How to Adjust the Automatic Choke on an Aircooled Volkswagen (VW) Beetle
The engine must be cold to make this adjustment., Remove the air cleaner. , Find the automatic choke., Pull the throttle arm on the left side of the carburetor down to free the cam (little step arm) that the screw at the top of the throttle lever...
Step-by-Step Guide
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Step 1: The engine must be cold to make this adjustment.
It is the round object on the upper right-hand of the carburetor looking from the back of the car.
There is a wire coming to it from the positive side of the coil.
Check this with a trouble light for voltage when the key is on.
The choke is held in position by a triangular ring clamp and three screws so it can be loosened and rotated for adjustment. , With the engine cold, the butterfly valve should be closed.
As the engine warms up, the coil voltage heats an element inside the automatic choke, causing a bi-metal spring to uncoil, opening the butterfly valve, and moves the cam to reduce the idle speed. , When cold, the little screw at the top of the throttle arm should now rest on the top step of the stepped cam.
This sets the hi-idle, which is needed together with the choke on a cold engine to provide sufficient idle speed to keep the engine running until it warms up fully. ,, Turn the choke element clockwise until the butterfly is standing straight up.
Then turn the choke counterclockwise until the choke butterfly fully closes (not too tight). ,, As the engine warms up, make sure that the butterfly opens until it is standing fully open when the engine is fully warm.
If it doesn't fully open,put your finger briefly on the ceramic of the automatic choke and see if it is hot.
If not- you need a new one.
Try it again in the morning and see if it opens enough to drive it.
Check that it is wide open when warm.
Re-adjust until you get it right. -
Step 2: Remove the air cleaner.
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Step 3: Find the automatic choke.
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Step 4: Pull the throttle arm on the left side of the carburetor down to free the cam (little step arm) that the screw at the top of the throttle lever rests on.
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Step 5: Release the throttle arm so that the return spring snaps it back.
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Step 6: When cold loosen (not remove) the three screws on the right side that hold the choke in place.
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Step 7: Keep your eye on the butterfly valve in the carburetor throat.
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Step 8: Tighten the three screws that hold the choke in place.
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Step 9: Start the engine with the air cleaner off.
Detailed Guide
It is the round object on the upper right-hand of the carburetor looking from the back of the car.
There is a wire coming to it from the positive side of the coil.
Check this with a trouble light for voltage when the key is on.
The choke is held in position by a triangular ring clamp and three screws so it can be loosened and rotated for adjustment. , With the engine cold, the butterfly valve should be closed.
As the engine warms up, the coil voltage heats an element inside the automatic choke, causing a bi-metal spring to uncoil, opening the butterfly valve, and moves the cam to reduce the idle speed. , When cold, the little screw at the top of the throttle arm should now rest on the top step of the stepped cam.
This sets the hi-idle, which is needed together with the choke on a cold engine to provide sufficient idle speed to keep the engine running until it warms up fully. ,, Turn the choke element clockwise until the butterfly is standing straight up.
Then turn the choke counterclockwise until the choke butterfly fully closes (not too tight). ,, As the engine warms up, make sure that the butterfly opens until it is standing fully open when the engine is fully warm.
If it doesn't fully open,put your finger briefly on the ceramic of the automatic choke and see if it is hot.
If not- you need a new one.
Try it again in the morning and see if it opens enough to drive it.
Check that it is wide open when warm.
Re-adjust until you get it right.
About the Author
Melissa Peterson
Professional writer focused on creating easy-to-follow practical skills tutorials.
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