Boat - 1990 21' Baja 216 DSR - 4.3LX Mercruiser w/ 1.81 ratio Alpha One
I have this boat for ten years and it came with a 19P Quicksilver S/S Silverado prop. I do not know how the boat ever ran prior to me owning it. Recently, I rebuilt the carb and replaced everything on the ignition system except the Thunderbolt Ignition Module. I also had a brand new outdrive replaced with a 1.81 gear ratio.
At WOT, I am only reaching 3200 Rpms and 32 mph. I have read several other posts with this issue, but could not find any one of them with my same boat. I have taken it to two different mechanic shops. The first adjusted the carb a little and said everything was fine. They replaced the 19P S/S prop with an off brand aluminum 17P. I have better plaing witht the 17P, but still only reaching 3400 Rpm and 32 mph. The second shop completed compression test (150 psi) and checked the timing. They said that everything appears fine with the engine. I was told that the boat is under powered with the 4.3LX engine and that with everything running fine, he feels that the prop needs to be changed. This would require me to drop down to a 13P or 14P. With all the other posts that I have read, I have seen that most people with my same engine and boat size are rocking 19P S/S props and are getting the 4400-4800 RPMs w/ between 40 and 50 mph.
Should I be dropping down to the 13P or 14P prop to get the correct RPMS or is it thought that there is still another issue with the engine that is stopping the RPM from hitting correct range?
I have this boat for ten years and it came with a 19P Quicksilver S/S Silverado prop. I do not know how the boat ever ran prior to me owning it. Recently, I rebuilt the carb and replaced everything on the ignition system except the Thunderbolt Ignition Module. I also had a brand new outdrive replaced with a 1.81 gear ratio.
At WOT, I am only reaching 3200 Rpms and 32 mph. I have read several other posts with this issue, but could not find any one of them with my same boat. I have taken it to two different mechanic shops. The first adjusted the carb a little and said everything was fine. They replaced the 19P S/S prop with an off brand aluminum 17P. I have better plaing witht the 17P, but still only reaching 3400 Rpm and 32 mph. The second shop completed compression test (150 psi) and checked the timing. They said that everything appears fine with the engine. I was told that the boat is under powered with the 4.3LX engine and that with everything running fine, he feels that the prop needs to be changed. This would require me to drop down to a 13P or 14P. With all the other posts that I have read, I have seen that most people with my same engine and boat size are rocking 19P S/S props and are getting the 4400-4800 RPMs w/ between 40 and 50 mph.
Should I be dropping down to the 13P or 14P prop to get the correct RPMS or is it thought that there is still another issue with the engine that is stopping the RPM from hitting correct range?
