Studman
Member
I am looking to the all mighty motor guru’s for some thoughts / idea’s
I have pulled the motor before putting her to bed this winter and have started a rebuild
Background – 1993 Sea Ray 290 with 7.4 (454) Bravo 2 outdrive
Did a compression test about midway in the season and got some low numbers, 110 for all but one with 90psi. Never could get the RPMs over 3800 (no, there is nothing wrong with the prop, checked it and changed it). The motor has 850hrs and I was told when I bought the boat that it was repowered about 10 years ago, don’t know the hours.
I was going to just pull the heads and see how that would do but close to the end of the season I started seeing some oil in the bilge, so I pulled it. Good thing too because the front and rear main seals were leaking. I also found a chunk of metal in the oil pan which was one half of the oil pump driveshaft.
Who knows how long that was like that but could have failed at any time.
Took the whole motor apart and dropped off the block (192), crank, heads (156) and pistons (like new) to have cleaned, checked, sized, and put all back together. I will put back the top end and all the acc.
The main question I have is which cam to use? I was told the stock cam is junk and there are a lot better choices out there
I would like to get a little more HP and torque and try to save some fuel, I know it’s a boat with a big motor, but ever bit counts . the pistons are 30 over and will most likely go to 40 over.
My main goal is to get the best fuel economy as possible and have a worry free motor.
Thoughts??
Any help would be great
Thanks
I have pulled the motor before putting her to bed this winter and have started a rebuild
Background – 1993 Sea Ray 290 with 7.4 (454) Bravo 2 outdrive
Did a compression test about midway in the season and got some low numbers, 110 for all but one with 90psi. Never could get the RPMs over 3800 (no, there is nothing wrong with the prop, checked it and changed it). The motor has 850hrs and I was told when I bought the boat that it was repowered about 10 years ago, don’t know the hours.
I was going to just pull the heads and see how that would do but close to the end of the season I started seeing some oil in the bilge, so I pulled it. Good thing too because the front and rear main seals were leaking. I also found a chunk of metal in the oil pan which was one half of the oil pump driveshaft.
Who knows how long that was like that but could have failed at any time.
Took the whole motor apart and dropped off the block (192), crank, heads (156) and pistons (like new) to have cleaned, checked, sized, and put all back together. I will put back the top end and all the acc.
The main question I have is which cam to use? I was told the stock cam is junk and there are a lot better choices out there
I would like to get a little more HP and torque and try to save some fuel, I know it’s a boat with a big motor, but ever bit counts . the pistons are 30 over and will most likely go to 40 over.
My main goal is to get the best fuel economy as possible and have a worry free motor.
Thoughts??
Any help would be great
Thanks
