Re: 1954 Johnson Seahorse 10 hp data
That is a model QD-15.
Fuel mix is 24:1 using TC-WX outboard oil per 1964 Johnson Service Manual (covered all Johnson engines up to 1964). The 16:1 was when using 30W motor oil.
Power rating is at 4000rpm, but may run 4500 at WOT. I would run it at 4000.
Spark plugs are Champion J6C gapped at .030", points are set at .020".