There was a post recently asking about the color of a Merlin. These photos are from the P-51B/C maintenance manual, and while it is black and white if you compare the darkness of the data plate on the crankcase to the rest of the engine, it looks like it is a medium grey. This is of course a Packard Merlin, similar to a Merlin 61 in an Spitfire Mk IX, with the two stage supercharger and large intercooler box.
It’s dangerous, trying to interpret black and white photos. Rolls-Royce reckon that satin black was the designated colour, except for marine engines, which were finished in cream. In those photos, the printer would only need to use a less contrasty paper, and the black turns to grey, with the plate, being flat matt, absorbing more light. Also, the areas, which are not reflecting the light straight back, towards the camera, e.g. the sump and rocker covers, are obviously black.
Edgar
Thanks for the color info, Edgar.