Hello all. Have come into posession of a beautiful old outboard which presently runs well. (I'd like to keep it this way, and learn a bit more about it). S/N is 25022-08929.<br /><br />1) Can anyone advise what year this is??<br />(I'm guessing its 1950-57 vintage).<br /><br />2) I'd like to get some advice re fuel mix.<br /> <br />The inside of the motor casing states:<br />"Mix 1 Qt of oil (32 oz) to each Full tank of Regular Gas. For Smaller Qtys, mix on half pint oil (8 oz) per gallon of Gas (SAE 30 Outboard Oil reccomended)".<br />[ This works out to be a 16:1 ratio !! ]<br /><br />I've had other people advise 32:1, and yet others tell me that with today's oils a ratio of<br />50:1 is adequate (and better).<br /><br />Does anyone have a similar vintage Evinrude Big Twin with some experience they are willing to share??<br /><br />3) What is the reccomended plug gap ??<br /> Per the motor casing this advises to use<br /> Champion J-6-J plugs.<br /><br />4) Aside from fogging the cylinders in the fall, is there any general preventative maintainace I should be doing. (Any weblinks or advice is appreciated. )
<br /><br />1) Your 30hp is a 1956 engine, the only year they made a 30hp.<br />2) The correct, manufacturer's recomended fuel/oil ratio is 24:1 using TC-W3 oils (forget SAE 30 weight!) and 87 octane gas. That works out to a quart of oil for 6 gallons of gas. I wouldn't go to 50:1 as there's a couple of plain bearings in your engine that were eliminated before the switch to 50:1. <br />3) Champion J6C replaces the old J6J. This is the correct plug, and the gap should be set to .030".<br />4) Replace the water pump impeller, replace the lower unit fluid, and for goodness' sake, decarb the engine if you think SAE 30w was run through it recently.<br /><br />If you haven't already been there, have a look over at the old OMC site: