Re: 1957 Evinrude 18HP will not start Home › Forum › Ask A Member › 1957 Evinrude 18HP will not start › Re: 1957 Evinrude 18HP will not start stanleyUS Member - 2 YearsReplies: 613Topics: 114 August 13, 2018 at 8:15 pm #81093 Spark needs to jump a minimum of 1/4",plug wire end to block.3/8 to 1/2" is even better.