Hi all...hopefully you'll excuse me if I'm in the wrong place here..I recently found a great deal on an 89 searay 250da cruiser with a brand new mercruiser 5.7 litre 2006 repower...previous owner passed before testing the repower...I bought from his wife who knew very little boat anything..I went to pick-up and was unable to test on water,so all I had was a hose test/physical look-over...engine had less than 1hr run time and was excellent in it's running...outdrive shifted great in forward and rev...no leaks or noise...smooth as silk...I tow it home,excited as heck about my new boat...I'm a retired Mechanic with a few years in outboards to my credit, and was confident in my purchase being a good one from the preliminary checks before purchase..finally get to the water and things were great until I got it partially planed and got the over rev limiters excited
..Around 5000rpm..I pulled the throttle back to around 3500 and realized something was wrong...my Mercruiser knowledge was vague and slim at best...after some playing around,I checked the prop pitch and applied my outboard knowledge on pitch and assumed that the prop was wrong and had been swapped maybe..I installed a Solas 4 blade 19 pitch and retured to the water...wow what a difference...the boat planed well and was smooth as can be compared to the previous run,but the rpm's were still a bit high according to the engine specs..about 550 or so too high at wot..so I ordered a 21 thinking it would be most perfect...while waiting on the prop to arrive a little research reveals that the outdrive has been changed with the wrong ratio...1.84 from a v6...the 21 put the rpms in check,and the boat runs out in the low to middle 30's,depending on trim...all sounds great with this set-up...my question is this..I know it needs 1.47 or 1.50 ratio according to specs found,but it performs great with this set-up for my preferences...will it harm anything or should I replace the upper and reprop it according to specs...educate me please..Thanks in advance...
..Around 5000rpm..I pulled the throttle back to around 3500 and realized something was wrong...my Mercruiser knowledge was vague and slim at best...after some playing around,I checked the prop pitch and applied my outboard knowledge on pitch and assumed that the prop was wrong and had been swapped maybe..I installed a Solas 4 blade 19 pitch and retured to the water...wow what a difference...the boat planed well and was smooth as can be compared to the previous run,but the rpm's were still a bit high according to the engine specs..about 550 or so too high at wot..so I ordered a 21 thinking it would be most perfect...while waiting on the prop to arrive a little research reveals that the outdrive has been changed with the wrong ratio...1.84 from a v6...the 21 put the rpms in check,and the boat runs out in the low to middle 30's,depending on trim...all sounds great with this set-up...my question is this..I know it needs 1.47 or 1.50 ratio according to specs found,but it performs great with this set-up for my preferences...will it harm anything or should I replace the upper and reprop it according to specs...educate me please..Thanks in advance...
