Re: 1990 sp0rt 192
I have a 1990 192 Sport as well - WITH the VP AQ171C.
Yes, a "four banger" but the most powerful one Volvo ever made (DOHC head with 167hp). Gets on plane with 7-8 people on board.
Cheap on fuel, but if you get any indication of "dieseling" when shutting off, run higher octane fuel and the correct spark plugs (I run NGK BPR6HS).
All that said, the parts for the AQ171 are (can be) VERY expensive since this was a short-run motor until Volvo went 100% to GM blocks. The exhaust manifold runs closer to $2,000, so it is warranted to care for it ahead of time.
Make sure you flush every time. Keep an eye on timing belt since the DOHC is an "interference" engine (broken timing belt = bent valves or worse). Make sure engine gets proper cooling and "care" for your tank and heat exhanger by replacing glycol now and then (yes, aluminum do corrode).
Keep an eye on the impeller and strainer.
If questions, just ask
Edit:
Jeff,
After reading more posts here tonight, I see you are "deep in" a restoration project, and likely have picked up more info than you need/can handle. In case you want information on the AQ171C, or to part with some items, let me know what you have.