How to Tune a Bendix Carburetor

eHow may earn compensation through affiliate links in this story.

Things You'll Need

  • Screwdriver

  • Tachometer

Tuning a Bendix carburetor is a job you can complete in just a few minutes. The Bendix carburetor has two adjustment needles on the top of the carburetor. The low-speed adjustment needle is near the mounting bolts in the back, and the high-speed adjustment needle sits just forward of the low-speed needle. The idle stop screw is off to the side of the high-speed needle.


Step 1

Start the engine and allow it to warm up for a few minutes. Shut the engine off and turn the low-speed and high-speed adjustment needles clockwise with a screwdriver until they are closed, without over-tightening the needles.

Video of the Day

Step 2

Turn the low-speed adjustment needle counterclockwise 1-3/4 turns. Turn the high-speed adjustment needle 1-1/2 turns counterclockwise.


Step 3

Start the engine and let it warm up for a few minutes. Turn the low-speed adjustment screw clockwise until the engine starts to stall out, then turn it back counterclockwise one-quarter turn.

Step 4

Turn the high-speed adjustment needle clockwise one-eighth turn and run the engine at high idle for a few minutes by moving the choke cable forward. Move the choke back to idle speed to check the engine performance.


Step 5

Repeat the adjustments in Steps 3 and 4, revving the engine and letting it settle into low idle until you reach the optimum performance of the carburetor. Place a tachometer lead wire on the negative ignition coil post and attach the other lead wire to the engine block.

Step 6

Turn the idle stop screw until it reaches between 2,200 and 2,600 rpm on the tachometer. Readjust the low-speed needle until it is running smoothly.

Step 7

Remove the tachometer from the engine and turn the motor off.


To avoid burns, be careful of touching the barrel of the Bendix carburetor while the engine is running.