Hello Ben, It looks like 3/8 BSP both sides. I put the vernier on it to check and it came out at 0.65″ ish and the book for 3/8 BSP is 0.656. My gauge is a smiths unit so it should be the same but check anyway. As for the quarter light rubbers I think they were a one piece L section part that was made to fit the quarter light opening. I will check and look up some old pictures. Window rubbers for our cars are virtually non existent , I am fast approaching needing a complete set but no one does our sizes. I will check on what the quarter light should be, kind regards, Charles
Hello Ben, do you mean the the the thread that is in the cylinder head, next to the hose outlet to the radiator. I do not think it is the block, it is only drain taps fitted down there. 3/8BSP rings a bell but I will have to check
I need to buy a male to male adaptor to fit my smiths water gauge sensor to my 24 stud flathead and believe it’s a BSP thread in the block maybe? Does anyone know what size thread it might be, and also what the thread on the gauge fitting is most likely to be?