Maybe you can tell us your speed, correlating RPM and what the max rated RPM is as well as the current prop you are using...
I did basically the same thing you are doing, minus the crank modification. My motor went from 260 HP to a whopping 280 HP yielding me a massive...
I have a volvo 280 that has been a nightmare to work on...you need special tools to do a lot of things correctly, and they seem to leak a lot!
I had a simlar problem with my boat. I now have a new engine!
Once you are certain that the tach is correct, you might want to consider running a pro with lower pitch. I aould guess that a 14x15 or 14x14...
Hi everyone...this is my 1st post here. I just bought a 1988 24' Marathon cruiser. I beleive it has the Volvo Penta 280 or 290 stern drive. I...