Re: Prop Swap? 14 x 19 for a 14 x 15 Volvo Penta
You can find very approximate dry weight #'s at
www.nada.com, but they are notoriously inaccurate so of little use. And even if it was close, dry weight means a lot more than gas in the tank. Water in cooling passages, battery, engine oil, outdrive oil, grease, weight of your trailer. Too much to consider, so I wouldn't bother trying to figure out if you think you're close or not on weight. To check for waterlogging, Just drill a few small holes inside your lower transom area and engine mount areas. When wet mulch comes out on the drill bit instead of dry wood, get ready to spend some time on the "Boat restoration and building" forum. If it comes out dry, say a hearty thank-you to the old boat gods and then fill the holes you drilled with epoxy or poly resin, no harm done.<br /><br />Since you're at 3,300, something is wrong, and the problem is not your prop. I'd guess you need to be spinning somewhere between 4,200 and 4,800 rpm, higher in that range is better. Find out the rpm range of your motor. Regardless, if you're at 3,300 with a 14x17, then going to a 14x15 will bring you to about 3,650. Still way too low.<br /><br />Before you do anything, check the tach for accuracy with a tune-up tach or something else to reference with. If it's close then check to see that your throttle plate is opening all the way at WOT, then check compression, test your fuel pump for proper operating pressure and replace the fuel filter, then do a complete tuneup (new plugs, wires, points, set base timing, check timing advance operation, set idle mixture), then check engine/drive alignment, while you're doing that check your gimbal bearing. Somewhere in that process you'll likely find or correct the problem.<br /><br />Don't waste any money on another prop, I'm confident that something here is wrong and needs to be fixed. Aren't used boats fun?
<br /><br />I'd suggest you start posting some questions on the Mercruiser/Volvo repair thread of this forum, you'll get more responses from people who fix these motors and drives for a living. I also highly recommend you purchase a shop manual for this rig to help you through everything.
