You'll need to remove the oil bath air cleaner to adjust your choke. You will also need a copy of the Factory Service Manual (FSM), a 5/16" nutdriver or socket and ratchet, a 5/64" drill bit and a pair of needle nosed pliers.

Here you see the choke thermostat shaft and the alignment notch in the bottom of the choke housing. These need to be aligned at the start of the procedure.

The FSM calls for a special tool to align the choke thermostat shaft to the notch. A 5/64" drill bit will suffice, but be aware that it can slip out the notch while you are making adjustments and fall out. It happened to me so I wedged a pair of needle nosed pliers in between the exhaust manifold and the bit to keep that from happening, again.

Here I have the nutdriver on the clamp bolt. You will loosen up this bolt to adjust the automatic choke. My FSM calls for the choke to be fully closed with the throttle held about 1/3 open. So you'll hold the throttle open about 1/3 travel and use the nutdriver to rotate the lever on the choke thermostat's shaft till the choke butterfly is just fully closed. Then lock down the clamping bolt on the choke thermostat shaft. The FSM states the choke can be adjusted hot or cold.

Here I am holding the throttle open a third and making sure the choke butterfly is closed as per the adjustment. I am not touching anything else. Looks good.

The function of the choke system is to enrichen the air/fuel mixture when the engine is cold. The automatic choke is supposed to control the amount of choke applied as the engine warms up, backing it off and fully opening once all warmed up. As we can see, it is open with the engine warmed up.

Once you are done and everything is buttoned up it wouldn't hurt to double check your idle speed all warmed up. It shouldn't have changed but check it. there is no high speed idle adjustment. That is handled by a cam on the choke linkage so your base idle adjustment is what will also set the high speed idle.

Give the engine compartment a once over to see if anything needs addressed. I found a seeping head bolt during this evolution