OK so… I now have a solution for this hole (plug it and fit a temp sender in the radiator hose) but I’ve found a new hole, in the inlet manifold.
As you can see from the picture, there’s a hole, and there’s a similar one the other side which has a little grub screw in it. There does appear to be a thread on the hole, but I’m wondering whether it should have something in it? There’s also a hole the other side.
Thanks for the response, that’s what I wondered but there’s a similar hole the other side, actually two. Seems a bit odd to have so many? There’s only one grub screw (the one you can see in the picture), all the others are empty.
Ben. Many 1950’s vehicles had vacuum operated windscreen wiper motors. Our 1954 Ford Consul did. Certainly some of the Ford V8 distributors had vacuum advance /retard mechanism. My P1 amonst them. Therefore I wonder if that is the reason for your intake manifold holes. If the engine was ex a commercial vehicle it may have had vacuum assisted brakes