I have a '86 Caddy RWD with the 4.1L. It runs really good, but when it goes out(as these engines are known to do), can it be replaced with the 307 Olds or Chevy 305/350?
You’ll have to probably do some motor mount and exhaust alterations along with modifying things related to emissions (hoses, ECM, etc.) IF you live in a emissions testing state and want to retain that stuff.With no emissions testing required the best thing would be to clean all of that garbage off the top of the engine and drop an Edelbrock Performer carburetor on it or use an early Quadrajet.
I think you can use the Olds engine but cannot use the Chevy. The bellhousing bolt pattern on the Cadillac transmission are the same as the Buick/Olds/Pontiac, or BOP as it’s called. The Chevy is pattern is different and while the 350 Chevy would be the best engine you would also need the Chevy transmission.