Does any one know what the best octane, spark plugs and gap for a Johnson 1989/90 88 hp SPL . Thanks, Also, if I am running a 19 pitch AL prop could I swith to a 19 pitch SS. I don't have a tach so I cannot test.
Use FRESH 87 octane fuel with good oil. Champion plugs L77JC4 (non VRO) at .035 gap. If your 19 Al turns the correct RPM then a 19 SS, of the same brand, should be correct. A tach is a good investment. A very good investment. <br /><br />Good luck!
Most of the aftermarket manuals still list plug gap at .040. About 10 years ago OMC changed this spec to .030 for all engines. Hadley is right about the L77-JC4's. The QL77-JC4's would be the resistor version if you are have a engine noise(RF) in you radio. If she's loading up at idle and wanting to stall OMC recomends going to the next hotter heat range which is a L82yc or the Ql82yc if you need the resistor plug.
