If you can find any more numbers you could try plugging them into
Sears Parts Direct. I tried it with the number you gave, and
a bunch of Tecumseh looking carbs came up.
https://www.searspartsdirect.com/search?q=640-12
If that model has electronic ignition, I understand parts are either
non-existent or would cost 10 times what the motor is worth…..
might be a reason it was on the side of the road!
Prepare to be boarded!
