I always took Cooper to have been a poser. Cooper was very specific when he didn't have to be. If I had to guess, I'd say he data mined a pilot or two a few days before the hijacking for specs and remembered them for the occasion.
There was a guy mentioned in the Geoffrey Gray 302s who pretended to be a screenwriter and was asking the pilots of a California flight how to drop something from an airplane with a beacon in it and retrieve it later. They reported it to the FBI after Norjack.
I can tell you that Chevrolet made V-8 small block engines in 267, 283, 327, 350, 383 and 400 cubic inch varieties, but I couldn't fix one to save my life. I memorized it all to serve a purpose - to sound cool in study hall when surrounded by gearheads and girls with big hair.
Poser. That's my guess.