What is the fuel for 1957 35hp evinrude outboard motor?

24:1 fuel / oil mix. OMC didn't go to 50:1 until around 1962/63. That outboard was equipped with the 2 line pressure tank system. I would update with a fuel pump that they put on some 1958 and all 1959 models so you can run it off any fuel tank if it hasn't already been done.