When I was sixteen I decided to take auto prac and theory as something I would find non academically useful. Most of the guys in the class had been doing it for a couple of years and were fairly advanced. The teacher handed the three noobs an old Ford Consul engine and told us to dismantle and reassemble it on an engine stand until it ran well. The two other guys on the project dropped out of the class not long after disassembly, I fiddled around for weeks washing parts and rereading the manual until the time came that I had a pile of parts and two weeks until I had to turn the key. The teacher let me have a few hours every afternoon to work on it as well as regular classes, I was still tensioning the head studs on the last day, I was static tuning minutes before I had to start the thing. Thankfully it started pretty much first pop.