consider it a hard, must do for any Lightspeed install. The last one we did we found a dual Lightspeed setup with both boxes having a failed MP section. The result was the ignition's were firing at 40+ degrees BTDC regardless of engine RPM or MP. The builder did not figure this out - the guy that bought it finally called for help when CHTs were way above 400 degrees in all phases of flight. Only use of a timing light found the problem.

PM sent.

Carl
 
Anyone with the LSE ignitions that has conducted this testing procedure with the old fashioned automotive timing light. …….If so can I PM or phone call for discussion….
Specifically I’m looking for a description or explanation of the relationship between the two tests and where the marks showed up on the split case reference marker fabricated for the test….
Thanks.
Mike Red Robinson

Mike,

Can you please post what you learn? I’d like to know how to correctly do this too.

Thanks!
 
i made a pointer from tubing and attached to upper case with a clamp. Get the pointer close to the ring gear. Use starter marks to get to TDC or 25 BTDC or whatever the procedure calls for. use a sharpie to make marks on the ring gear at the pointer. Be sure to use lots of arrows on either side of mark to help find it once running. Connect light to #1 plug and have some fun. Can be hard to see in direct sunlight. MAP sensor failures are common, so wise to suck and release on vacuum hose to ensure timing is moving. Timing is least at static and should advance as you apply vacuum. Depending upon the EI config, it may not advance at idle RPMs. Never used an LS EI.

You are welcome to call for more help.
 
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I made a support structure to hold the timing light, pointer and flexible borescope camera. I tried various colored sharpie pens to mark the ring gear but had lots of trouble seeing them. Ultimately, I used different colors of torque stripe to make marks every 5 degrees so it was easier to figure out which timing value I was witnessing.

With the borescope camera, I'm able to sit in the cockpit and run the test with and without the manifold line hooked up and watch the timing change as described in the manual.

I also compared the timing light readings with the voltages coming out of the Lightspeed box and found they do indeed correlate. As such, I mounted a small jack on my panel and now can easily check the voltages at any time. Shortly thereafter, I tied that wire into my GRT EFIS and now monitor timing in real-time.

This exercise did highlight that a sudden change in CHTs was tied to the Lightspeed ignition and resulted in pulling the box and getting it repaired.

https://drive.google.com/file/d/11gRQLLHLFdnWuMkQA0OzpQM56GbiC1db/view?usp=drivesdk

Regards,
Rob
N706DR
 
A poster mentioned above to mark timing locations on the flywheel with a Sharpie... Black does not reflect light very well. Use White out to mark your timing locations and the timing light will show the position much better.
white out.JPG
 
Be sure to use an old school powered timing light, and either a high quality inductive pick-up or make a short ignition lead shunt to pick up the spark.

RmbgFX8.jpg


A bright pointer on the case spine, and white and yellow paint in the flywheel markings work well. Doing the test at night or dusk helps, be sure to run the test with and without the MP hose connected. Don't fly with the pointer mounted; test only!
 
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Parts shown below. The long piece rests on the recessed flat against the case half and held in place with the shorter piece temporarily secured by the below case bolt. The long piece extends through a slot in the front centre baffle to the flywheel. I need to temporarily remove the front centre support bracket.

I rarely check the timing with a light as I have the Lightspeed display which I have confirmed reads correctly. As a side note the Lightspeed display has a selectable rotary switch which can display timing, rpm or map. I have backup oil pressure and temperature so have enough instrumentation to get home if the EMS failed ;)

Fin 9A
 

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