MudCreeker
New member
I have an older Merc 9.8 (s/n 7117222), I think it's early 80's vintage. A few years back I stupidly damaged the tiller handle and transom mount. An acquaintance had the bottom half of a 7.5 of the same vintage (s/n 7036508) which appeared absolutely identical, so we just replaced everything from the motor down.
It worked perfectly. Except that I now have a lot less speed.
The prop on the motor now (p/n 48-47670-7) is a 3 blade, 9" diameter, 8 spline, apparently 7" pitch prop. I don't know what the original prop was as I gave the rest of the engine back to my friend and he has disposed of it. But I suspect it was a higher pitch. I've visited the Merc prop selection page, and although it doesn't go back far enough to figure out what prop I should be using, it recommends a 10.5" pitch for a current 9.9 on my boat.
My problem is I can't find any cross reference tables or catalogs that will give me a part number for a replacement prop. Any ideas where I could get such information would be greatly appreciated.
Or if there is any other likely cause for the significant loss of speed, I'm all ears.
It worked perfectly. Except that I now have a lot less speed.
The prop on the motor now (p/n 48-47670-7) is a 3 blade, 9" diameter, 8 spline, apparently 7" pitch prop. I don't know what the original prop was as I gave the rest of the engine back to my friend and he has disposed of it. But I suspect it was a higher pitch. I've visited the Merc prop selection page, and although it doesn't go back far enough to figure out what prop I should be using, it recommends a 10.5" pitch for a current 9.9 on my boat.
My problem is I can't find any cross reference tables or catalogs that will give me a part number for a replacement prop. Any ideas where I could get such information would be greatly appreciated.
Or if there is any other likely cause for the significant loss of speed, I'm all ears.