1980- 1984 vintage for a full crank side starter electronic ignition yours is.
G4 carburettor has grey knurled idle adjuster knob. Very similar LM hasn't got this idle knob.
The poppet valve with A B C on it is normally white I believe, but the Vortex mower's version of the LM carb is modified with a black one instead and is aligned differently to the regular white poppet version on all other models.
Early G4 carbs have ether no primer button, or a remote primer button situated away from the carburettor with a grey float chamber cap.
I'm not sure whether the white float chamber cap with the integrated primer bulb was introduced mid way with the G4 or only came out with the LM carb in 1980.
