I had a white (aftermarket) convertible Ford EXP in college... twice, someone tried to cut the roof and steal it. Twice, they couldn't get it started because you had to give it exactly 2.5 pumps of the gas pedal to prime the carb. Without that, it would NEVER start. With that, it would start every turn of the key.
First time I caught them and they ran away... second time I was smarter, called the cops from my window, and the cops chased the kid down the street and cornered him. Almost shot him when he reached into his jacket... and all that was in there was a beer.
There is no better antitheft device than an old carburetor.