Re: twin 4cly good or bad
The 488 is a 470 with a Quadrajet 4bbl carb.
Do you know what a 470 is? It is not an automotive engine.
Aluminum block, designed by Mercruiser using an open deck design (strike 1) using a Ford 460 head.
Charging system was a rotor/stator type affair with a water cooled regulator (strike 2).
Most replace with an alternator kit, also expensive.
Overheats typically cause a need for a head gasket due to the open deck design,
Cam runs the engine circulation pump, so when the cam seal leaks, you get antifreeze in the crankcase with the oil Not Good. (strike 3)
Merc stopped using them in 1989 (23 years ago) and some major parts are NLA and getting hard to find except used (strike 4)
Other than that, a good running one has good torque, and fuel economy with a 2bbl. The Qjet, not so much if you open the secondaries.