This x2 sounds like it jumped a tooth. From my experience they tend to jump upon shut down. I believe 318 is an interference engine so if it jumps a few teeth valves will clash. Also I don't believe 340 uses the same balance on the converters if it was a cast crank. Pull your plugs, pull distributor cap, socket and breaker bar on the crank nut , turn it over forward and pull it back and observe rotor. It will tell you if you have excessive slack in the chain. Don't keep starting it and shutting it off. The lack of vacuum also indicates this.
