Depends on the type and make of engine, your expertise and the tools available. I could totally dismantle and rebuild a lawnmower engine in a day, - a Chevy 350 took me a little longer.
Bout 2 minutes
There is not enough room here to try to take you through all the steps to tear down an engine, determine what all needs to be done in a rebuild and then take the required steps to do a credible rebuild. I would suggest you get a repair manual, Chilton or Haynes. There you will find the process broken down to individual processes that will result in a decent rebuild. Good luck.
Take it to jasper they rebuild any motor.
it will probably take centuries
they need money to rebuild and i do not konw
about 2 years
3years?
it took about a year and a half
To put the camshaft in takes a few minute. To strip down the engine to the stage where you can fit the camshaft and then rebuild it can take several hours.
about 13 years
Depends on how well you take care of it I have seen them go up to over 300000 miles. But to put an average to it on a normal(non-M car) BMW engine 200000. with no major engine issues.