New to me boat motor questions

[Bondo]

Re: mercruiser 3.0 with 90 psi compression on all cyl.,

Ayuh,... Welcome Aboard,... If that's the best numbers it can pull,...

It's a rebuildable core, rather than a runnin' motor..

 

[flipbro]

90 is low. But it's consistent that's good. It's a rebuild able block..

 

[Rick Stephens]

Agree with previous posters. Mercruiser minimum compression is 100. Needs a rebuild.