[TomC750]

Has anyone had to install larger carb jets for their stock 239? My '41 Merc (totally stock) seems to be lean at cruise, all speeds. The carb has been professionally rebuilt and the rebuilder suggested I may have to go larger. The stock jets are #50's. I had a pair of 51's that I tried with a possible slight improvement. Unfortunately, my stock of jets (of which I have well over 200) go from #64 to #99, obviously for higher displacement engines.
Vacuum leaks are nonexistent. As soon as the power valve comes into play it pulls very strong. As I am a bit of a perfectionist, I will be satisfied with nothing other than a perfect running car! Next step I will probably hunt for some #52's.