It is used to keep the manifold at a constant temp, for more stable jetting no matter the weather.

See Suction Pipe - one hose is for heater, the other for manifold.

The water heated A15 inlet manifold has an external fitting on the side, facing towards the front of the car.
This is attached via a rubber hose to another outlet which comes off the front right side of the motor, just next to where the lower radiator hose attaches onto.

It is used to warm the carby for better operation when cold.

Cheers, James.

I thought it (manifold) just becomes a portion of the circulating current through the head. I do not think there is an outlet on the manifold.

From memory only the twin 'SU' manifolds feature an external water fitting.

I think it is for warming the inlet manifold and not cooling it, but not 100% sure as I've not seen one for 20 years or so

Hi all, i have a H89 head with coolant ports and a downdraft manifold with the ports to match. I am wondering where the water travels (from the heater, straight from the radiator, block etc..) has anyone got a photo of the fitting on the manifold where the water exits? If so, where does the water go from the manifold?

Thanks in advance