AQ151 Inlet Manifold Heating System

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Can anyone advise me on the

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Can anyone advise me on the design and function of the Inlet Manifold Heating system on my AQ 151 B.

The inlet manifold has what appears to be heating jackets below where each of the carburettors connect.
There are brass drain plugs at the bottom of each of the jackets which are interconnected through the manifold casting.
The manifold has coolant connections just below the number 1 and 4 inlet ports to the cylinder head however the cylinder head only has a matching connection at the number 4 port. The coolant connection at the number 1 port on the cylinder head is a blind hole.
This arrangement does not allow a circulation of the coolant between the cylinder head and the inlet manifold.
Should the coolant connection at the number 1 inlet port on the cylinder head be drilled through into the coolant gallery to allow circulation?

"Tom, this is the arrangement

"Tom, this is the arrangement I have seen in other VP dual carb 4 cyl OHC engine packages (AQ140 and AQ145). In none of them does the water circulate but the open port allows the intake manifold jacket to be filled with coolant. It would appear that the heat transferred by convection to that pocket of coolant in the intake manifold is sufficient for what the designers intended, which is probably to avoid fuel condensation in the intake manifold during cold weather."