Doing a cambelt on a ford puma but have come across a problem removing the crank pulley bolt. I know when it's all timed up the crank sits against the timing pin so doing the bolt up is not a problem but how do you undo it as when you turn the crank anticlockwise it just turns? I have another longer timing pin in the kit so is this used some how? Guessing I need to lock the crank completely to undo this pulley bolt?
Totally stuck now so if anyone has a clue?

Thanks in advance, Paul M