Need help to identify this engine!

[sylvia_nw]

I just "adopted" a '77 Apollo Bowrider with an OMC engine. Previous owner said its a 3.0 liter, and that it has a cracked head. I need to identify the engine model # so I can try to track down parts. There is a number cast on the block: 2770087 and another stamped on (which I think is the serial #) M04076RB. 980703 is the model number on the stern drive. Where should I be looking? Also~ is there an automotive equivalent to this engine if I cannot find these parts? Thanks for your help!! ~Sylvia :rolleyes:

 

[hystat]

no auto equivalent. If it has a harmonic balancer on the front of the crank it is a 3.0, if just a pulley it is a 2.5L
Those were the two 4 cylinder engines OMC used in that era.

heads rarely crack on these things- have you seen this crack? The blocks sure like to crack.

 

[Master mechanic]

Take off the valve cover... What's stamped on the head ?

pressure test the block...