A 1957 Evinrude 18 hp weighs 85 pounds, so I would assume the Johnson 18 hp would be about the same, give or take a few pounds.
The fuel mix is 24:1
The 1957 model, 18 hp Johnson outboard, requires an Champion J4C, or NGK B8S, gapped to .030 in.
A Johnson outboard engine, model number RDE19M, would be a 1957 year model, 35 hp outboard.
50 pounds
About 135 lbs. The long shaft weighs 139 lbs.
50 to 1 oil to gas
It is a 1957
JW-13 motors are all made in 1957
Adriel Johnson was born in 1957.
Birgit Johnson was born in 1957.
Arthur Johnson Mellott died in 1957.
Catherine Johnson was born on 1957-10-14.