TOPIC: '63 40HP Super Seahorse

I picked up a '63 Johnson today and have 2 questions. The electrical box that the battery cables originate from has 3 wires, black, red, and white. Am I correct to assume the red is +, black -, and white starter circuit? Also does anyone know the gearcase ratio?

Finally found a wiring diagram. red is power to switch, white start, and both black wires are grounded together to kill engine when switch is in off position. Where could I find a switch with the 2 m terminals? Still can't find the gearcase ratio so I could figure out prop pitch. Any things about this design I should know about?

I always thought that it was combination of boat and motor combined with the knowledge of WOT RPM compared to designed RPM that determined if you had the right prop. If the motor did not reach designed RPM at WOT, you needed to go down in pitch and vice versa. If the motor was on a very light boat with little drag, the motor might over-rev meaning you need a higher-pitched prop. The gear ratio of the lower unit doesn't know what kind of boat it is mounted on. Have I been doing it wrong all these years?

Phil - you're on the right track. Prop selection is much like choosing the right gear in a car. A motor is happiest when it's in its sweet spot. The old Big Twin style motors like to be in the 4500-5000 RPM range at wide open throttle, so propping them to peak there is best. If the engine doesn't reach that peak, then it is much like going uphill, in 5th gear, while towing a trailer - you want to downshift to get the engine's RPM up to avoid overheating, pinging, preignition, etc. Going down in pitch is like downshifting - engine is free to rev to it's sweet spot. If you're going down the same hill in 2nd gear and the engine is screaming, you want to upshift to get the RPM back down - akin to going up in pitch.

Yes, but instead of buying numerous props, I have a few mathmatical formulas to Figure the hull resistance for top speed at a certain HP. And one to give top speed at a certain rpm and gear ratio. With using both should be able to give a ballpark estimate for pitch to achieve max top speed at given wot rpms. As not to over or under rev. Make sense? Correct me if I'm wrong