Ferrari Mailing List: Nerd talk, induction pickup

[Richard Lindsay (richardolindsay]

Hey Gang,

Anyone made an inductive pickup for evaluating spark profile? I have an old timing light with the inductive pickup that one places around a plug wire. I'm thinking of cutting it off and converting it into a probe for my oscilloscope. That way I could look at the spark profile without feeding a zillion volts into my scope (which would certainly fry it since I don't have a high tension probe). Any of you tried this?

I'm also thinking that the second trace of the scope could monitor the TDC sensor.  Together, the time difference beyween the two signals would provide a direct measure of ignition timing and advance profile.

And to bore you completely: A cold engine's charge is ignited by the inductive component of the ignition. That's the fat, hot, part needed to ignite a wet charge. Once the engine is hot, the charge is all gaseous and ignites by the capacitive impulse that lasts under a millisecond. It may be a trivial difference because dry and wet charges burn at different rates, but the inductive component happens noticeably after the capacitive component. Hummm. So there is no single ignition timing, only an average value.

Wake up now.

-rick, pondering