C1 engine analyzer

[Al C.]

My '58 is not running so great - so far I've identified that the centrifugal advance is not making spec, I think the springs are too strong. I'm beginning to think I need to check the cam lift.
But I wanted to verify all the ignition works first. So I started looking at how to rig an old-fashioned engine ignition analyzer. This is in the too good to be true department - my Mac laptop has really good audio processing - with a suitable protective resistor connecting it to the coil primary (across the points, and a freeware audio processing program, total expenditure $0.00 and some time, VOILA:
... Al '58 245hp
look at

[Rob M.]

Re: C1 engine analyzer

Al,

Cool, but what can you know learn from this picture?

greetings,
Rob.

[Edward Boyd]

Re: C1 engine analyzer

Looks like an EKG strip showing degression to asystole.

[Al C.]

Re: C1 engine analyzer

Rob - The photos I posted show a "good" single waveform and a train of eight (I'm still working on how to ID which is #1); the lower trace is lowpass filtered to peel away the ringing, easier to see the underlying waveform. What can we learn? Now look at this pair of waveforms. Something is causing general breakdown (left picture) on one plug some few seconds after coldstart. On the right, at warm idle, a plug is not firing for almost half a millisecond afterr the points have opened. Now, I'm madly trying to find a reference for BAD waveforms to diagnose my engine.
Regards, ... Al '58 245hp

[Robert Willis]

Re: C1 engine analyzer

Hmm. Looks like a cross fire between #8 and #6 wires . It's been 30 years since I looked at one of those old scopes. I'd check the wires first . Is it running a little hot ? Maybe a head gasket leaking and fouling #s 6 and 8 plugs ?

Bob

http://members.kos.net/willisb/