You don't have that carburetor on a Lp manifold, do you?
The truth is, I don't know if a Lp manifold was offered for the OHV 206, but there was a separate Lp manifold for all the older Lp MM tractors.
The reason I am asking is most gasoline manifolds are designed to transfer exhaust heat to the intake manifold to combat icing. The regular Jetstar manifold acutually bolts the two together just above the carburetor.
Most Lp manifolds do not have any connection between the intake and exhaust manifolds, to keep the Lp gas as cool as possible before it enters the cylinder.