Air gap manifolds in cold weather

scrappydoo said
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.

Hum... I can't really see an extra coolant passage running under the plenum unless it's that threaded hole in the side of the plenum. It would need an outlet somewhere. Maybe on the side not pictured. Doesn't say anything about it in the description. That must be a fairly new design if it is designed that way, or I'm behind on the times LOL.