Air gap manifolds in cold weather

fishy68 said
All manifolds (even an Air-gap) have the water coolant passage. That's not for heating the manifold. It's for connecting the water coolant passages on the heads and providing an outlet to the radiator. Magnum heads have no exhaust heat crossover like LA heads so it doesn't matter what manifold you use although a manifold that's not an Air-gap style might be slightly better cause the oil being splashed on the bottom side of the plenum will heat it some.

Hi Fishy,
If you have a look at the picture on the summit page there is an extra coolant passage that runs under the manifold where the carburetor sits for heating.
The one you're talking about is where the thermostat sits, I know every manifold has this.

I had a car that used coolant for heating the manifold but the passages were blocked and it was a total pig in the winter.

Thanks.