rebuild or replace

[joseraposo_46]

Hi all. I was hoping for some advise. I have a seized motor that has been soaking in mystery oil for 3 weeks. I was told these motors ran rough a year ago. The starboard motor does spin freely so I have not spent much time on that but the port motor is locked up solid. Is it worth rebuilding these motors on repowering with newer fuel injected motors or switching to diesel. Thank you.

[lobsta1]

I'm assuming you are talking about a 454 BB. With what you have stated, I would be looking for another block with heads to replace yours. Diesel would be prohibitively expensive. Just remember that the STB motor is counter rotating.
Good luck
Al

[joseraposo_46]

Thank you for the response. I have found a used pair of 454BB with low hours and fuel injection that were in good running order when removed. They also come with transmissions. How can I tell if the transmission will match my existing prop setup.

[dougl33]

The other questions are:

What year is your boat?
Why did the engine seize?
What material is your fuel tank made of?

What I'm getting at here is did your engine fail because of ethanol and a dissolving fuel tank? You don't want to replace any engines until you rule out the fuel tank.

[lobsta1]

Hi Jose, listen to Doug. I believe your current trannys are 1.88:1 As I mentioned the existing STB engine is counter rotating. If the new blocks have fuel injection then they MAY both be standard rotation with the reversal done by the tranny.
If the replacement transmissions are Borg Warner, there should be an identifying plate on them. If ZF, I have no idea.
It really helps if you give all known info when asking a question.
Al

[joseraposo_46]

I apologize for not giving more information. I purchased the boat 2months ago with very little history. The boat is a 1980. I do need to replace the fuel tank because its fiberglass. The fuel lines had been disconnected and the motors both ran on temporary fuel cans a year ago. Since my last post I was able to free up the port motor. The starboard motor was already free. This weekend I will do compression testing of both motors. Thank you all for your information and advice.