Mercruiser 3.0L conversion to OMC 3.0L

[chevyrockz]

I took a block and head together, from a late 70's early 80's Mercruiser 3.0 that was rebuilt and striped it down. I took all my OMC accessory parts and put them on the mercruiser block and head. The OMC motor is a 93'. What I am wondering is, what differences is there between these two blocks and all the internals.(cam,head,carb cfm,). I put everything together and it runs great but has a lack of power. Ive set the timing and had the holly 2barrel carb rebuilt. (2300 series) The only thing that i can come up with is that all the omc parts that i put on the mercruiser block and head were from a 120hp. and the mercruiser block and head were a 140 hp. I dont know the differences between the 120hp and the 140 hp. Carberation??