Ed Haywood
En-Route
Engine with 40 SMOH raises possibilities. I'm certainly no expert, but am currently installing my own engine (under supervision) after OH. I can think of lots of minor installation mistakes that might rear their head about 40 hours later. Failure to properly tighten a fitting or safety a fastener, improper routing of ignition wires, etc. I spend a lot of time thinking about this as I'm doing my install.