I started around 1963 when a pack of matches was a tune up tool.
We used the thickness of the paper match to gap the plugs and used the match book cover to gap the points.
Then while the engine was running loosen the distributor turn left till it stumbled turn right till it stumbled and set in the middle off the two.
We didn't have much money as kids.
Nice one! I bought a cheapy handheld tach-dwell meter way back when, and still remember the rule of thumb for dwell: 60° for a 4-banger, 40° for a 6, and 30° for a V8. (In each case, divide 360° by the number of cylinders, and take 2/3 of the result. Never worked on a 5-cylinder, but by the formula its dwell would be 48°. Likewise, a 3-banger would be 80°.)
In practice, the manufacturers' specs varied from this a bit. I think Chevy inline 6s called for 37°, and Japanese 4-bangers specced 52°+/- 3°.
A typical tune-up involved:
- Clean and regap the plugs (typically 0.030").
- Change the points and condenser, and gap the points. (Don't forget to lube the rubbing block on the points!)
- Check the dwell, and adjust as required. (GM V8s were a joy - with the little pop-up window on the cap, the points could be adjusted with a hex key while the engine was running.)
- Check the timing, and adjust as required. 4° BTDC seemed pretty common.
- Set the curb and idle speed, typically to 750 RPM. The later carbs had the anti-dieseling solenoid too, and sometimes there was an adjustment for fast idle.
- Set the mixture, typically 1/8 to 1/4 turn to the lean side of best idle.
Hotly debated questions of the day:
Do the plugs every 6 months, or go a full 10,000 miles?
Change the condenser every time?
Cap and rotor - change with plugs, or every 2nd time?
Those were good days!