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I have always warmed up an SU-carb-based car (and, frankly, had to so-as to get the car running nice), but with fuel injection:
http://bestride.com/research/tips-and-tricks/is-it-safe-to-warm-up-your-cars-engine-when-its-cold
http://bestride.com/research/tips-and-tricks/is-it-safe-to-warm-up-your-cars-engine-when-its-cold