Identify engine
jeffro, some pictures of the engine will help. Something does not compute. Do this for me. Drivers side. there is a crankcase ventilation intake. About 4 in x 2 in. Is it at the front of the engine or the back.
The number you gave does indicate a series 40 which is a 248. Prewar serial numbers started with series number, in your case a four. Postwar, I believe, this was changed to the last number. I was under the impression all 320 engine numbers were behind the distributor while 248 numbers were in front. Pictures of that number and the location of the vent intake will help.
Ben