heated inlet manifold on 1275 - worth connecting or not?

[paulr]

hi all,

our single carb 1275 has the facility for a heated inlet manifold but currently it is not connected - is it worth connecting and if so be grateful if someone could please guide me on where the connections to it run to and from - if it is not worth connecting - great - one job off the list

Paul

[Stuart]

Best left not connected unless you drive around a lot during the winter during freezing conditions.

[Rich]

Mines connected, though I think I'll be bypassing it until it gets chilly. I run the piping from the top take off (clutch end of the cylinder head), through the manifold and into the heater.

[Jon]

I have been told by someone who has a lot of engine design experience that the 'heated' inlet manifold is a misconception. It is actually a cooled inlet manifold. The water passing through the rest of the block and cylinder head is removing heat from the engine. The inlet manifold is cooled to some extent by the fuel/airflow through it, but generally reaches a temperature very close to that of the rest of the cylinder head. The manifold gasket could be assumed to insulate it a bit, but the studs/bolts/nuts etc are a direct heat transfer path. Thus the water passing through the manifold pipe is far more likely to be removing heat than adding it. The manifold pipe shouldn't be connected in series with the heater as the valve that stops the flow to the heater also stops the flow through the manifold.
Whether this is correct or not I don't know, but it sounds plausible.

[manifold]

Jon,

the heater outlet on the Mk3s (or metro) doesnt have a valve to alter flow whereas mini based heaters do.

[paulr]

thanks all sounds like a 50/50 issue - might try it at some time but certainly seems like not an essential - thanks