OK, GM was [and still is, I believe] building the 2.5 liter and 3.0 liter engine in Mexico simultaneously. MerCruiser used the 2.5 [old 153 cubic inch Chevy II / Nova] block for a 120 hp motor and the modified 3.0 liter [183 cubes] engine with 4" bore as a 130, 135, and 140 hp rated motor. The 3.0 liter crank is different...larger rod journals and the 3.0 liter rods are shorter. Question is: did they cast two different blocks, or just one thick-wall casting that could be bored to either 3_7/8ths or 4 inches? Reason I ask is I have a 2.5 block I'd like to use to replace a cracked 3.0 engine.
BTW, what's with the ratings on the 3.0...did they have to downrate this motor and if it couldn't really put out 140 hp does that mean the 2.5 isn't capable of 120, either?
BTW, what's with the ratings on the 3.0...did they have to downrate this motor and if it couldn't really put out 140 hp does that mean the 2.5 isn't capable of 120, either?