slantsixdan said

No, the manifold heat control valve counteracts the tendency of vapourised gasoline (like any other sprayed/expanding liquid) to absorb heat from its surroundings. That's bad in the case of the intake tract, because it causes the gasoline to fall out of suspension and puddle/pool along the intake manifold walls, making the engine run worse; use more fuel, and crap up the oil with unburned gasoline. This valve is best present and working no matter whether you live in Alaska or Florida; it has its job to do even when the engine is fully warmed up. This Jam Handy cartoon from 1935 is a real trip to watch, and at 5:37 it explains (in very simplified terms):



The spring absent in the OP's photo is an anti-rattle spring. It can be replaced by an appropriate-length coil spring from a good hardware store. It just needs to keep light tension on the valve shaft—not very strong tension which would bind the shaft and prevent it turning easily.

As to the secondary air injection port at the back of the head: there used to be a factory blockoff plate, part № 3751 249 and gasket 4275 834 (the gasket is available aftermarket; the plate is not, that I know of, but with the gasket you ought to be able to get someone to water-jet or laser-cut you one from suitably thick steel).

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