Here’s my favorite method for adjusting an electric guitars pickups for a balanced tone, no feeler gauges or micrometers needed:
1. Set the pickups so that they are level with pickguard or pickup rings. Adjust the polepieces (if possible) so that they roughly match the radius of the strings.
2. Plug the guitar into a clean amp and turn the amp on. Do not injure yourself completing step 2.
3. Select the bridge pickup and slowly raise it (a turn on 1 screw, then the other) while strumming the guitar. You’ll notice the tone changes as the pickup moves, gaining output and compression as it gets closer to the strings. When it gets too close, you’ll hear a loss of sustain and possibly some out of tune notes due to the magnetic pull of the pickups.
4. Play with the bridge pickup height until you are happy with the tone.
5. If the strings seem out of balance, lower the side of the pickup that seems “hot”.
5. Switch to the neck pickup, and adjust it until it matches the bridge in volume (this will probably be lower than you’re used to seeing). If the bridge pickup is very loud compared to the other pickup(s), you may need to lower it a bit for balance. This gives the neck a much woodier tone than the typical height, and lets you select pickups for tone without worrying about volume loss.
6. Set the middle pickup (if you have one) to match the bridge as well.
I’ll repeat these steps with distortion, just to check the tone. Once you find a pickup height you like make sure to make a note of the distance between each pickup and the strings, otherwise you’ll be setting everything from scratch if you raise or lower the action….