chasing spark 74 cuda

[CU-DUH!]

Did you change the reluctor? when you point the rotor at # 1 on the distributor a tooth on the reluctor should be just passing the pick up. The reluctor has two locations depending if it's turning clockwise or counter.

reluctor position on #1

[CU-DUH!]

Roseville sells only good parts so that is an option .
Hold the end of the coil wire near ground & crank the engine , you should have a blue spark ,not yellow, that will jump at least 1/4 " , if not the wire  or coil is bad .
You should be able to test the center terminal on the cap with an ohm meter  for continuity but it will not be zero Ohms as the carbon terminal will have resistance .

so... made a video to show just what you mentioned....but can't load it here...bummer... from what you described is exactly what's happening, little yellow vs blue.... oddly the coil is new from Roseville???

[CU-DUH!]

https://youtu.be/_uLH4jIhuVs

[Chryco Psycho]

Talk to Dave , anyone can have a bad day building products !

[CU-DUH!]

Finally solved this...turns out it was the ECU. Good friend has a distributor testing machine, with new cap and rotor, we mounted it up, all the signals came up .. even the vacuum advance works  Next, did a mock ignition system setup including ballast resistor, coil, plug, ECU.. got no spark. He had a similar ECU we tried again...bam ....spark!! Retested with a newly ordered  ECU and all good now. Apparently, my inline tester is misleading. It will flash at a low voltage, and not what is actual required!

[HP2]

Glad you were able to find the source of the problem and get it resolved. Its awesome you were able to get someone to work through an actual analysis of components.

I've never used an inline tester, but it sounds like they aren't the most reliable diagnostic tool.