Strange problem here. While timing my '74 2.L today I noticed that the timing light was firing but It was not illuminating the timing mark on the fan at idle speed, no matter where I set the degrees knob on the light. However, if I slid the pickup along the ignition wire, closer to the spark plug, I could then see the timing mark as normal. Sliding it back to about mid wire and again it disappeared, even though the light was flashing. I then reversed the pickup on the wire by 90 degrees and the mark showed up normal anywhere I positioned the pick up along the wire. What is going on here?

I did notice that the flashing strobe looked a bit erratic on number 1 cylinder in comparison to the other three. Do I have a bad wire, coil, sparkplug, or is it my timing light. The car is running nominally. Also, the timing mark is always visible when checking the full advance at 3500 RPM no matter how I have placed the pickup. This problem just seems to be when checking the timing at idle speed.

Very baffled. Input appreciated

Ansbacher
Tampa Bay, FL

Correction to above. "90" should have read "180". It's all moot now anyway as I now know what was wrong. I did not realize that the pickup on the timing light is directional. I had the marked arrow going in the wrong direction along the ignition wire. It must point toward the sparkplug. Guess I have been lucky all these years when clamping it on- until today. Oh, well....

Ansbacher

Didn't know those were directional either. I'll have to check mine.

Ohm meter on the ignition wires.

MSD multi-discharge ignitions can also mess with some timing lights.