Re: Carb adjustment
You say it runs smoothly. I can't remember if the 1963 is a fixed jet for the high speed. Do you have a high speed adjustment knob?<br /><br />If so, then go out with someone and run at WOT. A little bit at a time, turn the high speed knob slightly toward lean, then wait a few seconds for the change to take effect. At the point where the engine begins to run rough, back the mixture setting off to more rich a little until the engine runs smoothly again. <br /><br />If you don't have a high speed knob, then you have a fixed jet. If the engine's running smoothly at WOT, there's not much to do.<br /><br />As for turning to the proper RPM's that is more likely an issue of setup than anything else. To work with this, you'll need a tachometer. One of the inexpensive tiny tachs will work just fine for this. To determine speeds, a boat speedo is fine, but a GPS unit that can show speed is more accurate.<br /><br />Your engine is rated at 4500 rpm, unlike the more modern engines that are designed to run closer to 6000 rpm. Some may think that yours, too, should run faster. I'm of the opposite school, and think you should be aiming for that 4500 rpm maximum.<br /><br />Prop size is one factor. Trim and motor height is another. As a starting point, try to have the motor's anti-ventilation plate even with the bottom of the boat. If it's a little higher, that's OK, too.<br /><br />From there, experiment with the tilt positions of the outboard. Start with the position that's closest to the transom, then experiment with moving it out one pin at a time, testing each with a WOT run. You're looking for a balance between a good hole shot and maximum speed. If the boat starts porpoising, move the thing back in toward the transom.<br /><br />Once you've peaked out your performance with position and trim, if you're still not hitting that 4500 rpm mark, then you may want to experiment with prop pitch. Lower pitches will raise RPM. Higher will decrease it. That's the general rule.<br /><br />Of course, with that older pin-drive engine, you'll be a little limited in your prop options. Us Big Twin owners are a forgotten breed, pretty much, by prop manufacturers.<br /><br />But, without a tach, all of this is speculation.
