VW Bug Tech Articles

- Solex 34 Pict 3 Carburetor Tuning -

• Things to do before tuning
• Check or adjust the Valves
• Check the Points (if you have them)
• Check and set the Timing


• Inspect the choke
• Warm up the engine
• Remove the air cleaner (either paper or oil bath)
• Choke butterfly should be vertical
• If its not vertical, keep warming the engine
• If it still doesn't go vertical, adjust the choke



• Now on to the actual tuning of the carb
• Tools needed for adjustments
• Large sloted screwdriver
• Small sloted screwdriver
• Tachometer - either in the car or an inductive pickup


• Main parts that need adjustments
• Fast idle screw - long thin screw that is on the throttle arm
• Bypass screw - large screw (rounded head) on the drivers side
• Volume screw - small recessed screw (flat head) on the drivers side next to the Bypass screw

• Adjust the Fast Idle screw so that it just touches the bottom of the stepped cam (below the first step) and turn it 1/4 of a turn in - do not go farther or the adjustments will not be correct
• Set the Bypass screw to about 2 1/2 turns out (gently bottom the screw out and then back it out)
• Set the Volume screw out exactly 2 1/2 turns (gently bottom the screw out and then back it out)
• Start the car and adjust the Bypass screw until the engine idles at about 850 RPM
• Adjust the Volume screw to fastest idle (turn screw no more than 1/2 turn in either direction)
• Adjust the Volume screw until the RPM drop about 25 RPM (slight audible slow)
• Readjust the Bypass screw to set the idle back to 850 RPM


• Drive your well adjusted carbureted engine around!