Zenith HF3K Carburettor and Choker Device

We are looking for information on the above carburettor. The carburettor has a model number or part number of 'HF3K' cast into the body. Cast into the float chamber lid is the number 08 (year of manufacture??) made by Zenith, USA patent.

The demountable 'choker' device appears to have a solenoid, perhaps an early form of automatic choke, however there is also a manual lever in the event the solenoid doesn't work. I think there should be a spring within this assembly to hold the choke open but this appears to be missing. It would appear that the 'choker' device would be mounted on the carburettor loosely with the mounting boss and bolt to secure to the engine body.

We intend to use this carburettor on a future project but would be interested to hear if anyone knows the original application for this interesting unit.

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