the time factor depends on your mechanical mindness/skill, your avaiable tools, a crane or block and tackle?, really comes down to experience and how many times you have taken Asereis (or any motor) out?

my first time on the A12 was intresting always good to have a experinced helping hand to guide you. but since then i have taken the A12 and A14 out a few times (fitted carbies, extractors etc etc) and is everything is quite easy and takes not long at all, after some inital learning