9 old tools almost nobody uses anymore

A timing light is useful even on modern engines with no spark timing marks. I used my timing light to quickly confirm the coil pack was bad in my 2002 Chrysler 3.8L engine. I just clamped it over each plug wire and found two off the same coil didn't constantly flash it. Much faster than using an inline spark tester. Listening close, I could hear faint ticking sounds inside the coil-pack. I got a new timing lamp with adjustable delay so you only need to adjust until the TDC damper mark aligns with 0 deg on the tab then read advance degrees on the lamp. It also measures rpm.

For those still running points, as the article explains you set the gap only to get close, then read "dwell" with engine idling. That is the fraction of time the points are closed to recharge the coil between sparks. Not needed with electronic ignition. Chrysler's system is just a transistor with no dwell-control other than the rough control the ballast resistor provides. The slightly later GM HEI and Ford TFI have electronic dwell control so need no ballast, as does Ignitor II and III.