One of the previous owners put the dumb 132AC (1592cc) engine in, which when the timing belt came loose on the previous owner, snapped both valve heads off on the #4 cylinder. I bought a "new" 20 year old 125BC (1608cc) engine to replace the non-original, piece-o-crap 132AC.
The valve cover and cylinder head gaskets leak (not too bad considering age), and the transmission (5-speed) needs new seals.
I replaced all of the gaskets and seals on the engine and transmission, rebuilt the carburetor, and made everything nice and shiny. It all works great now!
The only other major problem left to take care of is body cancer. There is a 3 inch wide hole to the left of the driver's seat, a hole (puncture maybe, not rust) in the floorboard, and the suspension to body connecting points are rusted (HAZARD!).
This car is seriously fun to drive!
When I rebuild the engine (how many thousands of miles later?), I plan on making it a 14:1 C/R, hot cam, 500cfm, tunnel ram, race car. Theoretically, that should make around 230HP and 210ft.lb.
With a Rotrex supercharger, that Fiat engine (125BC) would make 250HP on a street setup and pump gas on 1.6L!!!