Hello. Just picked up on this query about the crossflow heater take off on the inlet manifold. My take off connections ( both cast Ally) disintegrated a couple of decades ago and I assembled my own with the help of a local Hydraulic/Pneumatic spares supplier who provided suitable brass fittings that would replace the original items. The Burton item posted earlier is also a good option. These have worked well for many years. This item in your photo is new to me and I wonder if it is some form of thermostat to control water flow; but that is just a guess.
If you have disconnected the heater pipes you should ensure that the flow from the water pump connection to the inlet manifold is maintained, as this is (I believe) important to maintain the coolant flow through the engine.
Hope this helps.. Mike.(1971 4/4 4seat)
When I did some work on my 73 4/3 with cross flow I asked a lot of people about flow through the manifold as I wanted to I stall a valve to control the heat. Every answer I got said it would be fine without the flow.
