In an age of $10,000 diagnostic tablets and cloud-based engine analytics, it is easy to forget that some of the most useful tools in a garage are analog, affordable, and nearly indestructible. Enter the Gunson Digimeter 320 .
Start the engine. The manual instructs you to read the scale marked "DWELL" (0-60 degrees). For a 4-cylinder, spec is usually 60° ± 3°.
The original manual is laid out in dense British technical prose. In PDF form, you can hit Ctrl+F and type "dwell" or "no spark" to jump instantly to the diagnostic flowchart. Gunson Digimeter 320 Manual Pdf
By hunting down the , you aren't just finding instructions—you are preserving a skill. You are learning why dwell angle matters, how to measure voltage drop without a graphing calculator, and why every classic car owner should own a simple, analog meter.
The original manual’s wiring connection diagram is tiny. On a smartphone or tablet, you can zoom 400% to see exactly where the red crocodile clip goes (hint: To the coil’s CB terminal, not the battery). In an age of $10,000 diagnostic tablets and
Set the rotary switch to "Dwell" (position C). Connect the black lead to ground, the red lead to the coil’s low-tension terminal.
The needle reads 35°. The PDF’s troubleshooting guide tells you: "Low dwell angle = points gap too wide. High dwell = points gap too tight." You adjust the points, re-check, and the misfire vanishes. The manual instructs you to read the scale
So download the PDF. Print it out. Laminate the calibration page. And keep that Digimeter running for another 40 years.
Save the PDF to your phone’s local storage. The one time you need the RPM multiplier, you won’t have cell service in your buddy’s barn.